Riding lawn mower gearbox. Fix Your Hydrostatic Transmission Problems Fast

Fix Your Hydrostatic Transmission Problems Fast

Combustion engines, like those found in most cars, transfer power to the vehicle’s axle, which turns the wheels. Hydrostatic transmissions found in most modern tractors and zero-turn mowers, work by transferring power from the engine to hydraulic pumps which use liquid pressure to move the wheels. There’s no need for gears, and changing speed is smooth and efficient.

With any transmission, things can go wrong. The first step is to read your Operator’s Manual. There are many different types of equipment with hydrostatic transmissions, and we can only offer general advice. Your tractor operator’s manual will have information specific to your make and model, and will offer helpful information about where to find filters and other parts that might require servicing are located on your tractor or lawn equipment.

Where to find more information:

Hydrostatic transmissions include mechanical parts such as a differential and a drive axle, plus rubber or metal hoses the liquid is pushed through. Failure of any mechanical component, a broken hose, or clogged filter will cause tractor hydrostatic transmission problems. But the most common issue will be the oil itself.

In the transmission section of your operator’s manual, you’ll find a section that covers oil viscosity. Here’s an example from a John Deere manual. Note that, while temperature affects viscosity, the right oil has enough range to operate in any reasonable weather.

Here are some basic troubleshooting tips to fix your hydrostatic transmission lawn tractor problem fast!

Zero-Turn Mowers: Purge Your Hydraulic Drive System

Zero turn hydrostatic transmission problems can start with air in the system, a condition known as cavitation. When the pump is full of air instead of oil, it can’t generate the pressure needed to provide power. This is pretty common in zero-turn mower transmissions. After your mower has been stored for the winter, it’s a good idea to purge the transmission before use. It’s also a good first step if your motor is sluggish or slow.

NOTE: If your mower or tractor has a transmission that must be removed for service, be sure to purge after it is serviced and before you use it.

Park the mower on level ground, set the parking brake, and put the rear on jackstands.
Make sure the oil reservoir is properly filled according to specs.
Disengage the transmission (check your operators manual to see how this is done).
Sit in the operators seat and start the engine.
With the engine running, move throttle control to slow position. Position the motion control levers in neutral (N) and disengage clutch/brake pedal.
Push motion control levers forward all the way and hold for five seconds.
Pull motion control levers to full reverse position and hold for five seconds.
Repeat steps 6 and 7 three times. This purges any air from the hydraulic transmission system.
Put the control levers in neutral (N). Shut the engine off and set the parking brake.
Check the oil and top off if necessary.
Engage transmission.
Remove from jackstands, start the engine, and disengage the brake.
Move control levers forward and roll about 5 feet. Then slowly reverse about the same distance. Return the levers to neutral and repeat this steps three times.

You’re done! The air is purged from your system and your zero-turn mower is ready for action.

Check The System

If your system is purged and you still have a problem, it’s time to do a little basic troubleshooting. Start with a complete visual check of the hydraulic system.

Check the oil level and add oil if needed.
Inspect the hoses and connections for damage or signs of leaks.
Clean pump cooling fins with a rag, brush, or compressed air, and check for damage.

Change Your Hydraulic and Steering Fluids

Sluggish operation is often due to old or overused fluids. If there are no signs of fluid leaks or damage, it may be time to change your hydraulic and steering fluids.

Hire An Expert Troubleshooter

If you need help troubleshooting your tractor’s hydraulic system, call your dealer. Their service department should be able to ask the right questions, give suggestions, and you can make an appointment for service if necessary.

Blairsville, GA: 706-745-2148

Some things are beyond DIY. When it’s time to call in an expert, don’t hesitate. Your tractor represents a significant investment in terms of both money and delay. It’s one of those farm equipment essentials you simply can’t do without. When it needs to be fixed fast and done right, call an expert!

Image source: Z915E ZTrak Zero-Turn mower with hydrostatic drive train, deere.com

Fix Your Hydrostatic Transmission Problems Fast

Where to find more information:

Cub Cadet XT2. Weak Reverse Quick Fix

Here are some basic troubleshooting tips to fix your hydrostatic transmission lawn tractor problem fast!

Zero-Turn Mowers: Purge Your Hydraulic Drive System

NOTE: If your mower or tractor has a transmission that must be removed for service, be sure to purge after it is serviced and before you use it.

Park the mower on level ground, set the parking brake, and put the rear on jackstands.
Make sure the oil reservoir is properly filled according to specs.
Disengage the transmission (check your operators manual to see how this is done).
Sit in the operators seat and start the engine.
With the engine running, move throttle control to slow position. Position the motion control levers in neutral (N) and disengage clutch/brake pedal.
Push motion control levers forward all the way and hold for five seconds.
Pull motion control levers to full reverse position and hold for five seconds.
Repeat steps 6 and 7 three times. This purges any air from the hydraulic transmission system.
Put the control levers in neutral (N). Shut the engine off and set the parking brake.
Check the oil and top off if necessary.
Engage transmission.
Remove from jackstands, start the engine, and disengage the brake.
Move control levers forward and roll about 5 feet. Then slowly reverse about the same distance. Return the levers to neutral and repeat this steps three times.

You’re done! The air is purged from your system and your zero-turn mower is ready for action.

Check The System

If your system is purged and you still have a problem, it’s time to do a little basic troubleshooting. Start with a complete visual check of the hydraulic system.

Check the oil level and add oil if needed.
Inspect the hoses and connections for damage or signs of leaks.
Clean pump cooling fins with a rag, brush, or compressed air, and check for damage.

Change Your Hydraulic and Steering Fluids

Sluggish operation is often due to old or overused fluids. If there are no signs of fluid leaks or damage, it may be time to change your hydraulic and steering fluids.

Hire An Expert Troubleshooter

If you need help troubleshooting your tractor’s hydraulic system, call your dealer. Their service department should be able to ask the right questions, give suggestions, and you can make an appointment for service if necessary.

Blairsville, GA: 706-745-2148

Image source: Z915E ZTrak Zero-Turn mower with hydrostatic drive train, deere.com

How To Know when your Riding Lawn Mower is past repairing

If you own a home with a relatively large lawn then using a push mower is something that takes a lot of time and energy. You have two choices either you buy a Riding Lawn Mower or you pay someone to cut your grass. The cost of a lawn tractor is probably one of the largest expenses as far as tools for the home and when they break down the cost of repairing them can be very expensive.

Since you probably don’t have a romantic attachment to your lawn tractor you have to be realistic about the cost to service them. Some repairs are general maintenance that must be performed to keep your riding mower in good condition. If you don’t perform maintenance on a regular schedule you will end up paying many times that in repairs for things that never should have gone bad.

Eventually though your lawn tractor will need replacing. This how to will help you figure out when its a good idea to replace your riding mower rather than dump time and money into it trying to repair it.

How much do new Riding Mowers cost?

It depends on the type and make of the riding mower you are considering purchasing but at the very minimum you can expect to pay from 750 to 1,400 for a new general purpose riding mower.

The lower end riding mowers will be very basic with fewer options for upgrading. They normally won’t have extras like headlights for 3am lawn cutting or attachments like snow plow blades but they will get the job done for most yards.

Higher end models will have larger engines in the 20hp range which can be used for a variety of different tasks like towing a lawn cart or even a small boat in your yard. They will also have all the options including a beer holder.

What repairs are just too expensive to justify?

The most costly repair for any gasoline powered device whether its a lawn tractor or a chainsaw is the actual engine. There may be parts of an engine that you can repair or replace such as the carburetor, starter or maybe even the head and valves but when it comes to total engine replacement you are normally looking at half the cost of a new lawn tractor.

For instance a Briggs and Stratton 15hp engine will run you about 400 and a 20hp v-twin can set you back somewhere in the area of 800 and if you are thinking about buying a used engine don’t even think about it because any repair center will charge you at least 75% of new and one you might buy from a listing online you will have no idea how long it will last. You can try replacing your engine and it is a relatively easy repair to drop in a whole new or used engine but the cost is very high.

Transmissions are the next highest repair for riding lawn mowers. If you have a hydrostatic transmission built in the past 15 years you can expect to pay somewhere in the area of 200 for a new transmission. The problem is unlike engine designs that are very similar throughout the years you may find that your model transmission is no longer supported. Parts may not be available or they will be very expensive and hard to find new. Used parts will be hit and miss because there will be a lot of people in your position willing to bid up beyond their reasonable range.

