Shimming Comet Driven Clutch Spring

[sharse36]

On my 1987 ezgo Marathon, I'm looking at shimming my Driven clutch spring. My cart up shifts to fast and bogs down. Has a new comet drive clutch and belt. I have a Comet Driven clutch that is about 15 years old. I believe the spring is getting weak. It is really bad on hills until you stop then you can make it.

How big of shim can put in it 1/4", 1/2", or 3/4" ? I have a friend that can cut the shim out for me with a laser so I can make it to the right size and thickness.

Any ideas how big to go to make it better with out buying a new spring or clutch.