Rb25 Starter Motor Comparison - Halp

[Granthem]

Hi guys,

Interested in your opinions on the teeth of the below starter motors.

The starter on my S2 R33 has been getting pretty lazy for a long time now. Its part number is 23300 08U15. I am running a Cusco chromoly flywheel but I doubt this affects anything.

Pics of the starter motor 08U15 I removed are attached and marked "original starter".

I obtained a second hand replacement from a friend (labelled "new" in the images), which was removed off his RB25 (S1 however). Part number is 23300 08U10. The unit itself on the outside is identical, solenoid position etc all match.

Inside they are slightly different re the number of magnets etc - but I am not concerned with that. My concern is the teeth which engage to the ring gear are completely different. I counted 15 on this unit, but not only that, the circumference of the teeth appear to be a lot smaller.

I have read that all RB starters are interchangeable - I simply want to check that, against the images contained within.

I note I didn't find another thread with pictures like this.

Anyone have an opinion on whether the different teeth with affect engagement with the flywheel? Hoping to bolt the new one back in tonight and I don't want to do any damage!

[GTSBoy]

As long as the teeth are the same height (each, tip to base of tooth) and as long as the outer circumference of the teeth is the same distance away from the line running through the mounting bolt holes, then the teeth will happily and merrily engage in the teeth on the flywheel. The different number of teeth is more than likely a result of the different motor configuration (number of poles basically) and compensates for the different speed of the motor.

So measure up the engagement depth of both gears relative to the mounting bolt line and see what you have. Given the well reputed interchangeability of RB starters, I would hazard a guess that you will find them to be the same.

[hardsteppa]

I Thought auto and manual starters were different, but not something i'd looked into that much to say for sure.

[GTSBoy]

I Thought auto and manual starters were different, but not something i'd looked into that much to say for sure.

If they are different, it doesn't matter. Nearly every auto-manual conversion has retained the auto starter that was originally on the engine.

[yoyo28gsi]

bump i have the same problem