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Step 12Updates 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.
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.
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.
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.
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