yep found it 22G1128

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1971 mk2 police cooper s
1988 rover mayfair modified!!

OK, it will be either a 22G1128 or a 22G846. To be sure does it have Synchro on 1st?

This will fit straight on to your A+ 1275. If you have a 1275 engine (eg Cooper S Engine) on it now, use the primary gear from that engine, not the A+ one. The teeth are different.

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yes it does have synchro on 1st.
i think i'll just do a straight swap, instead of gutting the recon rod change to put in the remote. (seems like too much hassle)
can the cooper s diff handle 100bhp or would you recommend upgrading it, i have a cross pin diff sitting on the rod change box ??

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1971 mk2 police cooper s
1988 rover mayfair modified!!

Depends on what you have in mind for it's use. Eg, street car, racer, motorcross, kana etc....

The standard diff in good order with a good quality diff pin and sun gears will take 100 HP OK but avoid spinning too often and with too many revs on.

If you envisage spinning a lot, use a 4 pin or quaiff diff.

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so the cross pin diff in the rod change housing can be put in the remote housing?
is this something i would need to pay someone to do?
or could a backyard mechanic do it? (aka me, limited ability, but can normally work most things out)

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1971 mk2 police cooper s
1988 rover mayfair modified!!

Yes, the cross pin diff should go in the remote box OK. You should be able to swap them over yourself. I would recommend at this point that you get your hands on a workshop manual. It's not that difficult, but the manual does have fairly good step by step instructions.

Does both gearboxes have the same diff ratio? If so, just check that the gears have the same tooth design as there is early and very late types, not interchangable.

If the ratios are different or early / late crown wheel and pinion types, you will have to change the crown wheel. Again not difficult.

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im pretty sure the same diff ratios
i know the new one is 3.44 and im pretty sure mk2 cooper s were also 3.44
i've got the black comprehensive workshop manual, gregory's and haynes
so i'll be taking it slow reading all 3 as i go
thanks for all your help gt mowog

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1971 mk2 police cooper s
1988 rover mayfair modified!!

Yes, standard Cooper S Diff is 3.44, just be sure to check they are the same tooth patern / type.

Your welcome, have fun doing your project

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