When the distance between the starting gear and the flywheel is too tight. I had to put them in my Corsica as the gear was too tight against the flywheel, when it spun out causing the gear to not retract right away. Also used to change the mounting angle of the starter to adjust where the gear lines up.
[This message has been edited by jaskispyder (edited 02-07-2013).]
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08:39 AM
Gall757 Member
Posts: 10938 From: Holland, MI Registered: Jun 2010
The axis of the flywheel and the axis of the starter shaft have to be 'just right' in order for the starter gear to engage the flywheel gear without binding. There is a stack-up of tolerances in all the parts involved, so the design engineers knew there would be a problem with some installations. The remedy was to design the assembly so the gears would interfere with each other, and add shims when needed to make them move apart just enough to free up the starter mechanism. You have to add shims if, when you crank the starter, it sounds like your battery is low, but you know it is not.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
EDIT: old starters have to be shimmed, not new ones...???
Yes and no.... They usually tell you to use the same number/size of shims if you replace a starter. But of course, you should check it each time. I don't mess with it. If the new starter functions, I just let it go with what was there (shims or no shims). I had to only adjust shims once over the course of multiple starter changes as the previous mechanic didn't have the correct size in there.
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10:03 AM
AL87 Member
Posts: 2578 From: Bradenton, Florida, United States Registered: Mar 2010
Originally posted by AL87: 1. so... do all starters have to be shimmed then? 2. EDIT: old starters have to be shimmed, not new ones...???
1. Most 2. No. Many replacement often use same shim IF flywheel isn't replace etc.
Starting point use old shim came on engine in question when Flywheel is same. (Assuming replacement Do Not say No Shim in directions or stamped/printed on starter itself.) Always use a gauge to test clearance.
Shimming is to address "Tolerance stacking" (Google that...) Starter, engine, flywheel as have +/- tolerance. Some all are on plus, all minus, others are a mix.
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Originally posted by jaskispyder: BTW, shimming the starter with the engine in the car.... not so fun with the auto tranny It is guess work
Yes. GM method is a nightmare. A little easier use aftermarket method. Make sure you don't hit housing/flywheel... Only area goes between starter and flywheel makes any contact.
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Originally posted by Stainless1911: The TRY HERE button on your link doesn't work, gives a 404. At the bottom, under Starter Upgrade.
I fixed that... Future ref, Just click PFF says "However, I found this thread:" link... PFF just Archives threads when no post in X weeks/months.
[This message has been edited by theogre (edited 02-07-2013).]
It is guess work 
