Getting Starter Motor pinion size and diameter right

It can get confusing when looking for different starter motors, but it is important to get the pinion size and diameter correct for your vehicle.

What is the question?

There is quite often confusion over whether an 8 tooth Starter can replace a 9 tooth starter, or vice versa, with the 8 tooth being the original size for the vehicle. Questions like this also apply to different diameter drives as well.

Why does it matter?

Most starters have the Drive or Pinion in the centre of the Drive End Housing. This is also particularly the case with Direct Drive Starters where the armature is through the centre of the starter. It is possible, though, to manufacture the Drive End Housing with an offset so that the Drive is not in the centre of the housing.

What’s the explanation?

A Starter that has a different diameter and/or number of teeth can still work in place of the original. For example, there are examples which have either 11, 12, or 14 teeth versions. Each of these versions will work on the same vehicle, however, you cannot interchange pinions onto different starters with a different number of teeth, as the offset diameter is different.

For example: