Motorcycles, Snowmobiles, Go-Carts, ATV's and Golf Carts - go-cart/dune buggy crossbreed

Hey Mike!


I have a go-cart (sort of) question for ya! I am working up some plans to build a cross breed of go-cart and dune buggy. I want to make a cart that is bigger than a go-cart, smaller than a dune buggy, and faster than either :D :D!

I plan to use a honda 2 cyl inline engine...water cooled. I also want to use a transaxle, with reverse. My question for you is...do you know of a transaxle found in the lawn tractor application, that would hold up to high input shaft RPM, is synchronized, and can take a little abuse? I like the spicer 6 speed, but I think it's too weak. I would replace all bushings with needle bearings, and seal the case for the use of gear oil instead of the "00" grease normally used. I think the thin cases on these newer units will not hold up to the torque I plan to put through it. There won't be much lateral stress on the case and axles, as there will be a carrier bearing right at the transaxle for the axle, and then one out at each wheel. The axles will be extended a little, and probably motorcycle disc brakes on each rear axle.

You seem to know a lot about tricking up the little 5hp briggs engines, so I figure you might be one who would know a little about this kind of thing. I bet someone who races mowers could at least say what not to use, lol.

Anyones thoughts are welcome!

Godd morning cheese, well, I gotta tell you that adapting a transaxle for extreme use is not something I have much experience with. When faced with a need for speed on a heavy machine I go with a Comet torque convertor or Horstman clutch and live axle setup. The Comet torque convertor is a cop out opposed to your idea but is cheap, works well and is durable. Remember the Honda Odyssey?.....It had a version of a belt driven clutch and that thing was HEAVY and had a 250cc two cycle though no reverse. I have a friend that can make anything move including tugs, trawlers, dozers and anything else that must move from here to there and I'll get with him today and pick his brain.

I don't know what top end would be on this thing with high RPM input or if high RPM input is possible with a hydro pump but have look at this unit.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2059741058&rd=1

I'll get back on this......Mike

I really don't know how a hydro would do at high speed. I'm sure it would probably heat up pretty badly, but I could add a cooler. It's a thought. I thought about using the comet clutch and a differential, but I really want reverse. When playing around with this thing in the woods, I don't want to have to get out and push it backwards if I get into a place that I can't just turn out of.

Im interested to hear what your friend has to say!

I'm told the hydro thing won't work out because the pump pressure will only be so much regardless of input speed. Also, the standard transaxles would work with regard to the input speed and that makes sense to me because they aren't turning many RPMs in standard use. My friend did say he would open it up and clean out the grease, make sure all is sealed as you said and run STP or heavy oil in it. He feared the gear grease would get hot and settle in the bottom. I seem to remember at some point Murray used an axle that was 5-6 speed with 1 inch axles. That would really be a good starting point for this project....Mike

The things that worry me about the regular transaxles are:

1: the case is pretty thin, and I wonder if it would break where the input shaft comes out of it due to the fast accelerating and takeoffs.

2: the input RPM is normally somewhere, I guess, around 1000 RPM on many mowers. I know it differs, but they are geared down by pulley diameters to somewhere around 1/3rd of the engine RPM. I will be gearing it up to at least 1 to 1 ratio, most likely even faster, so the whole thing will be turning 3 or more times faster than it was designed to. I'd like to be able to hit at least 60mph. I'm probably too chicken to go much faster, lol!

3: the gears are made to withstand leisurely paced lawn mowing, at constant speeds. They will be subjected to constant hard accelleration and decelleration and shifting. I wonder if it can hold up to this treatment.

I bet someone knows which units will take this treatment, and which ones won't. A bigger unit like you mentioned with the 1" axles would definitely be the place to start. I can get these things dirt cheap, so I guess I could go by trial and error. It would be nice if I could avoid the guesswork though. I didn't even think of using STP. I bet that would be better than gear oil.

I've been thinking about trying to find a really old mower with a good, heavy transaxle, but I don't remember any of them being synchronized. Trying to make one synchronized would probably be more of a challenge than I want, LOL.

I probably won't have time to actually start building until a month or two from now, but I'm trying to get the basic materials on hand. I'll keep you up on my progress, if you're interested. :)

anyone out there into lawnmower racing or pulling?

Hi Marturo!

You don't happen to know what model the Peerless is do you? I don't know of one like you mentioned in production now. I do know there was one on some older riders though...I think I have a good used one, maybe two. They are 3 speeds with aluminum cases and cast iron axle housings. I hope they are the same ones that your son reccomends. If so, I won't have to look very far, lol. I aquired a tranny off of a John deere this evening. I didn't look at it long, and don't know who made it. I think it is a 6 speed. The case is all aluminum, but it looks sturdy and thick.

I'm going to check the 3 speeds to see who made them. Maybe they will be just what I need...although I don't remember them being synchronized.

