I'm replacing the starter in the '89 Iroc with manual trans. This should be a 10 minute job, but is turning into a nightmare. The new one from NAPA makes a horrible grinding/ clashing sound like the pinion teeth on the starter aren't meshing properly with the flywheel. To get the proper clearance I used a .020" shim. I also tried everything from no shims to .064" shims but continue to get this same horrible gear clashing type sound. I'm about to try a different rebuilt starter. Any other suggestions?

 

I would try getting a new one, there is a slight chance that you chipped a tooth off of the fly wheel and it lodged it self some where but that seems unlikely. How are the teeth on the starter that you just put in? Also are you shure you had it shimmed properly? That is very, very imporants becuase you will start to loose those teeth if you don't. Good luck, otherwise you can put the starter up on the bench and connect it directly to a 12V power sorce to see if its inside the starter. That will atleast tell you if its the starter or something else. Goodluck!