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MG Midget and Sprite Technical - Diff and axle case

Hello,
Is it possile to fit the diff from a frog in an axlecasing of a 1275cc, without mods?
laurent
ld derancourt

should be no problem, that is, if you want the 4.22 gear ratio that the frog came with

the 1275s came with a 3.9 diff (better for cruising)


The axle housing is the same. To answer your question.
Norm
Norm Kerr

Early 1275 had 4.22, agree it is a bit low for normal running in a 1275.

Richard.
richard boobier

Thanks Norm,
I think I have to keep the frog halfshaft too to suit the diff.
I have a midget MKI with a very poor body to transform in a fastback coupé. I also have a very good 1275 body shell, So I ask myself the make the coupé with the 1275 shell and the parts of the midget MKI.
But I have to put a rear train of a 1275, but keep the 4.22 Diff.
The shell will be modify to suit the fasback GRP part and to accept the frog windscreen and frog doors.
Certainly not a difficult job, as the car will not return to opentop version, so no need to adapt the B post or rear bulkhead to the MKI shape.
laurent
ld derancourt

I always thought my Frogeye had the 4.5 diff. My Mk II Midget has a 4.2 diff.
Neil (K series)

FYI:

'78 ~ '80 Midgets came with 3.77 ratio (8/'77, from GAN6-200001), better for highway use than the 3.9 used from 12/'68 ~ '77 (but the 3.77s are rare, so more expensive). "58 ~ '68 (948 and 1098cc) used 4.22.
When in doubt about what you've got, the ratio is stamped on the outer edge of the diff housing (and, if it is off the axle, an additional stamp is visible inside as well).
Norm Kerr

Check the ratio in the 1275 up until Dec '68 they were 4.22 also.

Yes they swop O.K I changed my 1275 4.22 for a 3.9 years ago.

1275 shafts are stronger than the earlier ones.

R.
richard boobier

This thread was discussed between 30/04/2010 and 01/05/2010

MG Midget and Sprite Technical index

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