1997 GMC 3500 grinding starter have replaced and shimed several the starter and fly wheel any sugestions would help
One way to narrow the problem is to wrap thin (16 gauge) solder around the starter Bendix gear; block the Bendix out; mount up the starter using the shims you have used; don’t connect the electrical; rotate the engine with the harmonic balancer bolt one turn; remove the starter; and check to see how much the solder is squished. I don’t know the exact mesh clearance required but if the solder is not squished or if the solder is completely flat or broken, you need to go with less or more shims respectively. Good luck and let us know what it took to solve this problem.
Had the same problem with A Chevy Caprice, due to a poor quality rebuilt starter. I ended up replacing both flywheel and starter, using a GM flywheel and a better quality rebuilt stater. My own mechanic could not fix the cheap one, and the installer would not take responsibility for poor work/part. You may be lucky and able to fix the alignment and meshingproblem.