starter grinding on 3.4 (Page 1/1)
Rsvl-Rider DEC 11, 09:15 PM
1988 GT auto with 3.4 swap. Starter had been working reliably in the car since I bought it 8 years ago.

I replaced the starter on my daily driver about 4 months ago due to weak cranking. The new starter looks identical to the old one. I re-used the original spacer/shim as recommended and it worked fine until recently when it started grinding. I stop cranking immediately and then it starts without grinding on the next try. After the third incident I parked it until I could pull the starter to take a look.

I suspected that maybe the starter gear was not extending fully causing incomplete engagement. I applied voltage to both the old and new starter side by side and the gear extended strongly and equally on both starters. So I suppose this would indicate that maybe the starter gear is not positioned close enough to the flywheel. Should I leave the spacer out on the next starter??? I wonder how much difference this would make since the spacer is so thin.

As you can see in the closeup picture the gear teeth on the new starter are rolled over, but the teeth on the original starter look similar. Is this the result of the grinding, or is it made that way so that the teeth can mesh wth the flywheeel easier???

I would appreciate any feedback.

New starter



Old starter
pmbrunelle DEC 12, 12:14 AM

quote
Originally posted by Rsvl-Rider:
The new starter looks identical to the old one. I re-used the original spacer/shim as recommended and it worked fine until recently when it started grinding.



The reason for the presence of a shim is that every block/ring gear/starter combination is unique, so a shim of the correct thickness is selected to make that particular combination have the right amount of gear tooth clearance.

The original shim you had may be correct for the new combination of parts, but not necessarily.


quote
Originally posted by Rsvl-Rider:
As you can see in the closeup picture the gear teeth on the new starter are rolled over, but the teeth on the original starter look similar. Is this the result of the grinding, or is it made that way so that the teeth can mesh wth the flywheeel easier???



What do you mean by "rolled over"? I do not understand.
Rsvl-Rider DEC 12, 02:23 AM

quote
Originally posted by pmbrunelle:

The reason for the presence of a shim is that every block/ring gear/starter combination is unique, so a shim of the correct thickness is selected to make that particular combination have the right amount of gear tooth clearance.

What do you mean by "rolled over"? I do not understand.



I undestand the use of the shim. What I am saying is that it seems like if my issue is to get the starter gear closer to the flywheel, that even by removing the only shim it does not seem that it will make much of a difference if the current set up is so loose that the teeth are getting rolled over (bent over). See the pics. the teeth seems to be leaning to the left.

Also I don't get how the corrrect shim is determined without trial and error. Grind or not grind?
pmbrunelle DEC 12, 08:39 AM
The starter pinion teeth look like that after they are cut; it is not due to wear/damage.

To prevent an undercut (which makes teeth narrow at the base, and hence easy to break), low tooth-count gears (such as a starter pinion) are typically cut with a profile shift.

The profile shift means the cutter doesn't cut as deep into the gear as usual; this prevents the undercut, and makes the base of the tooth wide and strong.

https://khkgears.net/new/ge...r_profile_shift.html

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Check in Ogre's cave Powertrain>General Engine>Starter for some suggested methods.

The starter doesn't hang on after startup when the engine is running?

You have to remove the sheetmetal bellhousing inspection cover to get a peek in the starter gear mesh area.
ArthurPeale DEC 12, 02:42 PM
Can you post a video of what it's doing? From the outside of the car. I'd like to hear the noise.
theogre DEC 12, 06:42 PM
Yes, using old shim w/ new starter often doesn't work.
May look same but tiny bit of metal change where starter bolts to engine can make old shim not fit right and starter or worse engine gear have problems.
See my Cave, Starter

New or Rebuilt Starter can be bad by itself and die out of box or soon.

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Dennis LaGrua DEC 16, 09:30 PM
You are supposed to use the right shim with the starter but you cannot set the clearance with the feeler gauge as you cant fit it in there and pull the gear forward. My recommendation is you paint the starter gear white, install it turn it over and watch the gear to see where the contact points are on the gear. Judging by the contact area that will indicate whether clearance is right or wrong.

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