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Starter, Shims and Flywheel Issue


BiggyJ

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Hello everyone...
A little help would be greatly appreciated.
I have a 92 Sierra 1/2 ton. It has a 350 Goodwrench crate engine in it. I took some pictures of the block and head numbers when I got the truck but lost them in a hard drive crash.
Best I can remember the block had a mid 80"s casting and the heads had a late 70"s casting.
My problem is that I had to replace the starter and I order everything online to save money. I chose a starter from an 87 Suburban with a 350 and ordered the starter. I did not think to check every tiny measurement while I had the core at the auto parts store (ship to store). In this case I would like to have checked out the pinion travel distance. I know the 80 year model had the same bolt-on pattern but it was a different part number so SOMETHING was different.
After putting it on, the pinion stop collar is really, really close to the flywheel.
I have uploaded two pictures of the starter and the flywheel area and an mp3 file of it starting. Something is just not right.
There is ONE area (about 6 teeth on the flywheel) where you can see where the old starter did some damage. 99% of the time it will start ok but it sounds like the pinion gear is not releasing immediately and there is a small grinding type sound at the end of the cranking cycle. There was ONE time where the pinion gear did not lock into the teeth on the flywheel and I just got that grinding noise. We've all heard it. Starter pinion tries to engage but just grinds trying to get into the flywheel teeth.
There was no shims on the starter when I took it off so I tried to widen the distance between the pinion collar and where the pinion should mesh with the flywheel. Can that be the problem"
Here's the other thing, the kids put the newer style tranny in it. What is it? The 700R4, I think. So I am wondering if there is a compatibility issue there?
Anyway, I did the best I could taking a couple of pics but the exhaust system was sort of in the way.
Can you experts please take a look at the pics and listen to the short MP3 and let me know what you think?
Thank you very much,
John

 

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OK guys... thnks alot. I shimmed her up and it sounds right except for a bit of a spin after I disengage the starter. Guess I can live with that :)

 

Thanks a ton,

John

 

 

PS - Is the spinning noise usually a sign of a bit too much or too little shimming?

 

Depends on the sound. A little spin is normal, as the starter has to retract, and the rotating mass has to wind down. But if it's spooling up too fast due to the engine starting before it retracts fully, that could be a starter bendix issue, or it's still shimmed too tight.

 

So long as that 1/8" drill bit fits with slight drag between the starter's pinion shaft and ring gear, it'll be fine. If you have to force it in there to fit, then it needs to come out a few thousandths more.

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Agree with Jsdirt. The noise you hear at the very end of the starter disengaging is due to not enough clearance between the drive and ring gear. If the pic that shows some minor damage to one edge of about 6 teeth is ok, not enough damage to hurt anything. Once you get near half a tooth missing it will begin make noises sometimes, and not engage the starter sometimes. Used to be we would repair the starters in house, that meant never having to worry about the shimming. I got out just as exchange parts become popular. Got lucky I guess, only had to change one shim adjustment, and that was on a buddy's race car. It was also before gear reduction starters appeared and having high compression hot engines required the best starters money could rent.

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On the Dodge gear reduction starters of old, when the stater would "run on" after engine start we would pull the starter and replace/install a leather washer behind the gear reduction gear. That would put enough of a preload on the shaft to stop it from spinning as soon as the bendix was released. Don't know what they are doing with the gear reduction starters on new vehicles though. Used to be only Chrysler had the gear reduction starter motors. The starter drive pinion gear has a type of over-running clutch on it. This will allow the engine to start up without driving the starting motor speed skyward on ignition. Starter will not last long if the drive is no longer free wheeling in one direction. The engine can spin the starter up to a speed that can cause the armature to come apart. Also, I have seen one instance where the over running clutch was still working, kind of, but the free spinning part was almost like it would spin freely backwards, and this would let the engine spin the pinion gear itself on startup, causing it to sound like the starter was still driving, when it was just the pinion gear freewheeling due to over running clutch starting to fail. You could take the pinion gear and spin it forwards freely. There is normally a drag on the pinion gear when you engage the over running clutch.

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OK guys... thnks alot. I shimmed her up and it sounds right except for a bit of a spin after I disengage the starter. Guess I can live with that :)

 

Thanks a ton,

John

 

 

PS - Is the spinning noise usually a sign of a bit too much or too little shimming?

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You need to shim the starter. Get a 1/8" thick drill bit, and place it between the pinion and the flywheel when the bolts are tight - if it's too close, you'll need to shim it out. In that case you can shim just where one bolt goes in to swing it outward a bit. That 1/8" bit should fit perfectly in there with no slop, and no forcing it in.

 

Every time you get a different starter for these, you usually have to shim them, unless you get super lucky.

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