Individual parts for transmissions are normally not available as the manufacturer normally recommends full replacement.

What repairs are worth attempting before I buy a new Lawn Mower?

Other parts that can be expensive but completed within a reasonable cost include:

45 Battery 50-75 Seat 45 Engine Starter 25 Voltage Regulator 40 Coils 100 Cutting Deck Rebuild Kits with blades and spindles

Tires and wheels are expensive and many people decide to use inner-tubes when they have a tire that will no longer hold air but still has decent tread on it.

Suspension parts are normally not really expensive but if they require replacement it normally means the whole tractor is worn from many years of use. If they are damaged from abuse or impact then you may need additional parts that you don’t first notice.

General tuneups are not considered things that are out of the ordinary.

You can expect to pay 50 to 75 a year on your Riding Mower to keep it in good working order including your tuneup parts that will cost about half that.

Final Note

Whether you are trying to save your lawn tractor or considering buying a used one that you can fix up the costs of repairs and time to perform them must be considered. If you are hiring out the work then labor must also be accounted for and you can normally double the price of the part to find your total. That means if a deck rebuild kit costs 100 and you bring it in for service you are going to walk out with a 200 bill at the minimum.

Some repairs are very easy to do and some are expensive the problem is understanding what you are getting yourself into.

If you were considering buying a used riding lawn mower that had a bad engine then you should almost get it for free because of the cost of new engines.

If the price of the used riding lawn mower and the repairs to get it in 100% functioning order are more than 50% of the cost of a new riding mower then walk away from it.

If you are repairing your own mower then you only have to account for parts and maybe labor or the worth of your time and the problem waiting a couple weeks for parts to get to you if they must be shipped.

If you can complete the repairs and have a mower that works like new but may have some scratches and wear then go for it. But be careful about sinking money into something just to save it. Sometimes buying new and selling the old one for parts is the best way to go. There are always people willing to buy your lawn tractor that need many parts other than an engine or transmission and it is worth 100 to them which you can put towards a new one.

Introduction: How to Make a Racing Lawn Mower (Updated!)

Notice: I’ve recently completely turned this mower into a new build. If you’ve read this before, proceed to step 12 for the latest updates. Otherwise, start reading below for the original build.Thanks to everyone who has commented before. As always, feel free to ask questions and I’ll do my best to answer.Click Here to proceed to step 12.

In this demo, you’ll get some ideas of how you can make a real racing riding mower used in national events. Have fun turning what used to be the family lawn mower into a fire-breathing high speed racing machine. Also- I’m constantly making changes and modifications to the final machine so check back to see what I’ve done. The next plans I have include steering upgrades.

Please read the following paragraph before proceeding.

Before we start, there’s a bit of safety to discuss.Yes, racing lawn mowers from an outward perspective is sort of funny ( which it is!)But its important to realize that racing mowers such as these are heavily modified to handle much greater speeds than the original mower was designed for. Many of these mowers go 50MPH or more.Making a race mower isn’t as simple as taking a stock tractor and making it go fast without any alterations. So its important that the frame, brakes, steering, engine, and wheels are modified or altered to handle this additional speed.So to make this point doubly clear, it is NOT a good idea to take a bone stock mower and make it go fast. You can, and will get hurt if you do so, and trust me- I’ve seen enough people wreck due to this very reason. So play it safe. Secondly, if you do plan on racing, make sure and check out the rules for your chapter and wear appropriate safety gear such as a helmet ( motorbike), gloves, boots, and long pants.My mower is built using ARMA ( American Racing Mower Association) rules and regulations. Lastly, your mower must have an approved jet ski/snowmobile style safety tether switch. If you fall off ( which we often do) the mower must automatically shut down or it’ll keep right on going! Racing mowers might seem silly, which it sort of is, but you can get hurt if you’re not careful. So be safe!

Ready, let’s get started! The ‘victim’ I chose for this build is a late 60’s Grants mower. Tiny little mowers like these were produced back when riding mowers were still deemed a luxury. They’re little more than a seat sitting on top of a mower deck. Most used smaller engines. The advantage of using such a little mower is that you can reduce the weight dramatically by simply having a ‘legit’ riding mower complimented with a larger engine, hence a higher power/weight ratio. Don’t get attached to it. When its done, there won’t be much left of the original.

The first step is to strip the mower down to the frame. Modern mowers usually have a single stamped piece of steel. Older mowers like this one have frames made of square tubing or slabs of steel. This will give you an idea of how much of the mower is actually usable and how you can lay out the drive, steering, and brake components. Besides the hood, what’s leftover to use isn’t much. The rest are worthless such as the stock wheels, steering wheel, and transmission.

Step 1: Configuring the Build.

The next step is probably one of the more difficult parts of the build: configuration and finding parts. Building one of these is sort of like building a small car with all its various systems. Since all of these racing mowers are one-off type builds, finding the parts that will work can be a pain. I’ve had a lot of questions about where the tires, clutch, and right angle gear box ( transmission) comes from. the gear box can be found on ebay. The tires are go cart tires and can be found online on any site that sells go cart parts. The same is true for the brakes and rear axle components. The front axle is a custom unit built by a company called Acme Mowersports.

A list of parts needed for this build are:

A: Engine B: Transmission ( right angle gearbox) C: Centrifugal clutch D: sprockets E: Front axle and spindles F: Rear axle and axle hangers G: steering wheel H: Brake system I: chain J: electrical components K: Wheels, tires, and hubs M: Gas lever N: high endurance engine components

Many of the others need to be made by hand. One thing that’s helpful is that many of these components such as the rear axle and hangers,wheels, hubs, spindles, and brakes are basically go-cart components. Some golf cart and motorbike components work as well. Sprockets and such can be had from sites such as Mcmaster.carr.

Once you get all the parts, the build actually goes pretty quickly.

Step 2: Frame Reinforcement

The next step is to beef up the frame or make alterations that will work with your components.Its important to realize that these mowers will be racing on what tends to be really rough dirt track. They have no suspension, thus the frame takes a severe beating. Reinforcement is critical to avoid having the frame flex and ultimately crack from fatigue. The rear of the frame was cut about 6 from the rear. Throughout the build, I used 1×1 square tubing which is easy to weld and work with. This is what I used to create the square frames in which the mounting brackets were welded into to hold the rear axle bearings. I chose to use a 1/1/4 rear axle because that size is highly common and thus easier to get parts like wheels and sprockets for.

These square frames were welded into the frame, then the end I cut off was welded to the back. The minimum height requirements for my class is 4 from the frame to the ground. So its important to know what size wheels you plan to use and where to mount the axles in order to meet that requirement. The lower you can go, the better handling the mower will be. Mine site just at 4 off the ground.

Next, I welded two lengths of square tubing along the top of the axle brackets to the front tubular frame. I did this because the transmission will go underneath. A piece of diamond plate will cover it, and above will be the seat. This will give me easy access to servicing the chain and transmission and also protect me from flying debris or potential chain failures.

I am using a right angle gearbox for this build. Why? Because the other choice is to use a 3-5 speed gearbox used as standard equipment on mowers. These work fine, but it also means you’ll have to change the grease in them and perhaps invest in hardened gears since the originals will strip out much easier. With a right angle gear box, or RAGB, there’s only two moving parts. Plus, they are made for higher speed applications and therefor perfectly suited for this application. simplicity means more reliability.

Additionally, I am using a centrifugal clutch. This is a higher quality, higher HP rated unit that is heavier duty than typical go-cart clutches. The springs can be adjusted for higher or lower engagement.

Step 3: Steering System

The next step is one of the most important of the build. Many people go out on the track with the stock steering setup. That’s a big mistake for a number of reasons. For one, the stock components aren’t made for going 50MPH, as is none of the other stock components. Secondly, there’s more to steering besides making the wheels turn. You also need to have the proper caster, pitch, and turning radius so that the chassis will handle corners better.

Most mowers come with a gear driven steering setup. These are worthless and tend to pop out of place. So you’ll need to make a direct steering system. In other words, a solid connection between the steering wheel and the front wheels.

