Starter pinion gear??

[ranger350v]

What causes the pinion gear on a starter to get chewed up? My 2.4L, about every 2 years I have to replace the pinion gear because of this. The fly wheel has/shows no wear marks from the pinion gear. Do I need to shim the starter out some or just let it go because this is normal wear?

[WATERWINGS]

Mine does too.

I start mine in gear, and have high comp. heads, so thats what I figure is doing it, plus I have a light weight flywheel, (I think the teeth are thinner)