Are starter motors interchangeable?

[bmw9818]

M40 starter to m20 ?

Wiring is all the same no?

[sean_318i]

The ring gear is different on these flywheels so the starter has a different pitch on the teeth. If you use a m20 starter it will jam.
The m42, m50 and m52 will work though or you could use an m20 flywheel and clutch with the m20 starter but thats not really worth the effort.

Seán

[sean_318i]

Sorry read the question wrong but answer is still the same m20 flywheel needs m20 starter.

Seán

[bmw9818]

nice one cheers