09 drive clutch noises

[dbmachine]

THis cart has a jakes lift and 23" tires. When I purchased the cart, the speeds were slow so i cranked down on the 10mm nut. Good speed but very poor acceleration and jerky while taking off. I purchased a new erlandson severe duty belt and also a speed spring from ccp. After i installed the new belt i took the cart for a test ride. Had alot better acceleration and better top speed than before but started making a rattling noise only when wide open with the gas pedal whether going forward or reverse driving down the road.

Did some trouble shooting as to what the noise could be. If i put the cart in neutral and go wide open with the pedal there is no rattling noises. I put the cart on jackstands to let the tires spin freely and then wide open throttle in forward and reverse and it doesnt make the noises. I then installed the speed spring and went for a test ride. Same rattling noise at wide open throttle while driving down the road. Im stumped as to what it could be. I would put the trashed oem belt back on but it is trashed and is comming apart and besides i caught hell trying to spin the new wider and shorter severe duty belt onto the secondary.

You guys have any suggestions?? only changes were a new belt.the new belt will now ride all the way to the tops of the sheeves at wide open throttle unlike the trashed oem belt..thanks