For this build, I bought a pre-built front axle from a guy in Texas. He has a small business called Acme mowersports and can be found at www.acmemowersports.com. His front axles are a good deal because even if you were to build your own, the cost would be only slightly less. With the Acme axle, the proper caster and degree of inclination are already built-in, which will save you lots of time. These come with the radius arms as well as connections for the steering axle, which on mine runs down the center of the front of the mower over the top of the engine.

Next up is the installation of the steering shaft running along the front of the frame. This mower has an unusual setup where the steering linkage runs over the top of the engine. An a arm runs from the steering wheel pitman arm to a shaft running down the front of the frame to the radius arms of the front axle spindles. First, I got some 1/1/4 steel pipe and cut some lengths about 2 long. On each end, I placed a bearing in which the steering shaft fits through.

The top of the front steering shaft has a removable lever to attach the piece of linkage coming from the steering wheel. This enables you to remove it if needed. If you look at the pic entitled pitman arm detail, this is the steering wheel shaft with the pitman arm welded on. As you can see, the arm on the end is rounded and has three holes. There’s a reason for this, which is to prevent the heim joints, which are the screw-on ball bearing pieces on the ends of the rods from binding. The reason for the three holes is to give you adjustments to the steering sensitivity. Further out gives you more slack. Further in tighter. It is also important that the arm running across the top of the engine area has threads on either end. This way the heim joints can be screwed in or out to adjust the amount of right and left turn in the wheels.

In The pic entitled: Steering arm, you can see how this system works together. Lastly, the turn right pic shows the underside linkage and radius arms. If you see the t shaped piece, that’s where the radius arms connect. The T is welded to the bottom of the front steering shaft.

Another step is to determine the angle of the wheels. Generally, it is better to have the left wheel turn in more than the right. I usually have the left wheel turn in @ 10:00 and the right at 2:00.

Lastly, you will need to install what are known as stops, which are basically welded on rods or bolts to prevent the wheels from turning too far. If they turn too far, the steering wheel will turn completely over, thus reversing your steering! Not good! For this build. all I did was weld two 5/16 pieces of steel rod to the front of the axle, right where the spindles swing in and out. The spindle arms simply hit the stops. I held the wheels in place at the correct position and placed the stops at exactly where the spindle arms hit, then welded them into place.

Once you have the steering done, then you’ve just completed one of the hardest steps!

Step 4: Installing the Transmission Or- the RAGB

The next step is to install the RAGB ( transmission). This was a tedious task because the RAGB I chose has an unusual triangular shape and a strange bracket. Additionally, the RAGB shaft has to be far enough off the ground, yet not too far up as to protrude above the diamond plate covering it. When all the measurements were done. I had 1/4 between the top of the RAGB and the cover. The RAGB sits on two cross members welded in the frame. If you look at the pic called: Battery bracket, you can see how it is configured. In the next pic you can see the RAGB bolted into place.

Before we get any further, you’ll need to determine what your gearing ratio will be. The RAGB is a 2:1 ratio, meaning that two turns go in, one comes out of the output shaft. I suck at math, but my gear setup is as follows: Centrifugal clutch is 14 tooth. Input on RAGB is a 14 tooth. Output on the RAGB is 12 tooth, and the rear axle sprocket is a 40 tooth. That worked out well, but I have no clue what the final ratio is. The engine speed is around 4,500-5,000 RPM.

I’m using an all chain drive system. Many use belts, but I like the idea of using a chain. I used #35 chain for this build, but many use #40.

The next step is to install chain tensioners. The chain needs to be somewhat taut, but not tight. All chains will loosen and ‘stretch’ with use. So you need to have tensioners to keep that tension at the right level. The RAGB to rear axle tensioner was a problem because there was very little space to install one. My solution was to install a skateboard wheel that slides up and down in a 1×1 piece of steel with a slot milled along it’s length. This enables you to slide the skateboard wheel up and down against the chain. You wouldn’t think skateboard wheels would hold up, but they work great. Seeing as how they are designed to handle a person riding on asphalt, chain doesn’t cause any damage to them at all. In this setup, I just have enough room to get into the area with a wrench to loosen/tighten the tensioner.

Step 5: The Brake System

Next up is brakes. There are several types of brakes you can use: mechanical or hydraulic. The later is generally better and easier to install because you can route the brake lines to wherever you want them. The brake system I have is an MCP go cart brake kit. They run around 150 including the master cylinder, rotor, rotor hub, caliper, and brake line. You can also use motorbike brakes if you have any laying around.

First, I drilled two holes through the frame where the bolts holding the caliper would go through. Many people create a caliper mounting bracket. Mine just happened to conveniently work without it. After that, I bolted on the caliper and made sure it aligned properly with the rotor. The rotor and other components on the axle are adjustable and slide back and forth on a keyway milled into the axle shaft. Once adjusted, you lock them down with set screws.

Next, I installed the master cylinder. This is bolted through the frame. The aluminum piece with the three holes is the connection for the brake pedal connecting rod, which is made out of 1/4 steel rod bent @ 90 degrees. The other end of the rod connects to the pedal. I welded a nut to the end of the rod and drilled out the threads. Make sure you do a real hot, molten weld here because you don’t want that to fail. The pedal is made out of scrap steel and a short length of 1×1 square tubing with a hole drilled through the bottom in which to run a bolt through the frame. A nylock nut on the other side allows it to stay in place yet swivel back and forth.

Once you’ve gotten everything to work smoothly, you’ll have to bleed to brakes. But hold off on that until closer to the end.

Step 6: Installing the Floor Plates,mower Deck Battery, and Electrical System

Next up, I install the mower deck, or in this case, the simulated mower deck.In some classes ( yes there are different classes of mower racing machines) you can install a replacement for the original mower deck as long as it is in the approximate location and height. Mine is made out of more of the steel square tubing welded into Cs with wire mesh tacked on top. This not only makes for a nice foot rest, but it is much lighter than the original deck. These are simply welded directly to the bottom of the frame.

Then I installed the battery, which was originally to go under the seat. The seat is sitting on top of the original bracket I welded directly to the top of the deck frame. But the battery was too tall. Its a small lawn tractor battery, and the ONLY place it would fit was right behind the engine. I welded two angle iron pieces pointing upwards to form a bracket in which the battery sits. The space is TIGHT. This actually works really well because it moves the center of gravity to the center of the mower, adding further stability.

Following that was the installation of the floor plates made of thick diamond plate. These were cut to size and screwed on with self-drilling screws so that both panels can be removed for servicing the RAGB, transmission. The fit was very tight and I glued on a piece of rubber to the battery to avoid abrasion from the diamond plate. The fit was perfect and snug, which is what you want with batteries.Diamond plate is costly stuff, so try and find scrap if you can. The same was done for the dash, which is where the electrical stuff goes.

That brings us to the next step, which is the creation of the electric panel. In order to keep everything neat and serviceable, all of the electrical components were screwed and bolted to the dash panel. This includes the starter button, starter solenoid, and tether switch.

Step 7: Puke Tank, Seat, and Engine Mounting.

Our next step is to make what is known in the racing world as the Puke tank. No- it isn’t for seasickness, but rather for the engine. Since the engine will be running at sometimes 50% faster than it was originally designed for, the crank case will sometimes spit oil from the crank case breather. Since you don’t want that stuff all over the track or you for that matter, you make sometimes called a puke tank. Mine is made out of ABS plastic pipe, brass hose fittings, and PVC for the breather on the right side (in white). This is mounted to the back of the mower under the seat, connected with a hose to the engine valve cover.

Next, I decided to machine slots into the engine mounting pan. I made keyhole shaped slots that enable the engine to be slid forwards and back so that the chain can be fitted and tensioned properly. This is the longest chain on the build, thus a spring-loaded tensioner was fabricated in addition. Since the chain here is hanging horizontally, you want to have constant, gentle pressure applies to keep it from falling off. The tensioner is simple, using a channeled nylon idle pulley typically used on mower decks. Like the skateboard wheel, nylon holds up just fin on chain. The pulley is mounted to a arm that is bolted to the underside of the simulated mower deck via a nylock nut and bolt. A spring is attached to it as well as a bolt welded to the underside of the engine pan. As you can see, the chain fits nicely from the centrifugal clutch to the RAGB.

