Jackshaft or torque converter?

[jamilcobra]

Hello. I need some advice on a torque converter. My kart is set up with a 10 tooth arena clutch with a 70 sprocket. It is used in parades so its wide open for 30 yards or so then hit the brakes, turn and repeat. The 7.0 gear is perfect for what we do, but it is hard on equipment. I generally get about 3 or 4 runs before the clutch bearing needs to be replaced, and the clutch hangs off the crankshaft which is surely putting extra stress on the crank. With this in mind I am trying to decide between a jackshaft or torque converter. I understand how each works, but I am curious about the durabilty of a torque converter. Can it handle constant starts over and over, and will it pull as hard as a cetrifugal clutch? Also will the belt take the abuse? The engine is a stock yellow clone with a bored carb, no governor. Just guessing but it is probablly turning around 4000max during parades. Thanks guys.

 

[Doc Sprocket]

I have no doubt the CVT will tolerate the "abuse", but then- I can't understand why your clutch won't take it. 7:1 should be deep enough for the purpose. Are you oiling the clutch bushing properly, and maybe your chain is too tight? Should be some slack there.

 

[jamilcobra]

Well, the frame is an old rupp dart kart modified to hold the body. It is around 40 to 50 years old. We run a hard compound race slick, and make 180 degree turns on asphalt, so I would imagine the frame is flexing a fair amount. The clutch itself does not slide all tthe way over the crank. Starting at the sidecover there is a 1 inch spacer the inner hub with the shoes. The actual clutch drum hangs on a snout that sticks out of that hub. So the chain is three inches or so from the block. I keep the chain slack, but my guess would be that when the frame flexes the chain is tightening up and pulling on the clutch, which is magnified by the fact that its so far away. What I'm trying to say is that if the clutch were mounted inboard and the engine flexed a 1/16th of an inch, then the chains slack would accomodate it. Although since the clutch is outboard and so far away, then 1/16th of an inch would be multiplied like a lever. I am going to change it out, and either go with an inboard mounted clutch and jackshaft or a torque converter.

 

[Doc Sprocket]

Given your very specific purpose, I think the centrifugal clutch is the right choice for you- once you get the alignment sorted out.

 

[jamilcobra]

Thats kinda what I was thinking. I am probablly gonna use a 13 tooth noram ge since it has a needle bearing hub. The larger bearing surface closer to the block should eliminate any binding, and the jackshaft would leave plenty of adjustment for gear ratios. I just really want a reason to put a tc on it and see how it would drive with the variable ratio.