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How to make a racing lawn mower (Updated!)

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Step 3: Steering system

Picture of Steering system
steering_bearing_holders.jpg
installed_steering_axle.jpg
pitman_arm_detail.jpg
steering_arm(2).jpg
turn_right.jpg
removeable_axle_top.jpg
after_new_stops.jpg
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!
 
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jeff0917963 years ago
would the front axle work on a sears lt 11/36, this is a huge riding mower, my steering linkage from the gear to the spindle broke, and they don't make it anymore, thanks jeff
mowerracer (author)  jeff0917963 years ago
It should work with that Sears mower just fine. The thing to remember is that the stock steering systems on these mowers are pretty much useless. The geared system you mentioned is notorious for breaking and slipping if used for anything other than mowing. The idea is to create what's known as a "direct" steering system. In other words- positive linkage from the steering wheel to the spindles. There are a number of front axle manufactures like Acme as well as some from a company called EX motorsports. They should have the neccesary hardware to enable you to make a direct steering system. Check out www.heymow.com and look at some of the project builds to get an idea of how to make your steering system work. There are some good ideas there.
Ken Chevy3 years ago
  Hi, In Step 3 you say:
  "Generally, it is better to have the left wheel turn in more than the left."
  Should the last word be 'right'?

  Nice Instructable.

  Ken Chevy

080810 1320
mowerracer (author)  Ken Chevy3 years ago
Yes... Sorry about the typo.
  I guess I missed something or don't understand something about instructables.  I have never made an instructable, but are you saying a person can NOT go in and correct errors?

   I would have thought the owner of the instructable could correct errors? 
 
  A person should always correct errors if possible so people reading the instructable  doesn't get frustrated because they can't figure something out because something was entered wrong.  You correct your mistakes so people understand what you have written.

  Like I said above, you have a nice instructable, well written.

  Regards,

Ken

080910 0829 
miketryiu4 years ago
 wow wheels... how to you have wheels new? 
hockeyteen64 years ago
I have a true test riding lawn mower and I need to know how to transfer the power from the cutter to the wheels. thank you.
mowerracer (author)  hockeyteen64 years ago
Well on most riding mowers there is a single engine pulley with two belts- one for the deck and the other for the transmission. The mower deck will have nothing to do with getting power to the wheels at all. power will come from the transmission. Lastly, just because this needs to be clear, the mower blades must be removed if the mower is going to be used to go faster than stock.
thank you
MikeJohnson5 years ago
i got a racing lawnmower and i need a different steering system as the one that i designed isn't to hot. i ve been thinkin of ur set-up and think im goin try it. do u now if it will work all right on a heavier mower? im also wondering about the pitman arm coming from the wheel, can u tell me everything u did for it? angle? ofset?......... Thanks Mike
fast-dude5 years ago
so did it come with everything you needed to have it go over the engine?
mowerracer (author)  fast-dude5 years ago
No, I had to fabricate the steering connecting rods, pittman arm, and the hubs that house the bearings for the shaft that goes down the front of the mower frame to the axle. The hubs are made from pieces of 1/5/8" steel pipe cut into small pieces. The bearings are from a hardware store. The steel rods are just raw steel rod stock, and the heim joints ( ball socket joints) are welded to the ends of the pieces so they can swivel. Making the steering system is probably the most difficult part of the build and expect to have a lot of trial and error. Handling is everything, much more so than speed and power. So get it right the first time and you'll be ahead already.
fast-dude5 years ago
what hook up for the steering did you choose?
mowerracer (author)  fast-dude5 years ago
This is a center steer setup. The steering arm goes over the top of the engine, down the front, and to the front center. This is actually how the mower came, so I just stuck with that system. On other builds, people will run the steering shaft UNDER the frame with a pitman arm attached underneath for the steering arm which runs to the right side typically. Check the Acme mower web site because he has both setups as well as some diagrams for setting them up.
the front axle....is that the center steer from the website you have listed? how much?
mowerracer (author)  railroader0101715 years ago
The front Axle is indeed an Acme Center steer unit. They run around $120, which is reasonable since if you made it yourself, you'd be saving maybe $30. I've used two of these and they work great.
Merkatroyd5 years ago
What size wheels did you use? Where did you get them?
mowerracer (author)  Merkatroyd5 years ago
These are actually Go-Cart tires and rims. The rims are 6". The tires makes them around 10-12". I can't recall off the top of my head. I bought them from a place called Turk Brothers racing. They have an online catalog. I have to say that they're kind of pricey, as in $30 for each rim and $50 for each tire.You'll also need the hubs for them. Many people just use the stock front rims,punch out the original hubs and install cup bearings. They're a standard size, so typical bearings found in hardware stores/dollies fit great. The rears can be either the stock original or golf cart tires work pretty well too, but you will need a 4 on 4 bolt pattern hub to fit these.
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