Now the seat. This step is actually kind of important. You’ll find that staying on these mowers on a bumpy dirt track with sharp corners is difficult.The inertia will threaten to throw you off. But at the same time, if you do fly off, you want to clear the scene of the accident and not get run over by your own mower. So it needs to be low. The solution is to have a low seat with low sides that keeps your rear attached to the seat. It’ll actually give you more control. One last word- it helps to have padding. A steel seat with no padding can be. painful. My Wife covered mine with upholstery from an old chair.

Step 8: Engine Modifications and Installation.

Now that the chassis and other vitals are now complete, now its time to work on the engine. The engine I’m using is a 12.5 HP Briggs and Stratton with a cast iron sleeve. These are one of the most common engines on riding mowers. Mine in particular is what’s known as a flathead because the other variant has overhead valves. These engines are extremely simple and inexpensive. The flathead takes up less space too.

But to use an engine such as this stock would be a mistake. First of all, the governor will be removed. enabling engine speeds to approach double what the engine was designed for. This means that parts are going to take a severe beating and certain items should be replaced. First and foremost- the flywheel. The original is made out of solid cast iron and weighs in at 12-15 pounds. Cast iron is somewhat susceptible to fracturing from stress. Even microscopic cracks, not seen by the naked eye can cause a flywheel to explode at high speeds. While this rarely occurs, its something to think about since the flywheel will be less than a foot away from you.know-what. There are two fixes, once better than the other. The first is to make a scattershield, which is a 1/4 frame made to fit around the top of the engine shroud. These can be bought at a number of sites, including G-team racing. These will at least contain the explosion if it occurs, but not absolutely.

The safer, albeit more expensive solution is to purchase what’s known as a billet aluminum flywheel. These are milled via computer guided mills out of solid billet aluminum- the stuff used to make aircraft components. Not only will the wheel be lighter, but stronger and almost indestructible.Considering the cost of the milling machine, the cost is reasonable. Around 350.

Next, the governor is removed. You want to remove it entirely, including internally. That involves removing the oil pan. You will see a brass sleeve in which the throttle lever slides through. After you remove the throttle, use a punch to remove the brass sleeve. To seal the hole, I simply use a bolt and a nut, washer, and rubber o-ring.

The second specialized part is what’s known as a dogbone connection rod for the large cast iron counterweights. These large weights help the engine run smoother. The crank runs directly through it. The wimpy aluminum factory original is prone to breaking. If that happens, the counterweight will slam into the sides of the crank case, breaking right through it. Say bye-bye to the engine if that occurs. So again, a billet aluminum replacement is used.

Additionally- as mentioned in the new updates section, the stock piston rods in these engines do not deal well with the additional engine speeds. So as a recommendation, invest in a billet aluminum rod. You will also have to buy another piston, most often being a magnesium Briggs unit. I ordered mine from a company called G Team racing out of North Dakota. They are well worth the money not having to worry about an engine blowing out on the track, which trust me- is rather scary and potentially costly.

Next, the linkage for the carburetor needs to be setup. For the gas throttle, A bicycle brake lever and brake line is connected to a spring that pulls against the throttle control of the carb. The pull of the spring is what snaps the brake lever back in place.The lever is attached to the steering wheel. As you can see, I simply bent two scrap pieces of diamondplate aluminum. These face each other. On one side, the spring goes to the throttle lever of the carb. The brake cable comes from the other side, attaching into the same hole as the throttle spring. To hold the brake cable in place, I used a brass nipple fitting that stops the cable sheathing, but allows the actual cable to come through. The spring holds the cable into position.

Lastly, I fabricated the exhaust system. It is a 2.5 foot long pipe. To get the correct curves, I bought a muffler header pipe that is made to fit a Snapper riding mower from a mower parts supply site- cheapmowerparts.com This will fit 8-12 HP engines, hence it fits mine. This is cut and a second curved piece was made from the exhaust pipe of a 1980’s Honda Civic( which apparently had tiny exhaust systems). These two curves gave me the right geometry to curve out and under the foot rests. The end of the pipe is simply a length of straight muffler pipe. These are held to the bottom of the foot rests via pipe hanging brackets used for electrical conduit. By the way- this exhaust will make your engine extremely LOUD. Just a word of warning in case you have. neighbors. close by.

Step 9: Paint and Finishing It Up.

Now for the funnest part of the build: Painting. Now all of that hard work gets to get shown off. But before painting, you need to do some prep. The chassis is likely oily and dusty from welding. All of the welds are also likely not clean meaning they’re splattered. You can quickly clean up the frame with sandpaper flap discs attached to a grinder. Clean all of the rust, splatter, and rough edges to a smooth surface.

I used a oxide primer primer, which is a good foundation for the paint. I used plain ole’ black spray paint. I chose spray paint because the frame is very likely going to get pitted with rocks and future mechanical modifications. So it can easily be touched up. Plus its cheap. The fiberglass hood was painted with orange engine paint, which I find dried quick and smooth.

Now the entire mower is put back together. Wheels, engine, brakes, electrical, etc. The mower went back together surprisingly quick. Less than two hours was all it took.

With the mower put back together, all that’s left is to bleed the brakes, install the battery, fill the engine with oil, and then give her a test run.

Wanna’ see it run? Watch the video.

Anyhow, it was lots of fun making this mower and so far I’ve been in 3 races this season. Feel free to ask questions if you want to make your own. if you want to see me in action, visit my racing club’s web site, http://www.pvmowerracing.com

Step 10: Updates.

Its been a year since this mower was completed. After a year of racing I’ve learned what the weak spots were on the machine. First, stock pistons in Briggs flathead engines do not hold up well under stress. I wound up blowing two engines early in the season when the rods snapped. So the first improvement was in purchasing a billet aluminum rod and a lightweight magnesium piston. So far this rod has held up well under the stress.

Secondly, any nuts and bolts that can come loose will come loose unless they are secures using nylock nylon lock nuts and loctite ( the blue bottle). Otherwise the severe track vibration will cause things to fall off, which they did frequently. So spend the few extra dollars and secure everything down and save the headaches.

Lastly, the cheap stamped bearings I went with in the steering system have way too much slop in them. I replaced all 8 of the bearings with sealed ball bearing units with steel snap rings. This removed all of the slop in the steering and made the handling much more accurate and responsive, which in turn is much safer. So make sure and invest in better high quality bearings for everything that moves.

Oh yeah- one more thing- Orange was not a good color. So now it is all-black.

The video is of our first event of the year. Enjoy!

Step 11: Updates: New Rear Axle Chain Tensioner.

Here’s another update, and this time its again for the rear chain tensioner. I had a lot of issues with the chain jumping off the sprocket for the rear axle. I tried a few things, namely the experiment I mentioned in the previous step involving two roller skate wheels, one on top of the chain, one underneath. That system didn’t work.

So I came up with a new tensioner that involves using a chain sprocket idler which is spring loaded. The old tensioner idler was mounted to a bracket with a slot cut in the side to enable the idler wheel to be moved up and down. This is shown in step 4. So I used the same bracket but instead of having the idle sprocket be stationary, it floats up and down in the slot with the help of a sturdy spring that ensures that it keeps constant pressure on the chain. I accomplished this by using 2 large fender washers on each side of the mounting bolt going through the bracket, then having nylock stop nuts on either side, backed up just enough to allow the mounting bolt to move freely up and down. I welded a bolt to the frame above the idler sprocket so that the tension spring could be attached. The idler sprocket itself is mounted to a thick piece of 1/8 steel.

This has worked out great all season. The tensioner can not only move up and down, but also slightly forward and back thus not matter what the chain does, the tensioner keeps constant pressure on it. With both chains staying put, the mower is now pretty reliable.

The rebuilt engine has held up great this year. Its now broken in so the synthetic oil stays almost crystal clear for a good 2-3 races.

We also just redesigned our web site and you can check us out at www.pvmowerracing.com

Step 12: Updates for 2011: Total Overhaul

After over 3 years of racing the mower with the same configuration it was time for some serious upgrades. There were some major shortcomings with the old design. That and as the years went by, others on my team upped the anty and had upgraded their machines. A lot of things have changed in mower racing since I built this machine. A lot of custom, high performance engine parts are now available making more durable, highly reliable engines that can withstand higher RPMs over longer periods.

