Originally posted by whynot
When it is on the starter box and you are reving it up can you feel if it is shifting into 2nd gear and does your motor sound tuned nice and crisp? If it does than it is your clutch when the weight of the car is against the clutch it is making it slip so when you are at a low rpm it is prob. grabing a little but when the motor really starts to sing a high rpm it isnt grabing the clutch bell enough.You need to add some shims so that your end play is just a little bit not real sloppy prob. about .3-.4 mm of end play and when you get that set you need to make sure that your clutch nut isnt to loose also if it isnt tight enough it can bog the motor down. so you prob. want the clutch to kick it atabout 1/4 of throttle but that is a personal preferance. Hope this helps.
Yea i think this is probably the problem. It almost feels as if the clutch isn't grabbing, but why would it only do this after a few seconds of running? I don't quite understand what you mean by adding shims though. I'm still fairly new to nitro's so a lot of the refferences you made I'm not to sure about.