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Triumph TR3 - Sticking Starter Pinion

Greetings from the garage,

After suffering the disintegration of my starter coming back from TRA (the end cap unscrewed and bits shot around and through the bellhousing), I rebuilt the unit with parts from a beat-up starter purchased through E-bay. You can be sure there is now a cotter pin installed through the end of the armature shaft. Let us pray...

My problem is that, when I operate the starter, it turns the flywheel until the engine catches, then I get a horrific grinding noise from the starter. I believe the pinion is stuck against the flywheel rather than releasing after the motor starts.

The replacement pinion gear I acquired is nonstandard, but it would seem ok to use. The gear teeth run the length of the replacement pinion, rather than halfway as with the stock pinion.

What should I be looking for to unstick the pinion gear? The parts are clean and dry, and they seem to move easily on the armature shaft. Clues?

Pix of the starter parts and pinion gears can be seen at: http://www.cardomain.com/id/motopsyche. You'll readily notice the worn teeth from the damaged pinion gear.

Thanks for your help.

Bill Stagg
1961 TR3A
Bill Stagg

I have the early "bullet nose" starter so I'm not at all familiar with your design.

Don Elliott
Don Elliott

Is this a stupid question? Why didn't you use the old gear? Just wondering. Both my starters of that style are in cars. But it seems like the pinion does have angled edges, I think to kick the pinion back with engine revs.

One of those new nippon/adapter things would be tempting. I hate not trusting a starter.

Did you stitch up the bellhousing? If not, maybe you can watch what happens thru the hole. I have a tranny in a car that's been welded along the top lip (somebody used the nuts to take out the clearance, rather than pushing home) with no problems, musta been a few craftsmen back then.
Tom

Here's a pretty good pic of one for sale, good price right now, too.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33576&item=7913033865
Tom

Tom,

The old pinion was worn pretty badly, probably from driving home with it engaged (or partially engaged) with the flywheel ring gear. If you look closely at the pix, you'll see significant wear on the end with the angled the teeth. The angled portions of the teeth are, in fact, gone, leaving a scooped-out appearance to the remaining teeth.

I did receive a suggestion from another TR owner who tried to use the same "larger" pinion gear as I have. He reports he had the pinion ground down to match the old pinion gear. Possibly reducing the mass of the gear affected the drag on the shaft. In any event, he said it now works fine. I may give that a try today.

Thanks for the help.

Bill
Bill Stagg

Gents,

Just curious: It is possible that the pinion gear would "stick" to the flywheel ring gear if there is grease or other muck on the ring gear teeth? Is it necessary or worthwhile to clean the ring gear teeth?

Bill
Bill Stagg

I have 2 pinions for my TR3A (early) starter for my "older bullet nose" starter with the teeth worn back about 1/8". I was wondering about having the worn end turned off to make the pinion body shorter and then use a spacer at the other end so the teeth would be "long enough" again to engage the fly-wheel ring gear. I would also grind the chamfer lead-in angle back on.

Any thoughts on this ?

These would be for spares as they are no longer listed new in suppliers catalogs.

BTW Bill have you driven the car through all the gears since you did that rolling, bumping, pushing start in reverse ? If so, have you had it popping out of 2nd gear or not ? Have you heard or experienced any "crunching" or "crashing" as you go into 3rd gear ?

If not, your gearbox may be OK.

Don Elliott
Don Elliott

Don,

The gearbox was working fine after the reverse bump start. No problems there, I believe.

I just got my starter working. Here's the list of things I did before reinstalling:

1. Ground off the excess portions (and weight) of the pinion gear teeth so that it now matches the profile of the standard pinion.
2. Elongated the hair spring a bit to give it more, er, spring.
3. Applied dry graphite to the moving/sliding parts of the starter. Smooth like butter.
4. Degreased the teeth on the flywheel ring gear.
5. Used a BFH to coax the armature spindle back into a straighter orientation. It was slightly bent.

Hooked up the starter and voila! It turns and disengages properly.

I like your proposed fix for the teeth, Don. Let me know how it works out.

Thanks to all!

Bill
Bill Stagg

I love the BFH fix. Only a LBC car guy would have the guts to do that. And the touch to get away with it!

You guys sure have great ideas for keeping these babies on the road!

I kinda wish the starters were gone completely so I could justify a nippon replacement. Oh, maybe not. I have dreamed of putting a Mitsubishi V6 in, too. but that'll never happen.

On the subject of starters, I bought a later style one on ebay, needing field windings. But the spring is made from square wire and the pinion looks similar to the older style. I'll have to compare parts with the old style spare I have in storage. Probably from an MG or something. But it had the same numbers on the case as the late one I was working on. So I switched cases, windings and all, very easy switch. And the starter has been working for more than a year now. Occasionally it will disengage when the engine pops and dies, but other than that, perfect.

Just another thought, maybe a shim between the starter and the block would help my occasional "pop out". But the older starters worked the other way, didn't they? Don needs to add a spacer behind the gear (or machine off a bit of the flange) to replace wear, later models need a starter shim, correct? Or am I barking up the wrong tree?
Tom

Tom,

The BFH fix is not for the faint of heart. Having a spare spindle on standby (albeit even more bent) gave me some degree of courage).

I'm curious about the "popping out" you mention. My starter will disengage almost the moment the engine first fires. If the engine doesn't keep running, I have to let the starter finish spinning down, then restart.

Can this be adjusted by shimming? Is it possible the gears are not engaging sufficiently to "hold" the starter beyond the initial pop? Or is the starter designed to "pop out" at the first sign of a plug firing?

Bill
Bill Stagg

That link from ebay has a starter with a shim included. I don't think any of my TR's have had a shim on them. Maybe I'll have to try one. Seems like it would move the gear just a bit closer to the flywheel.

But the bomb starters work the other way, right?
Tom

My early bomb starter pinion on my TR3A (TS 27489 LO) spins out from the front of the car towards the rear. Spinning this way, the teeth on the pinion are the first to engage the ring gear on the flywheel. My ring gear is shrunk fit (I had to heat it up to get it on - then it cooled to a tight fit. The chamfers on the ring gear face the front of the TR for easy engagement with the lead-in chamfers on the teeth on the pinion. These face to the back of the car.

I have heard of later ring gears which are bolted on.

I have also hear of some TR's where the ring gear moves forwards (or backwards - can't remember) and the starter pinion cannot engage the ring gear correctly. It misses or clashes. Can't remember.

For the correct answers on this, try the TR6 archives below.

Don Elliott
Don Elliott

Bill I noticed in the Moss cat. part # 549-430 starter mounting shim. Says it was originally fitted on most cars but usually lost the first time the starter was out. On the early starters like Don's ( and mine) it pushes the pinion away from the ring gear. On your style starter , it brings the two closer together. I can't say that I have ever seen one. Brian
B. Towne

Thanks for the heads up on the shim, Brian. I probably missed my opportunity to visually inspect the engagement of the starter pinion and flywheel while I had the gearbox and clutch removed. I should have mounted the starter and observed it in operation at that point. I also just missed employing Don's tip about inserting the bolt from the rearward side of the gearbox, making it easier to mount and dismount the starter. I may pick up the shim and check out the performance.

Thanks, again!

Bill
Bill Stagg

This thread was discussed between 31/07/2004 and 06/08/2004

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