Before we begin read this : I’ll reiterate a bit about safety. As I mentioned at the very beginning of this insctructable, racing mowers are actually pretty dangerous and if you’re not careful you can very easily get hurt. There are several racing organizations out there that all have very specific rules and regulations as you’d find in any motorsport: Rules meant to keep the driver and those watching safe. Think of these as go-carts except they look like mowers. We have no safety cages or restraint systems. Thus you must wear correct safety gear like a DOT approved helmet- preferably a full face helmet. You must also wear gloves, boots, long pants, a neck collar- or even better- a neck brace. Your mower must also have various safety features like real brakes ( not the crappy ones the mower came with), a safety tether that cuts power if you fall off, and others as well. In order to understand these in detail visit www.heymow.com and check out the rules. If you show up at an event and you or your mower are not equipped safely- you won’t be racing. Lastly. DO NOT simply take the ole’ family mower and make it go fast without anything else other than swapping pulleys. Stock mowers are meant to go 2-5MPH. Not 50MPH. If you do something like this, you will have a greater chance of getting injured.

Lastly, if you’re welding, drilling, grinding, or working with any power tools, please use proper safety gear- as in gloves, boots, goggles, respirators, and so on. Use common sense and you’ll avoid a trip to the emergency room ( trust me- I’ve been there enough to know) Whew! Now that that’s over- let’s get goin’!

The changes I made to the mower were as follows: 1: Extend the length of the frame. Why? The original frame was around 38 long. The width from wheel to wheel? 36. The problem was that when you’re basically driving a square, you have very poor handling. I decided to lengthen the frame to the maximum length permitted for Mod-X machines: 42. Thus I would add 6 to the frame.

2: New engine with a plethora of high performance parts. This includes a billet rod, billet ARC flywheel, High-torque starter, billet crank with built-in lightweight counterweights, a high performance cam, Higher strength valve springs and better valve keepers. That and the rings would be filed to an absolute close tolerance to increase compression. Other considerations would be porting and polishing. The old engine was a very mild build. This new engine was a total build-out. As this was my first major mod job of an engine, there was a lot of learning.

3: New sheetmetal. Luckily I found a donor mower pretty quick.

Husqvarna Craftsman Hydromatic Shifter Adjustment

4:A new fully adjustable steering system. The old setup wasn’t adjustable at all. The new one is fully adjustable and the caster and camber can be carefully tweaked. This is important because no matter what engine you might have, a mower that steers poorly and plows into corners will be impossible to handle.

The first thing was to strip the old mower down. After 3 years of abusive tracks and racing, it was actually in pretty good shape. Most of the parts I’d used like the brakes, wheels, axle, transmission, and clutch could be re-used, which mean a lot less money. The old 12.5 Briggs Flatty served me well but will be replaced with a 14.5 Briggs Overhead Valve engine.

I had previously gone to a scrap metal yard and gotten a piece of channel iron to extend the frame 6. The frame on mine is a simple box frame with a tubular frame up top. Thus I was able to extend my mower versus something like a stamped steel machine, which would be more problematic. The channel iron was cut and the frame was sliced near the front. The idea was to preserve the more complicated rear of the machine which has the engine, transmission, and brake system mounts so it could be used as-is without modification. These new pieces of angle iron was welded into place.

Since the old fiberglass hood was now way too short for the now-lengthened mower, I needed to either cut and extend the old hood or find a new hood. Luckily for me, the group leader or our group has what I’d call lawn mower heaven in his back yard- a whole fleet of old riding mowers. One was an old Montgomery Wards and the hood and fenders from it fit perfectly! Easy.

Step 13: Update the Old Steering System to a Fully Adjustable One.

Perhaps the single most important thing you can do for a racing mower is get your steering right. Before I go into the build, let’s talk a little about steering geometry because if you understand how it works, you’ll have a much easier time building one. I have to admit it took me a long time to figure it out. The guys I race with in many cases raced stock cars thus they have it down to a science.

Basically the problem that we have on the track is that the rear axle doesn’t have a differential. As such both rear wheels are traveling at exactly the same rate. With a differential the outer wheel naturally travels more than the inner, thus making turning into a corner easier. In order to correct this problem, you’ll want to remove weight from the front right and place that weight onto the front left so that weight is removed from the right rear. In doing so you’ll offset the effects of having no differential. This is done so by adjusting three things: Caster ( the angle that the spindle sits- either positive or negative, the Camber- the angle at which the wheels lean in or away from the mower, and toe out- as in how much the wheels point away from the mower. We’ll go into this later when final adjustments are made.

The old spindles were cut off of the front axle. I re-used the old axle instead of installing a new one. The new spindles are fully removable from the axle and are mounted with large heim joints. The mounting plates for the spindles are welded to the ends of the axle and have machined slots so that the spindles can be turned forward or back ( which gives you your caster adjustment). These plates need to be welded to the ends of the axle at a 10 degree angle with the tops of the plates pointing in towards the mower. This is critical because this in turn gives you your camber- or the degree in which your wheels will lean in towards the mower. Having this adjustment will allow you to carefully adjust the camber in such a way as to help push more weight onto the left front wheel meaning you will be able to hook up more easily in the turns.

With the mounting plates welded in place, the spindles could be attached. These spindles come in a kit and you can get them from various go-cart suppliers. Some people make their own spindles using bolts. If you do that make sure to use Grade 8 bolts as they are less prone to bend than conventional bolts.

The last major thing you’ll have to do is to attach the spindle arms for attaching the radius rods. There’s a pretty simple method for doing this: With both spindles absolutely straight on both sides, attach a piece of string from the ends of the spindle mounting bolts and attach the string to the center of the rear axle. Weld the spindle arms as if you are lining them up with the path of the string. Easy enough.

Once the steering system is installed, you’ll have to do some adjustments to the setup to ensure the mower is handling properly. But that will come later once the machine is completed.

Step 14: Porting and Polishing the Engine.

Porting and Polishing

The next step was to start working on the engine. The engine I got was a early 90’s Briggs 14.5 OHV. There are a lot of similarities between it and the old 12.5 flathead I had. The crank, piston, rod, and carb in the 12.5 are basically the same. Thus I was able to scavenge the old magnesium piston and billet rod I’d been running. The rod is an ARC rod and has replaceable bearings. Its always important to replace these if you’re sticking them in a new engine. I also ordered new rod bolts.

I’d also decided to try out a new product from ARC, which is a billet chrome molly billet crank. Just as I got started on the engine they came out with it. For years we’ve had a dilemma where the old heavy cast iron counterweights that came with these engines not only presented an issue of having to deal with more mass, but on occasion these have come loose, smashing through the crank case. The solution was to get an old-style 80’s or early 90’s crank with removable eccentrics and install lightweight brass counterweights. ARC developed a billet crank with the counterweights machined into the piece- thus its all one piece. I opted for this part.

Also ordered was a new set of valves and more modern valve keepers. The old style of keepers uses a sort of cap with a slot cut in the top. These have been known to come loose out on the track- causing damage to the head. The new keepers are similar to ones you’d find in a car and are highly unlikely to come loose.

Lastly, while I thought I would be able to re-use my old billet aluminum flywheel, the one I had was solid aluminum-including the hub. The hub was badly damaged from having slipped numerous times on the crank. I ordered an ARC billet flywheel with a removable steel hub- thus making it also adjustable. In doing so I also had to order a high-torque starter. The starter looks like something you’d find in a car also. Its made by Denso- the folks that make parts for Toyota.

Anyway, one way to increase engine performance is to do something called porting and polishing. What this entails is to basically provide an easier way for gasses to enter and exit the engine. From the factory the intake and exhaust ports have rather sharp edges. Run your finger inside the area where the port enters the valve area and its almost sharp enough to cut you. These edges will need to be shaved down and smoothed over. I used a stone mounted to my Dremel tool to slowly cut and blend these areas so that the airflow would be smoother. I then followed up with some polishing compound and gave it a mirror polish. This took hours but its worth it in the end.

Step 15: Building the New Engine.

