How do you identify a Cooper S diff? and any diff ratio?



psssstttt....Aaron...can you help identify a few bits and pieces on Saturday if you decide to help us move the S's ?

I don't know what is Cooper S / 1275 or just standard. I have identified the Cooper S gearbox side covers (4 off) and 1275 pushrods....but there is a TON of gears and a few diffs and other stuff that we need help with....

It'll have more teeth on the crown wheel than a standard diff.
Not sure how many though.

the difference in an s diff is mainly to do with it's output shafts rather than the crown wheel and pinion.
With geaboxes, the laygear has 1 tooth less than a std unit, 27 if i can recall off the top off my head. S boxes were just a close ratio box in the top end.
Kevin will confirm though later on i am sure.

Cheers

Aaron

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The thickness of them?

yep

Cheers

Aaron

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The diff ratio is marked on the side of the crown wheel on the bolt head/bearing side. It gives the number of teeth on the crown wheel and the matching pinion. S is 18/62 to give 3.44:1. The crown wheel is part No 22A411.
Just to make matters more confusing the 3.65:1 ratio also uses a 62 tooth crown wheel but it mates to a 17 tooth pinion.
Counting the number of crown wheel teeth is not enough. You must check the mating pinion number of teeth as well.
Early S diffs (approx first 600 or so OZ cars) used rubber inner unis and are no different to an 850. These have the drive flange held on by a nut. Later S diffs used the Hardy Spicer output shafts which have the drive flange held on by a bolt. They just happen to be the same as those used on auto boxes.

Regards
RonR

cheers Ron

Mk1 S had much higher 1st & 2nd gear than a Deluxe did. And less gap 2-3.

On a Mk2 S box the input gear (1st motion shaft) has 18T not 17, and the cluster gear it uses (22G1040) is smaller diameter on its mating gear to compensate. But has the same tooth count...!
Physically the 1st, 2nd and 3rd gears are the same parts as a K or A series rodchange box.
What this means is the cluster runs 1/17 faster, so there is less gap between 3rd & 4th but the gap between 1-2 and 2-3 is the same as a Mini K or common Clubby.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

see i told you kev would tell you exactly.

Cheers

Aaron

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hmmmm....yes.....