Shimming a starter

cajos1968

cajos1968

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Joined
May 13, 2008
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Leiden, The Netherlands
When I removed the starter the were a couple of shims. What is the purpose of these shims. I though when I removed them it is to get the sprocket distance to the fly wheel, but it moves it down wards?

Q2: My starter sprocket only comes halve way the fly wheel, is that correct? How can you fix this?
 
I can't swear when/how it happened, but I lost a flex plate to 1/2 the teeth missing from a spot....and so it finally went totaled.....

I noted there is a lot of slop in SBC starter mounts, I tend to use NO shims on my setup now, with a mini starter/high torque? thing....anyway, I noted when pulling the Bendix spring/clutch rearward to it's limits, that the starter can in fact be slid forward on the bolts, and have just enough engagement of the teeth to make troubles....so I make damn sure it's far back to rear of the car it can be, then tighten bolts....I dunno why, just is....for MY car....

I had to do that with the old starter also....'89 Truck roller block...
staggered mounts, as I recall.....

:stirpot:
 
cajos1968 said:
May be it's my crappy english. But what am I aiming for when shimming the starter?
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The shims control how tightly engaged the teeth are....>< so to keep out of the throat with the teeth....

I"m talking of how far down that 1/2" or so of bendix teeth, that flywheel rides...it certainly should ride the full depth of the fly/flex about 3/8 inch...not the way I mistakenly had it. so that thing actually engaged only 3/16 of the flex plate....that IMO, caused the flex to fail....


:friends:
 
cajos1968 said:
Okay, mine is halve way!! What is the fix?
Click to expand...

You mean only the front 3/16 of the fly teeth, 1/2 the length is not engaged with the starter bendix, and 1/2 ARE??

I would loosen the bolts, slide the starter to the rear far as possible and snug them down...and pull that bendix to rear of the car, and see....

if not, sometimes, I am told, the rebuilder puts washers on the snout bearing the Bendix stops against....reducing the amount of aft movement to the Bendix...so engages the fly/flex maybe 1/2 way......

then again Im told there are two different snout lengths to those starters....

damned If I know....I just know I had regular heavy weight POS, and the newer 'hi torque' gear drive thing....and in both cases I had to watch that install for moving it to the rear of the car....for some reason it's a chebby thing, never in all my years had a problem with a old Pontiac....just used the same shims it came with....fore/aft was never a issue I"m aware of anyway....:friends:
 
If your starter is like mine, you put a shim close to the engine to space the bendix gear farther away from the flywheel and on the outboard side to bring the gear closer to the flywheel. The instructions I had said to get it to where you could just get a large straightened out paper clip in the space between the valley in the flywheel teeth and the end of the tooth on the starter bendix. That way you have it tight enough not to damage the teeth and loose enough so as not to whine or hang up after the engine starts.
 
AJ77 said:
If your starter is like mine, you put a shim close to the engine to space the bendix gear farther away from the flywheel and on the outboard side to bring the gear closer to the flywheel. The instructions I had said to get it to where you could just get a large straightened out paper clip in the space between the valley in the flywheel teeth and the end of the tooth on the starter bendix. That way you have it tight enough not to damage the teeth and loose enough so as not to whine or hang up after the engine starts.
Click to expand...

U rite, but there is somehow a damn difference in the engagement of the teeth on these things...I dunno how/why....I saw the different wear pattern on my failed flex plate about a year after going to the 200 4r tranny, I never touched the flex....just swapped trannies...somehow that starter upon being reinstalled never engaged the full tooth width of the flexplate....upon changing that SOB, I checked that, something I had never bothered/had occation to before....
so when looking at the old flex it was apparent the wear/polish pattern there was never full tooth width engagement....there is NOW...damnit...

:crap::suicide:
 
i think i recall my starter had instructions for measuring the backlash by using a paper clip and it only came with two shims that were really thin like in the .002 range they could have been bigger but definitely inthe thousandsths
 
Due to manufacturing tolerances of the stamped steel flex plate, engines equipped with auto trans used shims between the starter and the block to assure correct tooth mesh between starter and ring gear. If the mesh is too tight, the starter gear will frequently not "engage" with the ring gear when the bendix slams the starter gear rearward. The mesh is measured with the teeth engaged, which means that it is nearly impossible to do when the engine/trans are installed in the vehicle - you measure it with the engine on an engine stand so you can get a measuring tool (such as a fat paper clip) inserted into the gears from the back side of the flywheel. When changing starters, GM recommends simply installing the same shims as you had before since measurement is virtually impossible. If your starter frequently "zings" into the flexplate without engaging, you can add a couple of shims to correct the problem.