All right!! :)

Do these trannies shift on the go? Or must you come to a stop to shift gears on these? I started putting things together a little bit this evening. I switched to a 14hp kawasaki engine as a power source. It's much lighter, easier to install, smaller, and virtually indestructable. The machine is starting to take shape!

Since this is my first go-round trying to get high speed out of a large engine and transaxle setup, can you recommend a drive-ratio for pulley diameters? I was thinking of making it 1:1 ratio, but that may not be enough.

What kind of setup do you use for brakes? That's one of my next challenges. I wouldn't think the small disc brake on the transaxle would be enough. The only thing I can come up with is small discs off of a motorcycle, adapted to the transaxle axles. This will involve a bit of work, so if you know of something better, I'm all ears.

Thanks for your replies!

Thanks to Marturo & Zac and my friend Larry we will get to the bottom of which trans is right for your project. Larry told me that most if not all transaxles that are syncronized are only clutched a bit to shift while on the move. When one moves the shift lever in and up/out or whatever all that happens is it releases a bit of tension on the belt a bit allowing a shift. I have been shifting riders with the clutch and the brake on the same pedal for years by pushing on the pedal slightly to relieve tension but not getting to the brakes with no problems.....Mike

Thanks everyone!

Marturo...This is a live axle/differential setup, rather than a straight fixed axle. Interestingly, I contemplated using a kawasaki 2 stroke 250cc motorcycle engine. I figured that was a bit of overkill, lol. (a tiny bit) :D

I know a guy who used almost the same engine on a cart and said he was too scared to drive it. He said it would go from 0 to 60 in about 200 feet. YIKES! If the tires didn't spin so badly, I wonder how much shorter the distance would have been.

I plan to clutch the belt with a tensioner pulley. I found the gear ratio of 3rd gear in the tranny to be about 13:1. At 3600rpm engine speed, 18X9.50-8 tires, and a 1:1 pulley ratio, and 13:1 gear ratio, I calculated only about 16mph. So I guess I will have to go with a larger drive pulley, like you said.

Mike...As far as I can tell witout going into the unit, this one is not synchronized. Hopefully I will be able to do what your friend and Zac said and clutch it lightly, possibly while trying to match the rpms a little, to get it to shift.

I may have found the secret to the braking system today. Later model small cars with 4-wheel disc brakes have a small drum inside the rear discs. There are small shoes designed to be the emergency/park brake. I could machine the rotor off of the drum, and use the small brakes which are conveniently cable operated. The main thing would be constructing a backing plate for the brake shoes and hardware. I don't think this would be too hard, and should be quite substantial for this lightweight machine....I hope.

I'm sure I'll run into more obstacles along the way, but for now, I think I'm satisfied with the plan you guys have helped me with. Thanks, and I'll be back...I'm sure! :)

Ok....update time! :)

I have the frame pretty much together, the steering is all completed, and I am getting the engine and tranny positioned to mount. I went with 3:1 pulley ratio after figuring what it would take to get the desired speed considering tranny ratio, engine RPM, and tire size.

Zac...I couldn't find any manufacturers' mark on the tranny, and since it is so old that I'm not familiar with it, I took it to a friend who has been in the business much longer than I. He said the unit is made by Foote. I suppose this is not the same one you reccomended? It IS a 3 speed w/reverse, I-pattern shift, cast iron axle housings, 3/4" axles, 1/2" keyed input shaft. I was told it is a heavy-duty unit though, and used in the 1970s. Could we still be talking about the same trannies?

The only numbers or markings of any kind that I can find are cast into the aluminum housing, behind the park-brake disc, and they read 2492-PI . The brake disc has to be removed to see the numbers.

I also found out that this unit was used on old Dynamark (noma) mowers, and old Murrays. I don't know if it was used on any others or not.

I'm using a 110 volt, 80 amp flux core wire welder to put this frame together. Ever used one of these? It is really hard to get a pretty weld out of it...for me anyway. Looks like it bonds well, but I have to grind down the lumps before anyone comes in and sees it, lol!

Thanks!

By the way...You mentioned the mods I was planning to make to the tranny? Well, I started to take it apart only to find that the case is already gasket-sealed, it doesn't use grease, it uses gear oil, and it has needle bearings instead of bushings. It even has oil seals at every shaft. I guess I don't have to do much of anything other than changing the oil (which is clean) and the axle seals. It doesn't feel like there is too much internal play either. That just shaved some time off!!

Hey Marturo...Just FYI...I changed the brand of wire I was using in the machine, and the welds look great! Now I can go easy on the angle grinder, lol! That little welder sure is a handy machine to have (now that it's working well). Know what's funny? : the wire that didn't work well was twice the price of the wire that did. Just goes to show that price doesn't always reflect quality.

Cheese