Tire size vs torque

jbuhr

I have a 88 par car that runs great on flat ground and small hills but I want to use it for hunting and it slows down alot on larger or long hills. It has a 5 in lift and 23 in tires, I was wondering how much of a difference it would make switching to 20 in tires or any other ideas beside big block that would help till I has the money for another motor

BGW

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TerryH

The smaller tires will certainly help with the torque issue but I'd guess they'd look a little odd with a 5" lift.

sho305

If they need it at all, clean and lube the clutches and try a new belt. It can make a lot of difference because if its not at peak rpm under load you will not get all the power you have. With 9hp in most stock carts you need it all, the clutches need to shift properly.

Sure smaller tire diameter will gear it down and help, but you lose top speed. I would guess it will help you more at low speeds and less at higher speeds.

jbuhr

Do you think it should pull steep hills with two guys in it with it being stock and having 23 in tires? I was thinking thy were a little big for not having any mods but maybe I'm wrong.

sho305

My 22s measure 23, my G9 crawls up steep hills. What can help is a cut secondary sheave it gives a lower gear. But that only helps under 5mph or so. I put a clone in a G9 and it blows me out of the water there is no comparison. I have a ditch over 6' deep and starting at the bottom I barely go up it. The clone with two people on it spins up it and lofts the front tires up in the air over the top. So yeah, putting a clone in my cart for sure lol.

Most lifted carts at under 5mph and high load (steep hill or towing) they bog the rpm drops, if that happens a cut sheave will help you. You will have a lower gear but still have same HP. But stock carts with little tires were never made to gear that low they didn't need to....lifted cart you do need it, with stock power.

Oh, and I rebuilt the clutches on a G9 and put a cut sheave on it. I drove it and noted the differences. Then I put a clone in that cart so the clone does have the cut sheave. You don't typically need it with larger engines because they have more power anyway, but it does help it spin up to rpm faster on take off and hills. Because it does use the stock yami clutch that engages pretty smoothly/slowly/etc.

jbuhr

so how exactly do you do this. sorry im new to the cart thing and just go this one cause it was free and already lifted with wheels and stereo so i couldnt pass it up

sho305

I think the par car was a copy of a yamaha G2 or something, not sure. I have no idea what clutches and such are on it, I can tell you clean and lubed they will usually work better. You can cut the sheave yourself, well not unless you are a machinist, but you can get it done. All they do is take the secondary clutch off the trans, then take the moving sheave iirc and cut the back side in the center. You get a new belt and the idea is to make them come closer together and push the belt out the top a little maybe 1/8 at rest. They touch in the center so you mill that down a little. Check the photos of yamaha cut sheaves where they sell them and you can see where they lathe them down a little. Make sure it will not fall off the ramps if you do it, etc, but you don't cut much off anyway only takes a little to push the belt up. Also make sure the engine is mounted solid and does not pull into the trans under torque, that will make it gutless climbing. Yamaha has a cable on the engine for that, some carts don't. Another thing is if the clutches are worn a lot they get dished in from the belt, then they don't shift right usually can't push the belt to top of one or both clutches, they have to be replaced. Eventually they wear holes through them and break. Also a new belt tends to work better as a worn belt sits lower in the clutches.

jbuhr

ok thanks alot i will try all of this thanks for the help

spriddle

You can also try a slight smaller/wider drive belt (not much). It will take away from speed but can help with climbing. But the best way to gain torgue is too beef up the rear clutch so it is harder to pull it down between the sheaves, keeping in mind your drive clutch is in good shape and operating correctly.