I've never seen a case where the inboard or outboard side of the starter needed to be shimmed differently - this would serve no purpose. The shims are one-piece shims that span across both bolt hole locations.

Lars
 
Thx lars,

Question remains, is it okay for the starter sprocket to only go halve way the fly wheel or must it be fully engaged? If it must be fully engaged what can I do about it?

May be a little background is in order, I'm converting from auto to manual transmission (TKO600)
 
Hi

There is nothing you can do about this. 1/2 way is OK. Non of the starters engages the full width of the flywheel.

I recently installed a mini high torque starter. It came with 4 shims and even with all 4 installed, the starter did not engage , but hit the flywheel.

I had to install 6 shims to free the teeth enough to make it engage.
The paper clip trick can be used if you use needle nose pliers to fiddle them , from the starter side.

The GM starter that was installed had no shim.

The mini starter also only engages 1/2 or may be slightly more.

Kind of strange that GM did noit manage to manufacture this with closer tolerances. I never had to worry on any of my other cars, just install a new starter motor and go.

Rgds. Günther
 
Wesch said:
I recently installed a mini high torque starter. It came with 4 shims and even with all 4 installed, the starter did not engage , but hit the flywheel. I had to install 6 shims to free the teeth enough to make it engage.
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Günther -
I've had the same issue on 2 ministarters I have installed: They both took the entire shim package provided with the starter, and I still had to dig out a few original GM shims and add those, too. Luckily, I was on an engine stand both times, so checking the clearance was not a difficult issue. Both my ministarter installations were on manual trans cars, so I was surprised at the need for the excessive shimming.

Wesch said:
The GM starter that was installed had no shim.
Click to expand...

It would be unusual for a stock GM auto trans-equipped car to not have any shims installed - I don't think I've ever seen that on either Chevy or Pontiac. You sure somebody didn't remove the shim(s)? But if it was on a manual tranny car, GM did not have shims on the starter.
 
lars said:
Wesch said:
It would be unusual for a stock GM auto trans-equipped car to not have any shims installed - I don't think I've ever seen that on either Chevy or Pontiac. You sure somebody didn't remove the shim(s)? But if it was on a manual tranny car, GM did not have shims on the starter.
Click to expand...

Is that just cars or trucks? My 76 and 88 didn't have shims, nor the 81 Vette.
Click to expand...
 
In all my years working for GM and working on GM products, I have never seen a stock, virgin, unmolested GM car (yes, that means light duty trucks, too - it's the same engine, fer chrissake) with an automatic tranny with no shims in the starter. I'm sure the shim bucket on the assembly line went empty on occasion, but they didn't stop the assembly line for lack of shims...

Likewise, I've never seen a "Tom's Garage" re-install the factory shims when replacing the starter. The factory shims went in the trash can with the first starter R&R because they're a pain in the ass to re-install and nobody knew why they were there. Few cars (yes, that means light duty trucks, too) still have the factory shims between the starter and block (although my 82 Vette and my 68 GTO still have the original factory shim pack).

Lars
 
Hi Lars

My 68 is a orginal 4 speed close ratio M21 now having a GM T56 Viper 6 speed tranny in it.

It never was and never will be a automatic car.:tth:

I am happy to hear that you had the same issue with this mini starters I had. This assures that I didn`t do anything drastically wrong.:thumbs:

Thanks for the backup & brgds. Günther
 
Günther -
If your 68 is an original 4-spd car then it would not have had shims in it, so the configuiration was correct.

I don't know what it is with the ministarters and the amount of shims they need... but I've had to pack in nearly 1/8" of shims on the last 2 I did, even with 4-spd setups. I'm not sure what people do who don't have a stash of extra shims laying around - I guess they put up with the starter grinding against the ring gear every so often... But once they're properly shimmed they sure do work and sound good.
 
Back in the day when I worked at a Chevy dealer; we just used washers to shim the starter. And we usually used just one - on the bolt towards the engine. Not saying this is the best way but it seemed to work. Don't remember needing to shim the starters that often tho; but that was a long time ago. . .
 
Seems like I 'm a friggin' oddball on everything....'89 truck roller block mini starter, 200 4r auto...stock flex and NO SHIMS......I think I got the starter from AZ but no record just memory...thing is....I did have to replace the flex on account of some teeth lost....NOW the thing engages all the full tooth depth on the flex....and the depth of mesh is good....but NO shims....

so go figger....China crap?? it don't LOOK particularly cheep in the tooling....

:gurney::ill:
 
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