Starter shimming.

[hopped up]

My 64 c10 with 350/350 combo is showing all the signs of me needing to shim my starter. I've had several old chevys and have heard many people having to shim starters ,but I've never had to. So my question is how thick of a shim should I start with? Or what's a good way to figure out what size shim I should put? Thanks

[A.T. RockDriller]

Good day, Hopped up,

I was a Mr. Goodwrench tech for a while in the old days.
You may already know this, but I'll run it by you anyway, Just in case.
If your starter and flex-plate/flywheel have been on your truck and worked properly for a while.......and then, all of a sudden, somethin aint right and you don't engage right and it grinds and spins and whatever.....

Well if it worked right and now it doesn't, shimming wont be the complete answer.
Shims are used to set the initial tolerances between the ring gear and the starter abendix/drive gear on initial assembly or installation of your starter. There should be no instance where any sort of wear would require shimming to correct it.
However.....you may need a new ring gear....and/or starter drive gear.
A lot of times the starter solenoid will get weak and not stroke completely....thus not engage deeply enough into the ring gear....thus grind like a mutha.
Other times the starter mounting bolts will loosen or the end housing will crack....causing a misalignment of the starter.....again, grinding like a mother.
Take it apart and look it over closely.
I'm sure you'll see the problem. Get a good angle so you can see the condition of the ring gear...too.

Good luck.

[awbrown]

If I remember right the factory spec for tooth engagement it .030 valley to peak clearance.. with starter drive engaged,(solinoid off the starter ) a round .030 wire (paper clip or whatever thing you can find close to that ) should be able to be slid between the top of the tooth and the flywheel ...........

[Heater63]

AW has it right. Shim using a paper clip as your clearance tool between teeth and flywheel and you should be fine.

[A.T. RockDriller]

The point I'm trying to make is that if your tolerances were correct when you first installed the starter.............and now it all of a sudden " needs shimming ", then your problem is a bit bigger than a paper clip.
Maybe I misunderstood the original post.

[NorthstarGMC]

AT is right, if you're shimming an existing install, something else is wrong and this re-shim will hid the problem for a little bit maybe but it will bit you in the ass later.

If you've just put a new starter or flywheel in and are setting initial backlash then you can shim.