Gen. Mayhem- Racing Tractor

[Doc Sprocket]

I certainly could. But after selecting the ratios that I did, I concluded that another gearset was pointless.

If you look at the picture, Immediately to the right of the far right gearset- on both shafts is a collar. I would remove those collars to make room for another gearset.

 

[DaiSan76]

You said this was going to run 18hp?

 

[Doc Sprocket]

You said this was going to run 18hp?

Yessir, I did!

I just had me a wee epiphany! A little background...

I have removed the reverse chain from this tranny, because the rules allow for it, and it eliminates a major potential for failure. As a result, shifting into reverse results in, well- nothing. It's a second neutral, really. But I wasn't happy about having that second, ghost neutral position. I'm building a racer- I do NOT want any ambiguity or guesswork while driving.

I examined the tranny, and started hunting for a washer to install, to stop the shift keys from indexing with the reverse driven sprocket. Mid-hunt...

All I had to do was to remove, flip, and reinstall the sprocket... That dang simple. The index slots for the shift keys are not cut completely through the sprocket. Having the sprocket installed backward gives no place for the shift keys to go. Therefore, problem solved! N-1-2-3-4, and nuthin' else. Sweet! I love free, effortless solutions!

The sprocket is offset, so it no longer lines up with the drive sprocket. No chain, no issue. There is no interference either.

And no, my phone does not take good macro shots... If you CAN make it out, first pic shows the sprocket installed correctly, with the shift keys adjacent to the slots. Second pic shows sprocket reversed, shift keys have nowhere to go.

 

[devilstear]

this is nice,i always had an image pop in my head about these mowers racing every time i saw one,just never really knew they actually have races for these,it must be pretty fun, nice work by the way

 

[souperman000]

How does the shift key work? Is it just the key stock?

 

[Doc Sprocket]

How does the shift key work? Is it just the key stock?

Well, basically. The shaft has two keyways, at 180* apart. Some models actually have four, at 90*. The shift keys (will provide pic later) slide along the shaft, and index with the various gears, including (normally) the reverse sprocket. The keys are held in the shift collar, which is actuated by the shift fork. The shift fork is connected to your hand.

 

[Doc Sprocket]

Got a fairly mild day here, and cleared a bit of room in the garage. Got my kerosene heater keeping me from freezing my junk (and my stuff, LOL), so I figured I'd plug away at this a little more.

My 18hp Briggs Oppy came to me ungoverned, and the rules don't allow for that. I had made some trade action happen maybe a month ago for a 16hp donor engine. So I just finished installing the missing external linkages and setting up the static adjustments. Fortunately, my internals were intact.

I have also yanked my flywheel, so I could remove the alternator. I also compared cylinder heads between the two engines, and they appear the same. I was actually hoping the 16hp head had a smaller combustion chamber so I could up my compression a wee bit. Oh well.

While at it, I've installed the fuel system. From the tank, I have a filter, primer bulb and shutoff valve before it gets to the pump. The tank sits lower than the carb, which is okay because these engines have a factory diaphragm pump on the carb. I added a marine primer bulb to get the line primed in the first place.

Well... Back at 'er!

 

[Doc Sprocket]

I got a fair bit done today. I-

*Finished rebuilding the header/collector and got it mounted, including the support bracket.
*Altered the RHS running board to clear the header
*Dropped the hood 1" in the rear, and 2 1/2" in front to give it a gentle rake
*Got tired of staring at that huge cutout in the hood, and mocked up some bodywork to fill it in. Got lotsa room for lettering, numbers, sponsors (LMAO) etc.
*Made it into a tilt frontend- whole hood and grille shell now flip forward for slick easy access to engine and fuel tank.
*Steering wheel boss is now mounted to the column, and so is pitman arm.

I also tore into the carb- sorta. I wanted to compare jet size with the 16hp parts engine carb I got. The jet came out of the parts carb easily enough- it's a hex socket head, unlike the flat (slot) jets we see in Hondas, clones, etc. However- the jet in my 18hp carb was stripped!!! Aww, F!!!