Building the Engine

With the parts all ordered and received I spent about a week building the engine. One thing I did was ordered a set of over-20 rings. This means that the gap between where the ring when it is fully compressed in the cylinder is.020 over the stock gap. This is done for a few reasons. Mainly its if you had an engine with a worn cylinder and needed more available ring to fill that void. The ends of the ring are then filed down until a desired ring gap is met. In my case I did this to intentionally make the ring gap far tighter than stock. Usually a stock engine will come with a 0.10-0.20 ring gap. In my case I wanted to have a 0.004-0.006 gap. This would give me more compression overall. Doing this is tricky if you’re like me and don’t have a ring grinder tool handy. But it can be done. Simply mount a mill file in a vise straight up and down and very slowly pull up on the ring with the end of the ring filed as level as possible. Only file one side of the ring too because doing so means a greater chance of having an uneven gap. Every few strokes put the ring in the cylinder and tamp it level with the top of the piston. Measure the gap with a feeler gauge. Eventually you’ll arrive at the correct gap. I accidentally filed too much and wound up having it down to a.008 gap. Ooops. Not that big of a deal so that’s what I installed it as.

The crankcase was thoroughly cleaned and the hole which the governor lever came out of was blocked using a bolt and nut. The next step was to install the new valves. In addition to ordering new valves and keepers, I also ordered a stronger set of valve springs. These are double layer springs with a smaller inner spring that is removable. What I wasn’t aware of was that you don’t want to use the center spring. I spent hours sweating bullets trying to install the new valve and keepers because the dual springs were so stiff. The first time I did this I was pressing the spring down with a socket when it slipped. The tiny keepers flew off into the wild blue yonder, never to be seen again. What a pain! I never found them as they were hopelessly lost somewhere in the shop. Thus I ordered 3 extra sets. With the center springs removed it was much easier to push them down and drop in the keepers. Slowly let the pressure off the springs and the keepers will usually fall into place around the groove of the valve stems.

With that done it was time to install the piston and rod. The rod needs to be installed using exacting torque settings. The final is @ 28 foot pounds. First, apply a bit of oil to the bolts. This will enable you to do what’s called Wet torquing. Using a torque wrench, set it for 16 foot pounds. go back and forth from one bolt to another until you arrive at 16 foot pounds. Then go in 4 pound increments until both are snugged to 28 foot pounds. This is vitally important. Incorrect torquing can mean a snapped rod.

Step 16: Building the New Engine, Part 2.

Engine Building.

Next up was the installation of the ARC billet flywheel and high torque starter. In regards to the flywheel its important to understand that the flywheel is mated to the crank via a friction fit. There is a key but all that key does is provide the means to properly align the flywheel magnets to the magneto. In order to get a tight fit, especially with 2 new parts, you need to do something called lapping. Simply put, it consists of using a very fine abrasive to mate the two pieces together. You can actually buy lapping compound to do this. Simply smear a bit of this onto the crank, place the flywheel on the crank and twist it back and forth. You don’t have to do this all that much. Just enough to make sure that the two pieces will be perfectly matched. Clean off the compound and then torque the flywheel down with about 100 foot pounds of torque. You do so via an air impact wrench.

Once you install the flywheel you’ll need to install the starter. This is a bit tricky with the high torque starter. You don’t want the teeth of the starter to be too tightly meshed with the ring gear of the flywheel. If you do this the flywheel will bind. The starter comes with a number of thin washers that you use as shims. Unlike typical small engine starters, this is more of an automotive starter and you can’t just walk the starter gear up. Instead the starter gear is tucked down out of sight. Why should you care? Because in order to get the proper gap between the ring gear and starter gear that starter gear needs to be pushed up all the way. Here’s how you can do it ( or at least how I did it). Get a small hex key, stick the short end of the hex key behind the starter gear and pull UP. With the starter gear fully pulled up, stick another hex key under the starter gear so that when you release it it won’t snap back down.

Now you’ll want to hold the starter up to the flywheel. Stick the 2 mounting bolts through the starter and into the threads in the side of the engine. Here’s where it gets fun. Get a paper clip. Not a weanie one either- but a large paper clip. bend the end of it down and measure the gap between the valley of the ring gear and the tip of the starter gear. The proper gap is the width of the paper clip. In order to make this work you’ll need to insert enough washers to get the correct gap. Doing this was a pain in the ass because the washers kept falling from the ends of the bolts as I tried to hold it up to the engine. It took around 3 washers on each bolt for mine to get the correct gap.

Now that we’ve finished doing that its time to install the blower housing. You’ll see right away that the ARC wheel is not as tall as the stock unit. As such the fins fall short of the blower housing by over an inch. This is not acceptable because air won’t be getting sucked into the engine cooling fins and you’ll very quickly fry the engine- ruining all those lovely high performance parts. So, as un-fun as it is, you’ll have to cut enough of the shroud to get the flywheel fins within 1/8 of the blower housing. I measured from the top of the fins to the blower housing. I marked the amount with a permanent marker around the bottom of the blower housing and used a grinder wheel to cut it off. Again, you’ll want to make sure that you have about 1/8 of clearance from the blower housing to the top of the flywheel fins.

With most of the engine together its time to install the tins and the breather plate. I re-used the plate I’d made for the old 12.5 flathead. The stock breather plate will not work. You need something that will not leak and one that will allow more air to pass through. Thus the steel plate I made has a threaded piece of pipe coming out of it with a brass barb screwed to this. I usually use a gasket making material- usually the blue stuff- and barely tighten the bolts. You’ll want the gasket material to harden before you snug down the bolts. As far as the tins, there have been some people who for some reason don’t re-install these. Without them the engine won’t cool properly. So make sure and install them and make sure they’re not bent. With that the engine is done- minus the carburetor.

Step 17: Installing New Chain Tensioner.

Chain Tensioner.

One of the biggest problems I had with the old mower was the rear axle chain setup. The chain repeatedly either came loose or snapped. This might have been due to the old chain being a #35 size, which is a bit small. I elected to upgrade the chain to a #40 size which meant new sprockets. At the same time I also installed a new RAGB transmission. The old one had always had a lot of play and slop in the gears. This never caused a problem. But I decided to install a duplicate I found on Ebay a year ago. The old one will serve as a spare.

The key to having the rear chain not fall off is the correct combination of proper alignment and tension. All chains will stretch as they wear. Thus the best setup involves a spring-loaded idler. In this case I used a idler sprocket. The fatter chain meant that it would be hitting the top of the transmission mount. The old #35 barely cleared it. Thus I had to cut out one side of the mount and weld a new piece behind where that piece had been. Thus the mount was staggered back enough to allow the chain to clear.

A great deal of time was spent ensuring that all 3 sprockets were absolutely aligned. This is done with a flat steel ruler. Since the tranny is more or less not adjustable the idler and rear axle sprocket both needed to be aligned with the tranny sprocket. Lay the ruler flat over all 3 sprocket surfaces in such a way as that all of the gear’s sides are totally flat- as in the ruler lays flat across all 3. Gently tap the sprockets until this happens. This needs to be absolutely perfect so spend some time.

The tensioner I use is one I made 2 years ago. I modified it to use the larger idler sprocket. I also relocated the tension spring in such a way as so it pulls directly up. Previously the spring was pulling slightly forward, which I think might have caused the idler to jump off the chain. The tensioner itself rides in a slotted piece of square tubing. A bolt runs through the slot and thus allows the entire tensioner to float up and down. The spring keeps the tensioner against the chain. As such even if the chain stretches, the tensioner will always apply the same amount of pressure.

Step 18: Re-doing Exhaust, Paint, Brakes, and Other Stuff.

Finishing up

Something I realized right away was that the engine was reverse of what the old 12.5 engine had been: The starter, carb, and exhaust were all on the other side. At first I didn’t think this would be that big of a deal. But the problem was that the new high torque starter stuck out so far on the right that it interfered with the brake pedal- which was on the left where the starter would now be. This meant moving the brake pedal and master cylinder to the left. This wasn’t that difficult: The MC was moved to the left and new holes were drilled for its mounting bolts. The problem arose when I realized that with the carb on the left the intake was extremely close to the brake pedal. I didn’t want to accidentally kick the carb when racing. After doing some configuring I simply welded an extension onto the end of the pedal making it wider. A piece of angle iron was welded to the top of the pedal. This ensures that my foot will not slip and wind up sliding close to the carb. After 2 races its worked out well.

