Dynamo pulley

[Gazzer]

Hi can any tell if the 998 cooper has a different dynamo pulley to standard vehicles dynamo’s.
I’ve seen a “cooper pulley” in restoration catalogs is this a DIY mod or Factory specification?

[Allen Brzeczek]

I am fairly certain that a larger dynamo pulley was fitted as standard to the the Cooper S to reduce revs on the dynamo presumably on the assumption that the S would be enjoyed and driven somewhat more enthusiastically.

Not sure if this this was fitted to the Cooper.

[twc641]

What is the diameter of the two pulleys?

[Classic1]

Cooper s pulley is 92mm.
3 5/8 dynamo has thicker mountings on pulley end

[twc641]

diameter of a cooper?