MTFCA Forum

Two of us in our group have put on new alternators within the last month and they both make noise, mine knocks, I can actually feel it. Has anyone else had this problem and does shimming it help? I am getting ready for a trip and really don't like the knock. Thanks, Dennis

I've seen examples where the gears have come loose on the alternator shaft. You should probably remove & inspect it.

Thanks Jerry, for the quick response, I am on the way to check it now. Dennis

Well dang it, the gear was tight but thanks for the idea.

What went wrong with the generators?

Allan from down under.

Is alternator in the same mounting area that the generator was located? Was your gear fully engaged with the timing gear? I’ve read about issues with a certain supplier where the shaft is short and the gear is recessed partially from the timing gear and it created a poor alignment/gear mesh.

Proper gear mesh is as important as with a generator mounting. Paper shims are used under the generator mount. Those things are not gaskets.
Be concerned with the way the gear is held. Very common to have a C pin instead of a roll pin(better) Or as originally done - A solid peened steel pin. Those C pins shear & can get caught in the timing gears. This is a common tour failure.

Going from a generator to alternator was an economic decision, my generator served me well for over 120,000 miles and needed replaced, the gear on the alternator is the same dimensions as the generator and the gear is threaded on to the alternator so no pin to worry about. I will try shimming the mount housing and see what that does.

Can you use your original generator gear on the alternator. Its gear will know your cam gear. Otherwise the new gear will have to develop that relationship/

Allan from down under.

Dennis Prince wrote: ↑

Fri Jul 04, 2025 11:25 pm

Going from a generator to alternator was an economic decision, my generator served me well for over 120,000 miles and needed replaced, the gear on the alternator is the same dimensions as the generator and the gear is threaded on to the alternator so no pin to worry about. I will try shimming the mount housing and see what that does.

Before you remove the genny mount, reach in thru the oil filler with an electricians screwdriver.
If the gear has any free play its not too tight.

Allan wrote: ↑

Sat Jul 05, 2025 12:24 am

Can you use your original generator gear on the alternator. Its gear will know your cam gear. Otherwise the new gear will have to develop that relationship/

Allan from down under.

... the gear on the alternator is the same dimensions as the generator and the gear is threaded on to the alternator ...

It would appear that it's not possible to do so.

What is the condition of your timing gear? Do all the teeth look good?

The cam gear teeth all look good, I put another gasket between the housing and the block and just waiting for the sealer to dry. In the mean time I will take my Model A for this mornings drive to the shop tour of one of the group. I will update you later. Thanks, Dennis

Well, that took care of the knocking noise and I talked to the other T owner with a noise and he said that after driving it a bit that the noise is considerably quieter, so I think that our problems are over (for now), Time to pack up and get ready to head to the Motor Camp at Tahoe. Thanks to all for your help. Dennis

Great! Happy you got it solved.