The exhaust was a bit tricky. Since the exhaust was on the other side it had to be cut so the bend could be reversed to face the other way. On top of that the exhaust port was higher up than the one on the engine. In order to accomplish the additional length I welded in a piece of pipe. A word of warning: Do not weld galvanized steel. The pipe I used was galvanized but I spent a great deal of time grinding this off. If you do weld Galvanized you can get very sick.

The engine was then installed and the old clutch bolted on. This has been a fantastic clutch with over 3 years of use and hardly any wear. I did disassemble it and applied a very light coat of grease to the bearings. I also cleaned the shoes a bit.

The new hood and fenders were sanded down and painted. I used Duplicolor high heat ceramic engine paint. For some reason I’ve found its one of the best rattle can paints for getting a nice smooth finish. The color I got is called Cast Iron. Pretty cool actually, and different from what most people use on their racing mowers. Seems like crazy fluorescent colors are very popular.

Step 19: Finishing Up and Final Adjustments.

Final Adjustments

With all of the sheetmetal painted the mower was fully assembled. Pretty nice looking if I don’t mind saying so. Now there was only one thing left to do- which was to race it and see what it would do. The first race was actually what we call our Test-n-tune day where all the new mowchines are brought out and tested. and tuned up.

Mine had some serious handling problems. The mower was pushing into the corners. It was so bad that I could barely stay on the track. As it turned out my steering system was wayyyyyy out of whack. To fix this I did some serious adjusting. This involved doing a few things:

1: adjusting the front right wheel so that it had more camber. As it turned out I had somehow welded the right spindle mount on at the wrong angle. Luckily all I had to do was simply thread the top heim joint inward until the camber was corrected. The right wheel was also dropped downward a bit. This enabled the right front to push down onto the front left.

2: Adjust the toe-out. As mentioned before, toe-out means how much the wheels splay outwards- as in they turn away from the mower a bit. It doesn’t take much. Only 1/8 on each side. Doesn’t sound like much but this will greatly help the mower become far more stable.

The first real race we had was a huge difference. The mower did much better. That said, there are still some issues. The biggest is that I chose not to install a high performance cam. This would greatly help with low end torque and faster acceleration out of the corners. This is relatively simple to do and only involves removing the bottom of the engine. I’ll decide on what to do about this soon.

In the meantime if you want to see the mower racing in action, check out our racing group’s web site which is chok-full of videos. www.pvmowerracing.com

Thanks for reading and stay tuned for even more updates!

The Best Self-Propelled Lawn Mowers in 2023 for Making Your Yard Work Easier

These lawn mowers drive themselves, taking the load off you in the process.

By Roy Berendsohn Published: Mar 21, 2023

One of the perks of the warm-weather season is getting to spend time outside. If you own your own home and have a yard, it’s very likely that in order to enjoy your outdoor space, you need to mow the lawn. The larger the yard, the more work it will be to maintain. If you have a lot of grass to cut, you’d be wise to consider a self-propelled lawn mower especially now that there are a ton of sales just in time for Memorial Day.

The primary difference between a standard push mower and a self-propelled mower is that the former moves when you push it, and the latter essentially moves itself with only your guidance. Once the engine is running, all you have to do is squeeze a handle or push a lever and the mower will start moving forward with you as you walk.

Turning the mower around is your job, but once you have your heading, just keep the drive handle squeezed and escort the mower down the path, no pushing necessary.

Self-propelled law mowers take power off the engine and route it via a belt to a pulley on the transmission and axle. When you move the drive control lever on the mower handle, you tension the belt, causing the pulley to turn, and this drives the transmission, moving the mower forward.

Move the drive control lever back and the tension is released, the pulley stops turning, and the mower stops moving forward. The belt-driven transmission is a time-tested design to power the mower and take the load off you in the process.

What to Consider

A mower is like many consumer products in that the more features a manufacturer adds, the more expensive it becomes. But a longer or more eye-catching list of features isn’t necessarily better. Sometimes less is more. Here are the most important to keep in mind.

Front-wheel drive mowers tend to be less expensive than rear-wheel drive units. They can be easier to turn because you don’t have to disengage the drive wheels to do so. Simply push down on the handlebar to raise the front wheels off the ground. However, their traction isn’t as strong on hills or when the bag is full, as there isn’t as much weight over the drive wheels.

Rear-wheel drive mowers do cost more and aren’t as easy to turn, as you do need to disengage the drive—but this isn’t too much of a hassle. Rear-wheel drive mowers shine on hills and inclines, and when the grass bag is full. In either scenario, weight is shifted rearward and over the drive wheels, which enables superior traction, thus making the self-propel more effective.

An engine as small as 125 cc can power a mower, but most are somewhere in the 140 cc to 190 cc range. A large engine helps when powering through tall, lush grass or in extreme conditions, such as with a side discharge chute in place and mowing tall weeds in a border area. Also, the extra torque provided by a larger engine can improve bagging when the going gets tough (tall, leaf-covered grass in the fall). But if you mow sensibly and pay attention to deck height—and especially if you don’t let your lawn get out of control—an engine between 140 and 160 cc has more than enough power to get the job done.

A mower can have all four wheels the same diameter (7 to 8 inches), or it may have rear wheels that range from 9.5 inches to 12 inches in diameter. Larger rear wheels help the mower roll more easily over bumpy ground.

With some mowers you can start the engine with the twist of a key or the press of a button. It’s a great option, but a luxury. Keep the mower engine tuned and use fresh fuel with stabilizer added to it, and you’ll never have trouble starting.

Any number of mechanisms can control a mower’s ground speed—a squeeze handle, a drive bar that you press forward, even a dial. There’s no single right answer here. Look at the design and think about how you like to work. For example, if more than one person will be using the mower (and not all of them are right-handed), a drive control like that on a Toro Personal Pace mower might be the answer. Just push down on the bar to make it go faster. Let up on the bar to slow down.

A mower that can bag, mulch, and side discharge is known as a three-function mower, the most versatile kind. Two-function mowers bag and mulch or mulch and side discharge.

Mowers will typically have one, two, or four levers to control the deck height. Single-lever adjustment is the easiest to use, but it requires more linkage, which adds weight and complexity. If, for some reason, you find yourself varying deck height frequently, it’s a good option. Otherwise, two or four levers work just fine.

Only Honda makes a gas-engine mower with a high-impact plastic deck (there are battery mowers that have plastic decks). Otherwise, mowers generally have a steel deck, and a few manufacturers—Toro, for one—offer a corrosion-resistant aluminum deck. An aluminum deck won’t rot the way a steel deck will, but you still need to keep it clean.

This is a hose fitting mounted on top of the mower’s deck. When you’re done mowing, hook up a hose and run the mower to power wash the underside of the deck. We’ve had mixed results with these, but they’re better than just letting a mass of dried grass clippings accumulate.

expensive mowers come with a more durable bag with more dust-blocking capability. If you bag a lot, especially leaves or other lawn debris in the fall, then you need a mower with a higher quality dust-blocking bag. Having said that, if you rarely bag, the standard one that comes with a mower will last you the life of the mower.

Also called wide-area mowers, machines in this subgroup help homeowners better reconcile their need for more power and speed with the fact that they may not have enough storage for a tractor or zero-turn mower. A typical residential walk mower has a single-blade deck that cuts a swath from 20 to 22 inches wide. Wide-cut mowers (built for homeowner use) have either a single blade or, more typically, a pair of blades, cutting from 26 to 30 inches with each pass. Some of these are rated for light commercial use and have larger decks, in the 32-inch range, and engines that start at 223 cc and go up to about 337 cc.

Wide-cut mowers typically employ gear or hydrostatic drive transmissions, and they have top speeds of about 4 to 6 miles per hour. At their fastest, they move so quickly you have to trot to keep up with them. Needless to say, they’re overkill for small yards; only opt for one of these if you’ve got a significant plot of land that you need to keep tidy, but not one so large that you’d be better off going with a full-on riding mower.

How We Tested and Selected

We compiled this list based on Popular Mechanics mower testing and our knowledge of the lawn mower market at large. For our testing, we put mowers through the paces using our standard Popular Mechanics methodology: We cut turf grasses such as fescues and blue grass and rougher non-turf grasses like Timothy, clover, orchard grass, and wild oats, all in both normal and shin-deep heights. We mow uphill, downhill, and across the faces of hills. The maximum slope we cut is about 30 degrees.

