DDK - Die Deutschen Klassiker

At the Shere Hillclimb the other day my car developed a horrendous screeching noise when cranking on the starter, but ran perfectly once started. I suspected the starter itself might be on the way out, although it did continue to work all day inspite of the noise.

Having just pulled it today, i’ve found a broken tooth on the flywheel ring gear. Clearly an engine-drop required to replace the ring gear. However, am a little concerned about whether there may also be something amiss with the starter too, in order to cause the damage in the first place. A single broken tooth doesnt really seem consistent with the more continuous screeching it was emitting during cranking.

Anyone here bench-tested a starter motor? This one looks ok on the face of it - its a high torque version by “hi-performance of America” which I fitted about 12 yrs ago. I’d like to be sure it doesn’t eat the next ring gear for lunch too though!


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Starter gear looks ok to me


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… although a bit of tooth damage is apparent when you zoom in


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Yes you can bench test the starter. Lots of videos on YouTube showing how to connect it. The gear should move forward and spin

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IMHO there will be little wrong with the starter, just the lead-in form of the teeth.
There are various UK based manufacturers of these starters who could help i think, can't recal the name now but I and Andy Lightweight have them and I'm sure many others.
Give them a call tomorrow?
The drive train has to come out of course and a fresh ring installed. I've never seen a ring fain mind like that and my 3.2 starter ring has 140+K miles on it and so a lot of 'starts'
I would think the lead in flats on each starter gear is quite critical to engagement.

I'm sure Graham you are right... but starter motors seem to have been the bane of my life (one of many perhaps ). One of the problems is where the pinion for whatever reason doesn't throw out and engage well enough. Then it wears, engages less and gets into a vicious circle.

Thanks folks - agreed: I think this is an issue with the profile on the nose of each tooth on the starter pinion. It seems to have a flat face which cant be helping to engage the ring gear in a mechanically sympathetic way…. I’m quite sure the original Porsche pinion would not have created such damage.

I’d love to see the tooth profile on the stock Porsche starter pinion, but unfortunately i sold mine a decade ago - moral of the story: never get rid of anything!

Currently in process of removing engine and gearbox. I think i have a spare ring gear somewhere, but i dont want to refit the current starter. I wonder if its worth attempting to replace the pinion? Will do some research on alternative starter options too


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Here's a case in point. Caterham xflow starter that wasn't throwing out properly. New pinion fitted and hopefully it'll work ok. The motor has had a rebuild too with a lightened flywheel and new ring gear. One of the problems is to see whether it engages cleanly or not when it's used...
IMG_20220108_123959 by graham Ridgway, on Flickr

Mmm, not pretty. Was it straightforward to obtain another pinion?


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Yes very easy

I should add that was for a Lucas starter motor

On the Powerlite website i see that their starters have a couple of different bevels on the tooth edges. See pic here. Subtly different from mine. I’ve also seen comments on Andy Prill’s website, where he sells Powerlite starters, that flywheel damage has been a recognised issue with some other aftermarket starters.

Tempted to try the Powerlite.




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Looking at the photos of yours and the powerlite one, the two bevels look very similar to me.

I think the squealing might have been the starter motor bearings as the motor teeth crashed over that broken flywheel tooth.

That tooth obviously had a microcrack in it, which has grown throughout years of normal operation, and now failed.

In my opinion, your existing starter is not going to do any harm to the new flywheel, so you could safely give it a try and see how it sounds before opting for a new one... just my opinion

Fwiw
Agree with above.