Much screaming, and the right extractor later, I got it out. The first thing I did was file a couple slots in it, so I could install and remove it with a flathead screwdriver.

Interestingly enough, it was the exact same jet for the 18hp, as for the 16hp... Who knew?

 

[Amped]

Its gonna be "Badasks" as Popeye would say.
Looks like a fun profect.

 

[landuse]

Interesting gear selector.

Are you going to actually race the mower when you are done, or are you just building it to racing spec?

 

[Doc Sprocket]

Interesting gear selector.

Are you going to actually race the mower when you are done, or are you just building it to racing spec?

Good question. My initial self-induced challenge was simply to build one to race spec. I figured it would be an interesting challenge. Let's face it- I could have done it up a bit, slapped maybe my XR100 engine on it, and had some fun. However- I kinda saw a "roots-of-autoracing" thing, and started scouting clubs and downloading rule books. My end game was to finish it, and get it certified by a race tech. From there, I'd probably just have some laughs with it*n then sell it.

The biggest hurdle I face, is that the closest mower race organizations are 3-4 hours' drive away. I might be willing to do it for a tech inspection, but that's a LOT of drive time for a full season of racing. So, I am desperately trying to find a club closer to home, but no luck yet... We'll see.

 

[Doc Sprocket]

Freshly demagnetized flywheel, shown next to my original 'wheel- kept stock for obvious reasons! Those magnets are a real pain to get off until you figure out the trick!

...By the way- did you know that superheating a ceramic magnet with a torch causes it to explode? Neither did I, 'til tonight!

 

[machinist@large]

...By the way- did you know that superheating a ceramic magnet with a torch causes it to explode? Neither did I, 'til tonight!

I sure hope you did that in a really well ventilated area.... Rare earth/ ceramic magnets are made from some really toxic ingredients. There used to be a Hitachi magnetics plant in my region of the State; we used to build/ rebuild tooling for them. They wouldn't tell us just what was in the powder that the rebuild stuff was covered with; just Do Not Breath It, and if it caught fire, RUN!!!!

The cover story for them shutting down the plant was oversea's competition; the real reason was that it was going to actually cost them some money to bring the plant into compliance for enviro./ plant safety. They never upgraded the plant's safety spec's when they changed over from the old style magnets to the rare earth/ ceramics....

 

[Amped]

Freshly demagnetized flywheel, shown next to my original 'wheel- kept stock for obvious reasons! Those magnets are a real pain to get off until you figure out the trick!

...By the way- did you know that superheating a ceramic magnet with a torch causes it to explode? Neither did I, 'til tonight!

I wish you had caught that on video.

 

[Doc Sprocket]

If by "really well ventilated area", you mean, "in my garage with the door closed", then- YES! LOL... Actually, I only had the heat on one magnet for a few seconds. Once it started literally shooting chunks into my face, I shut the torch off, figuring I'd better come up with a new plan...

 

[Pocketrocket]

Hmm i don't think i'd be doing it to racing standards i'm thinking something more like this http://www.youtube.com/watch?v=SzpLw15UfFg&feature=related

 

[Doc Sprocket]

Yeah... That'll happen on this budget.:toetap05:

I'll be bringing this in well under the $500 mark. Probably $350-$400.

 

[matoolis]

Hmm i don't think i'd be doing it to racing standards i'm thinking something more like this http://www.youtube.com/watch?v=SzpLw15UfFg&feature=related

That thing is sick!! any idea what motor is in it? i'd love to see that setup...Toystory, your build is turning out awesome, can't wait to see it finished!

 

[machinist@large]

TS, I agree with matoolis about your McBudget project; Very Cool!!

That being said, if anyone knows what the tractor in the video has for an engine, I'd be curios to know, as well.

 

[Amped]

TS, I agree with matoolis about your McBudget project; Very Cool!!

That being said, if anyone knows what the tractor in the video has for an engine, I'd be curios to know, as well.

zzr600 Kawasaki?