That may not sound like much, but it’s about all you can do to stand on it, let alone push a mower up it or across it. We mow damp and wet grass to test general cutting performance and whether clippings accumulate on the tires. And we cut dry and dusty surfaces to see how well the bag filters under less-than-optimal conditions.

Honda HRN 216VKA

Key Specs

Honda mowers enjoy a sterling reputation. Having tested their walk and self-propelled mowers for the last 30 years, we feel confident that Honda’s entry level mower is a great choice for homeowners looking for power and durability. The HRN features a GCV 170 gas engine that’s built to withstand long hours of operation.

If you do your own maintenance (and most owners who buy this class of product do), you’ll appreciate the easily accessible spark plug and the fuel shutoff valve that enables better winter storage. Close the fuel shutoff and run the mower until it sputters to a halt. This will clear the carburetor of any gasoline, which will prevent the ethanol in it from disintegrating and causing running issues later on. Open the shutoff valve in the spring, add some fresh gasoline, and the mower should start easily.

All this maintenance stuff is great, but we can also tell you that our past test findings on other Hondas prove that their cut quality is outstanding for cleanliness. Sharp blades deliver a velvet-like finish. And their bagging ability is also quite good, in the same league with other well-bagging mowers from Toro.

In all, if you take mowing seriously, you should enjoy this Honda. If you have a little wiggle room in your budget, consider the Honda HRX, which features a mower powerful engine and a composite deck that won’t rust and is renowned for its durability.

One note is that Honda has announced that it will cease selling lawn mowers in the United States after this year—so if you’re considering buying one, best do it sooner rather than later.

Toro Recycler 60-Volt Max Lithium-Ion

Key Specs

Toro mowers have garnered more recommendations from us than any other brand for two reasons: build quality and cut quality. These were amply demonstrated in our testing as the Recycler turned in the best ratio of cut area per amp-hour of battery in the self-propelled category, while at the same time not skimping on cutting, mulching, or bagging quality.

We attribute this outstanding mower performance to three features, all upgrades to the previous version of this machine. First, the air vent at the front of the mower deck seems to improve mulching and bagging performance. Toro calls it Vortex technology, a design that increases air flow under the deck. This helps to stand the grass for a cleaner cut, which improves mulching performance, and also allows better airflow into the bag when collecting the clippings.

Next, the company’s redesigned “Atomic” blade configuration appears to assist the air flow and clipping movement. Finally, the three-phase, 60-volt motor is exceptionally efficient, resulting in a large cut area for a single battery.

Toro has maintained features that make this mower work: rear wheel drive, a one-piece deck that’s all steel (no plastic nose), 11-inch wheels to help it roll over roots and crevices, and the same fold-forward handle that was an industry breakthrough when it was introduced some years ago.

Ryobi 40-Volt Brushless Self-Propelled Mower

Key Specs

This is one of Ryobi’s top-of-the-line mowers, and it’s American-made construction is something we wish we saw more of. It delivers a tremendous cut area with its two 6-Ah batteries providing a total of 12-Ah of capacity, and its X-shaped blade leaves a pristine surface in its wake.

Ryobi estimates the design should provide 70 minutes of run time; we didn’t time our cut, but it strikes as plausible. Its rear-wheel drive and reasonably aggressive tire tread pattern provide good hill climbing and sidehill cutting performance, and its bagging on all surfaces (level, sidehill, and uphill) is also commendable.

Other ease-of-use features include an easily installed or removed bag that mounts and dismounts straight up and down through the handle; deck adjustment is quick and easy thanks to a single-level deck height adjustment. The straight edge deck is polypropylene; it will never rust and needs very little care other than basic cleaning.

Toro TimeMaster 30 in. Briggs Stratton Personal Pace

The Toro Timemaster 30-in. mower has been around for several years and has earned a reputation as a sturdy workhorse for homeowners who want to cut down on their mowing time. It’s also used by some professionals as well. A few years ago the Timemaster got a slightly more powerful Briggs and Stratton gas engine, so it should have no issues powering through most demanding mowing jobs.

The Timemaster is rear-wheel drive and features Toro’s Personal Pace drive system that’s used on many of its self-propelled mowers. This allows the mower to move at your speed by simply pushing down or releasing the handle, which is spring-tensioned.

With a 30-in. deck, Toro claims the Timemaster will help you reduce your mowing time by about 40% compared to using a standard-sized mower. You can mulch, back, or side discharge with the Timemaster, and the handlebar can be locked in a fully vertical position to reduce space consumption in storage.

If you have half an acre to a full acre of lawn to mow and prefer the experience of a walk-behind mower versus a tractor or zero-turn, the Timemaster is worth a look.

Craftsman M220

Key Specs

Craftsman mowers have been doing very well in our tests, so we can recommend this one because it’s so much like the many other of the brand’s models that we’ve tested. If you’re looking for a good blend of maneuverability and power, you’ll get it with this mower. Its front drive helps move it along and makes it easy to turn.

It’s important to note that front-drive mowers do lose some traction when running uphill, particularly with a full grass bag. But if your slope is less than 20 degrees, and you’re not bagging uphill, you’ll be fine. The side discharge will also help you handle tall grass. Adjust the two deck levers to bring the mower up to full height and have at the rough stuff.

The fact that this mower bags, mulches, and side discharges is a plus, enabling you to handle a wide range of mowing conditions, from early spring and late into the fall. Three-function mowers like this are our preference for that versatility.

Toro Super Recycler Self-Propelled Lawn Mower

Key Specs

This is a beauty of a mower, with a cast-aluminum deck and a smooth-running Briggs Stratton 163-cc engine. We tested the Honda engine-equipped version, and it was effective at both bagging and mulching, even in moist grass.

Equipped with rear-wheel drive and the Personal Pace system (the farther you push the drive bar, the faster the mower goes), it’s an effective hill climber and moderately effective on sidehill cutting. It has relatively small 7.5-inch tires on all four corners, which causes this Toro to bump up and down a bit on washboard surfaces. But the good news is that it’s equipped with a far higher quality tire than we’re used to seeing these days. We didn’t notice them pick up any grass on moist surfaces.

Other features we like include its forward-fold handle that has a built-in shock absorber that Toro calls a Flex Handle Suspension, and a high-quality grass bag that loads through the handle, from the top.

QA

Are there special maintenance considerations with self-propelled mowers?

Yes. Both front- and rear-wheel drive mowers typically feature a drive belt, which can crack or wear out over time. Fortunately these belts are not difficult or particularly expensive to replace.

Secondly, you may have to replace the drive wheels occasionally. These wheels are driven with gears. there are typically teeth on the inside diameter of the drive wheel that line up with a gear on the axle. These teeth can wear out, especially if they are made of plastic. Higher-end mowers may feature drive wheels with a metal gear that meets the metal axle gear, which improves longevity of these components.

My lawnmower says I don’t ever have to change the oil, but just add oil when needed. Is this OK?

It’s not a good idea to never change the oil in your lawn mower. In a lawn mower, same as a car, oil degrades over time and is less effective at reducing heat and friction in metal components. Changing the oil in your lawn mower is easy to do and will significantly increase its service life. For most homeowners, changing the oil at the beginning or end of each mowing season should be sufficient, though there is certainly no harm in doing it more often.

Roy Berendsohn has worked for more than 25 years at Popular Mechanics, where he has written on carpentry, masonry, painting, plumbing, electrical, woodworking, blacksmithing, welding, lawn care, chainsaw use, and outdoor power equipment. When he’s not working on his own house, he volunteers with Sovereign Grace Church doing home repair for families in rural, suburban and urban locations throughout central and southern New Jersey.

Sources:

https://nelsontractorco.com/fix-hydrostatic-transmission-problems/
https://nelsontractorco.com/fix-hydrostatic-transmission-problems/
https://www.yourepair.com/1857/how-to-know-when-your-riding-lawn-mower-is-past-repairing.html
https://www.instructables.com/How-to-make-a-racing-lawn-mower/?amp_page=true
https://www.popularmechanics.com/home/lawn-garden/a27103287/self-propelled-lawn-mowers/

Lawn Mowers gearbox, lawn, mower, riding, your