Originally Posted by
bjr48
I know of a couple of different ways to tell if the piston/sleeve is very worn. How do you determine if it's "mostly" worn and should be pinched to avoid running it until the very end?
I use several methods. First off, I pay attention to how easily the motor spins over on the starter box. Then, about once a race day, I try turning the motor over in the car after it is hot. You will soon get a feel for compression on a hot motor.
Each brand of motor will have a different amount of pinch. For example, older OS and Nova-based motors have a lot of pinch. V-spec and Sportwerks motors run well with minimal pinch.
The ten-second test is a good one to use when the motor is out for servicing the clutch. The last test I do is to push the piston up into the sleeve before getting it re-sized.