Lotus Elan

Grinding gears!

PostPost by: dgently » Fri Jan 20, 2017 4:00 pm

ringgear1.jpg and
My replacement starter worked well for a year then began making horrible grinding noises while turning the engine some time back, and a little later the pinion gear broke off.

It?s a Denso-style pre-engaged starter with a 9-tooth pinion. The pinion was pretty beaten up, about half the tooth height ground off the front half of its length (which points to the back of the car). It replaced the original Lucas 9-tooth, and I've no reason to think my ring gear is anything other than the normal 110-tooth (1968 +2)

I sourced a replacement pinion with ancillary bits (spring, collar etc), (9-tooth and visually identical) and my friendly local auto electrician (lets call him Frank) fitted it to the starter for me. Frank was adamant my ring gear must be badly worn, loose or damaged somewhere, so I checked it carefully all the way around. No damage found, and the wear seemed reasonable (see attached photo).

Starter with new pinion was noisy from the outset, and now its grinding without turning the engine. The engine isn?t seized, feels 100% normal when you push it in gear.

I?m out of ideas, and I can?t summon the will to pull that starter again. It is seated perfectly and tightly bolted to the bellhousing, there?s zero play in the shaft, I?ve treble checked that my (many) pinions are the right (29.15mm) diameter, and I everyone I?ve shown this picture to agrees that the ring gear looks fine.

Why oh why won?t it turn that ring gear?
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PostPost by: danielmo » Fri Jan 20, 2017 6:04 pm

At a glance, that ring gear does not look like a 110 tooth one, but I could be wrong. Can you mark the flywheel and count the teeth while in the car?
Last edited by danielmo on Fri Jan 20, 2017 6:07 pm, edited 1 time in total.
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PostPost by: nmauduit » Fri Jan 20, 2017 6:07 pm

is it adequately aligned so that the pinion engage smoothly but snug? not so easy to have a peek but maybe worth it to help diagnose where it sticks (I assume operation is good when unmounted, smooth and strong)...

good luck !
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PostPost by: types26/36 » Fri Jan 20, 2017 6:40 pm

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Last edited by types26/36 on Sat Jan 21, 2017 7:52 am, edited 1 time in total.
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PostPost by: Robbie693 » Fri Jan 20, 2017 6:58 pm

Or maybe remove the pinion cover in the bell housing and observe what happens while trying to turn the engine over...?
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PostPost by: Chancer » Fri Jan 20, 2017 8:11 pm

types26/36 wrote:
dgently wrote:Starter with new pinion was noisy from the outset, and now its grinding without turning the engine. .


Sounds like the internal clutch on the bendix is slipping, probably not what you want to hear but I would take out the starter, clamp it in a vice and apply power. While it is spining jam some wood on to the teeth and see if the teeth stop tuning while the starter is still turning.


No bendix on a pre-engaged starter but what you say otherwise is valid, if the noise is more of a squawking than a grinding then it could be the one way roller ramp clutch that is slipping Under load, it will still probably have enough drive to shred your bit of wood doing the test though.

If it were a series production car that hadnt been molested I would say it was that but most of these aftermarket starters are very hit and miss on pinion engagement depth so check that first
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PostPost by: types26/36 » Fri Jan 20, 2017 8:47 pm

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Last edited by types26/36 on Sat Jan 21, 2017 7:51 am, edited 1 time in total.
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PostPost by: bob_rich » Fri Jan 20, 2017 8:56 pm

Hi

I would definitely try to count the teeth on the flywheel. When I had my engine rebuilt I had a problem in that a 132 tooth ring gear was incorrectly fitted and after a short time the teeth on the flywheel ring were ground off and engine would not start. Engine was pulled an then a 110 gear was fitted and the wasp pre-engager started worked fine. Symptoms were just like yours worked for a bit them grinding graunching and not cranking of engine.

this was just an organisation cock up between engine builder and me after fix, had no problem since

hope this helps best of luck

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PostPost by: Chancer » Fri Jan 20, 2017 11:11 pm

Peace be with you type 26/36.

It was an innocous comment, or so I thought! It was not my intention to offend you but to offer help to another forum member so please accept my apology.
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PostPost by: dgently » Mon Jan 23, 2017 2:14 pm

OK, I went under to try to get a look at it from the hole opposite (on the back of the bell-housing). I had my kid turn the starter, and I could see that the starter pinion was spinning freely while the ring gear was only occasionaly tuning a bit (maybe a ? turn)

I hooked up a positive feed to the shaft actuator (that's supposed pre-engage the pinion) without activating the starter so I could get a look at that (see pic below).

I honestly don't understand what I'm looking at. The engagement depth seems OK (top of the pinion is ~1mm beyond the back of the ring gear) but it looks misaligned, as if the shaft centre should be 2mm or 3mm closer to the ring gear centre.

The starter itself seems correctly centred, the pinion diameter is 29.15mm, so how on earth can my ring gear be that far away?

Just to reiterate, engine will start and sounds fine. Nothing could be disastrously wrong, right?
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PostPost by: ericbushby » Mon Jan 23, 2017 3:08 pm

The starter pinion teeth should be engaged deeper with the ring gear teeth than that. Further use will only cause more damage.
Is there something wrong with the mounting of the starter motor in it`s mounting ring. From the photo, it does not look to be centred correctly. It could just be the angle of the photo.
I suggest you take it out again and check it over.
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