Starter motor problems Options

[DaveO90s4]

Hi all, i am having real problems with my starter motor and hope someone will be able to provide advice about a tried and proven solution

I am running a reverse rotation (eg normal Porsche rotation) Chev Corvair engine with the Kennedy Engineering VW (not 914 / 901) adaptor mounted to my oem 914 / 901 transmission), using 130 tooth ring gear on VW flywheel. Engine, clutch, gearbox etc all work well together.

This set up places my ring gear further away from the starter motor than OEM 914, by about 6mm

Problem 1. My OEM 914 starter motor engages in the ring gear smoothly and sufficiently to start the engine, but when hot the starter motor acts as if the battery is flat. I amtold that this is called ‘heat soak’.

So I ordered a new starter motor - an IMI hi torque starter- with a longer pinion at rest distance to allow for the greater distance between pinion and ring gear. This was supplied with a 9 tooth, 25 mm pinion, as per the OEM starter motor.

Problem 2. The new IMI starter motor worked fine initially, but has increasingly failed to engage on the rong gear properly. Instead of turning the engine, very often the pinion and ring gear ‘screech’ with no engine rotation.

I googled this issue and it seems a not uncommon problem with IMI hi torq starter motors and VW / Porsche ring gear. In those cases the problem was overcome by using a 10 tooth 27 mm diameter pinion. So i bought one of those.

Problem 3. No improvement. The 10 tooth 27 mm pinion is no better.

I have since been advised by Kennedy Engineering that - due to similar issues with other installations - they have now switched to the WOSPErformance hi torque starter motor.

In an ideal world I think I’d buy a decent irdinary non hi torque starter motor that bolts directly to the 901 transmission, but that had a longer shaft by about 6 mm.

I would welcome any suggestions that will help me overcome these problems I am having.

Many thanks in advance

DaveO
Australia