Why Would You "shim" a 928 Starter?
#16
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#18
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That bracket bolts to the engine bolt and is designed to hold the starter at a perfect 90 degree angle to the flwheel.
The only reason (I can think of) to put a shim under one of the starter bolts is that the starter is not perpendicular to the flywheel, any longer. Logically, the fact that the shim is under the lower bolt indicates that whatever is the cause, it is from the front angle of the bracket being greater than 90 degrees and consequently, the rear angle being less than 90 degrees.
The flwheel bolts to the crankshaft....pretty difficult for it to not be perpendicular to the crankshaft.
The starter bracket bolts directly to the block and locates on four factory machined pads that are perpenducular to the crankshaft. I guess if someone hit the starter bracket hard enough, those pads could break out of the block....however, I've never seen this.
Logically, that leaves the bracket, itself, to be the most likely candidate to be the problem.
If the car is a manual transmission, pretty straightforward to replace the bracket. If it is an automatic, replacing that bracket is an involved process.
The only reason (I can think of) to put a shim under one of the starter bolts is that the starter is not perpendicular to the flywheel, any longer. Logically, the fact that the shim is under the lower bolt indicates that whatever is the cause, it is from the front angle of the bracket being greater than 90 degrees and consequently, the rear angle being less than 90 degrees.
The flwheel bolts to the crankshaft....pretty difficult for it to not be perpendicular to the crankshaft.
The starter bracket bolts directly to the block and locates on four factory machined pads that are perpenducular to the crankshaft. I guess if someone hit the starter bracket hard enough, those pads could break out of the block....however, I've never seen this.
Logically, that leaves the bracket, itself, to be the most likely candidate to be the problem.
If the car is a manual transmission, pretty straightforward to replace the bracket. If it is an automatic, replacing that bracket is an involved process.
#19
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Turns out the starter has been replaced. Bosch core 0-001-312-102 "World Class" is the reman. Can't tell yet if the bracket is bent. Will have to remove. The third photo down does look like it is bent if you follow the alignment along the lower clutch housing?
#20
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#21
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Took the starter over to Advanced Auto parts to test. It would not fire for them. Machine said it failed test. Went across the street to Autozone. It fired for them after a second try but the machine said there was some voltage problem. Now who do I believe?? Are these machines by these parts stores rigged to fail parts that you bring in order to sell you parts. If I replace the starter, what re-manufacturers are reliable ? I assume a reman by Bosch?
#22
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So the starter was starting the car OK, correct? Just an extra "grinding sound", from your original post. And someone in the past replaced the starter (long before its use-by date) with a rebuild, and then added some beer-can scraps under the lower mounting-bolt to fix something. And there are some gouge-marks at the bottom of the bracket at a strange angle.
This all seems to point to (a) the starter is fine, (b) the bracket got bent, somehow, and (c) the grinding sound is most likely due to the bent bracket.
So I see two choices: Pull the clutch and flywheel, remove the bracket and check it for flat (or just replace it), and reassemble; Or, put the starter back in, maybe with some extra shims to see if that solves the grinding noise, and do the clutch/flywheel R&R later. Starters aren't rocket science, if the engine starts OK and the starter disengages once started, then that's about all you can ask of it.
#23
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"So the starter was starting the car OK, correct? Just an extra "grinding sound", from your original post. And someone in the past replaced the starter (long before its use-by date) with a rebuild, and then added some beer-can scraps under the lower mounting-bolt to fix something. And there are some gouge-marks at the bottom of the bracket at a strange angle."
Correct, Jim. I know from looking that the clutch would have to be dropped in order to remove the bracket to check. My thought this morning is to find a starter rebuild shop and have them test the starter and pick their brain about shimming etc. Looking again at the flywheel with the lower cover removed, everything actually appears normal. The starter gear looks good. (see previous picture) The only thing I found was some tiny scraps of shims (?) wedged between the starter bracket and flywheel which left some scrape marks on the backside of the flywheel. Not gouged just "polished" the flywheel.
My questions is: How does one go about measuring and shimming a starter?
Correct, Jim. I know from looking that the clutch would have to be dropped in order to remove the bracket to check. My thought this morning is to find a starter rebuild shop and have them test the starter and pick their brain about shimming etc. Looking again at the flywheel with the lower cover removed, everything actually appears normal. The starter gear looks good. (see previous picture) The only thing I found was some tiny scraps of shims (?) wedged between the starter bracket and flywheel which left some scrape marks on the backside of the flywheel. Not gouged just "polished" the flywheel.
