Strange starter noise
 

Hi folks. I'm piece by piece reassembling my '28 Tudor.


I bolted up enough to try cranking the engine today. Most everything worked, but I'm getting quite a bit of noise from the starter. Specifically, from the pinion gear engaging the ring gear. It sounds like a loud-ish clatter, and if I put a finger on the starter casing, I can feel impacts coming through the case.


My best guess is that somehow the pinion and ring aren't meshing correctly, but I don't see how that could be. The motor is tight, and runs smooth and strong on a bench. I don't see how the alignment could be off, everything's located by pins and machined flanges.


I did have the ring gear replaced when I had the flywheel ground to run true. Is there any possibility that somehow they used the wrong one?


Looking for ideas here. Any hints appreciated.

Re: Strange starter noise
 

Have you checked to see if the ring gear was installed correctly? Chamfered teeth to the rear.

Re: Strange starter noise
 

Yes, the chamfered corners are facing aft, toward the clutch.

Re: Strange starter noise
 

Gears have a pitch distance. It is the tooth to tooth distance at the pitch diameter. Since the ring gear has a large diameter you can just measure the tooth to tooth distance directly with a set of calipers. The gear on the starter is a little more complicated but it is the pitch diameter times pi, to give the circumference, divided by the number of teeth. The pitch diameter is roughly the diameter at half the tooth height. The pitch of booth gears should match within measuring errors.

If you or one of your buddies has an old ring gear you can compare that to the one in your car. That is easier than doing all the measuring and math.

It is possible that the Bendix is not working correctly which would limit the engagement. Look for witness marks on the ring gear that indicates improper engagement or other problems. Use a small mirror and light to look at the back side of the ring gear.

Is the ring gear seated all the way? It is a shrink fit and has to be heated and pressed onto the flywheel while hot and while working quickly. Look for a gap between the flange on the flywheel and the ring gear. There should be none.

Re: Strange starter noise
 

starter mounted correctly? And 3 bolts tight?

Re: Strange starter noise
 

The ring gear is seated well on the flywheel. There was maybe .010 gap against the shoulder, consistent all the way around.


Marks on the pinion gear indicate that it's engaging the ring about 2/3 of the way in along the teeth. Not all the way to the stop.



Starter is mounted correctly (the only way it will go, with the switch pointed up). Bolts are tight.


I know about gear diametrical pitch and how to measure. I haven't tried measuring it, but if it's wrong, does that not imply that the shop somehow came up with a ring gear with the right dimensions, but the wrong pitch? Does anybody even make such a thing? If there are no better ideas, I guess I'll check that tomorrow.

Re: Strange starter noise
 

Check the bolt lengths. Is there witness marks on the bolt closest to the ring gear? That should be the short one.

Re: Strange starter noise
 

Bob has a good point. There may be an overlooked factor like a bolt hitting the ring gear or something else. This will take some detective work.

Re: Strange starter noise
 

Wow, you learn something new every day. I didn't realize there was one short bolt. I'll check that when I get out to the shop. Thanks!

Re: Strange starter noise
 

There isn't one short bolt, all three bolts are the same 20388 3/8"-16x1".
The problem comes If you use to long of a bolt.

Re: Strange starter noise
 

Mismatched bolt would have been a better choice of words.

Re: Strange starter noise
 

The bolts are the correct 3/8-NC-1 dimension. No marks on any of them. The lower outside one (which is closest to the ring gear) has about 3/16 clearance.


A buddy who knows more about these cars than I do suggested that there was a shim kit, really a heavy gasket, which was used to tweak the mesh on these starters. I'll try that next.

Re: Strange starter noise
 

Bent shaft?

Re: Strange starter noise
 

It sure looks true when I spin it on a bench . . .


The noise isn't consistent with that anyway. It's kind of a rapid clatter/vibration. It seems about the right frequency to be every gear tooth. If it were possible to move the shaft out, so it was barely the tops of the teeth engaging, I'd say it was that. But there's nothing movable anywhere in there, the housing is located to the case by alignment pins, and the starter flange has a machined shoulder which mates with the housing. No wiggle room in any of those parts.


I haven't had a chance to try my gasket trick yet. That's next. I'll also try to capture a video with sound so you can hear what I'm talking about.

Re: Strange starter noise
 

Here's a quick video. You can hear the clacking noise. This is with the plugs out, it's somewhat more pronounced when it comes up to a compression stroke.


http://www.jrd.org/nate/05-07-22/MVI_0016.MOV

Re: Strange starter noise
 

All I get is a picture.
Is the Bendix and shaft clean, NO lubrication?? Bolts holding the Bendix to the shaft tight and locked??
Paul in CT

Re: Strange starter noise
 

I moved it to youtube: https://youtu.be/IMZ0mKpP0ks


The bendix and shaft are clean and dry. It slides smoothly on the spiral cuts in the shaft. The bolts are tight and locked.


Listen to the sound. I don't see how that's consistent with the bendix sticking or misengaging.

Re: Strange starter noise
 

Other than what looks like a 12 volt cable from the battery. Not likely to be problem.


I see that the shift tower is for a 28.


If a 28 flywheel is on there the Bendix bolt could be hitting the flywheel as it turns.


Maybe bolt used is too long?



Sounds kind of like that...


Pull starter and look at the top of the bolt on the end of shaft for damage.


28 fly wheels are different from later. I do not know what happens with 28 flywheel but that is what it sounds like to me.

Re: Strange starter noise
 

Maybe the Bendix bolt is correct but the end of bolt is not engaged in the hole in the armature shaft so in effect bolt is too long.


Photos might be needed to fix this one!!

Re: Strange starter noise
 

A buddy of mine (who knows way more than I do about these cars) came by and we played around with it for bit.


Tried shimming the starter, no effect.



We pulled it all out and checked that the shaft is running true, and there's nothing hanging it up on the shaft.



Put a bit of sharpie on the gear teeth to make sure we could see where it's meshing, That looks fine, close to the center of the pinion gear.


There are no marks anywhere on any of the bolts, no evidence of anything interfering there.


This is the same flywheel that was on there, with this starter and bendix. So I don't see why it would have started interfering now. And there are no marks on anything anyway.



The best guess at this point: This ring gear was replaced, but this is the pinion gear that's been in there forever. The old ring was pretty ratty looking. Maybe both gears got worn over time, and now that the ring got replaced, the pinion isn't meshing clean. I'm looking at buying a new bendix drive/gear and swapping that on there. Then at least everything will be new.