Hi-Torque starter motor.

[DaveEFI]

Quite some time ago, I imported one of these for my SD1 from the US - as they were considerably cheaper there. It's a bit of a cottage industry using standard bits with a custom made 'flange' to fit the particular vehicle. It has a small permanent magnet motor which runs at a higher speed than the normal Lucas one, and reduction gearing. Result is said to be higher torque and less current draw.

It was lying around for quite some time before I fitted it. Worked ok at first - but then started failing to engage with the flywheel. So the motor would simply whizz round without turning the engine. A few attempts, and it would eventually engage. But this could take 5 minutes or more on a cold day with cold engine. Once the engine was hot, it would usually engage right away.

I've now had a similar Rimmer unit fitted which is fine. So want to repair the old to either keep as a spare or sell.

Think I asked here about what was likely to be the problem, and was told it would probably be the sprag clutch. But with the unit off the car, you can turn the pinion one way - but it seems to lock solid the other way.

I'm not familiar with the design - anyone know of a site which gives stripping and checking etc details? All I can find is lots of people selling them.

[SimpleSimon]

Hi Dave yes it could be the sprag clutch slipping (hard to simulate off the car) should freewheel in one direction then lock hard the other way, try to rotate the pinion in a clock like motion pushing back every so often sometimes you will feel it slip it is this part that during cranking if it finds this it will continue to do so and wont bite, basically fitted to stop you over driving the starter if your stupid enough to keep the starter engaged after the motor is running which I know you are not

[DaveEFI]

Thanks for the explanation - so just replacing the clutch should sort it?

Think most would wait until the engine starts before releasing the key, and the idle speed is always going to be much higher than cranking speed, so a way of coping with this has probably been needed since starters arrived.