My questions is: How does one go about measuring and shimming a starter?
#24
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Personally, I wouldn't shim it and wasn't seriously suggesting that you do that. The right way to fix this is to drop the clutch and flywheel, and replace the bracket. And check the block for damage, that is a beefy steel bracket bolted to an aluminum block.
But if that is not practical, and you just want to do a quick fix and drive the car, then consider adding shims (or a washer or two)-- I suspect that grinding noise was the pinion binding from the starter nose being pushed into the bellhousing. The nice thing about the bracket on 87+ cars is that you can mount the starter with the lower bellhousing cover off and check the clearances. Just extend the pinion with a screwdriver, turn things by hand and check for clearance. Adding more space at the bottom of the starter moves the pinion away from the ring gear. But this is a hack, there is no point in getting fancy with it.
That's my two cents, others have different ideas.
#25
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I had the starter yesterday tested for a third time by a machine/starter rebuild shop. He said the solenoid is bad. I had no reason to suspect he wanted to sell me a starter since they just rebuild them. He could not find a listing for a solenoid from anybody including Bosch. I ordered a Bosch re-man. When I get the new re-man Bosch I will check the clearances and engagement and report back.
#26
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If you do want to check the starter pinion alignment to the flywheel ring gear, get a tube of engineering blue, apply it to the faces of the pinion gear, engage the gears, and then examine the contact areas revealed by the areas on the teeth of the gears which show contact. They should be nearly centered to the width of the teeth on the pinion gear and pretty much identical. An offset from center shows a misalignment, i.e. the axes of the two gears are not parallel, IOW something's bent..
#27
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I've seen a couple of videos how to measure and shim starters. Basically there are two adjustments to check. One being the engagement depth to the flywheel should be between 1/2-2/3 of the starter gear. The other measurement is the depth of the teeth to the flywheel. Do these make sense? The Bosch re-man should be here this week and will check these measurements.
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#28
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I've seen a couple of videos how to measure and shim starters. Basically there are two adjustments to check. One being the engagement depth to the flywheel should be between 1/2-2/3 of the starter gear. The other measurement is the depth of the teeth to the flywheel. Do these make sense? The Bosch re-man should be here this week and will check these measurements.
.
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Don't give them the old one as a core, until you try and install the "new" one.
You'll understand, shortly.
BTW....A few American starters need to be shimmed, due to production tolerances. These shims go under the entire mounting of the starter, not under just one end!
You've been told, several times, what the problem is, if you need to "shim" a 928 starter under one bolt.
You don't seem to be listening.....
Your starter is no longer parallel with the crankshaft centerline, caused by a bent bracket (or worse), if you need a single shim under one bolt!
Last edited by GregBBRD; 12-11-2017 at 12:36 PM.
#29
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You've got a whole new set of adventures coming, with a reman Bosch starter....
Don't give them the old one as a core, until you try and install the "new" one.
You'll understand, shortly.
BTW....A few American starters need to be shimmed, due to production tolerances. These shims go under the entire mounting of the starter, not under just one end!
You've been told, several times, what the problem is, if you need to "shim" a 928 starter under one bolt.
You don't seem to be listening.....
Your starter is no longer parallel with the crankshaft centerline, caused by a bent bracket (or worse), if you need a single shim under one bolt!
Don't give them the old one as a core, until you try and install the "new" one.
You'll understand, shortly.
BTW....A few American starters need to be shimmed, due to production tolerances. These shims go under the entire mounting of the starter, not under just one end!
You've been told, several times, what the problem is, if you need to "shim" a 928 starter under one bolt.
You don't seem to be listening.....
Your starter is no longer parallel with the crankshaft centerline, caused by a bent bracket (or worse), if you need a single shim under one bolt!
Greg,
I should have reported that there were an equal amount of shims on BOTH bolt mounts once I got it down. My bad. So if a Bosch re-man is "not desirable" what is the alternative from brand new Porsche OEM? I would consider a mini high torque.
#30
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Get that Bosch rebuilt and let everyone know how it works out.....I keep hoping Bosch will figure out the problem and they will go back to the original starter....maybe yours will be the one!
Porsche doesn't rebuild their own starters (I'm betting they use Bosch), but they might have old inventory.
I think I'll check into that, myself.