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MG MGA - Rear End conversion

Anyone have experience replacing the original MGA rear end with an early MGB rear end and the lower ratio it provides? If so, how did it go and are you satisfied? Recommended?

Thanks,
Stephen
Stephen Lofaro

Hi Stephen,

Very common but the hand brake tag mounting is much shorter on the MGB. So people often cut one from their dead mga axel housing and re- attach it.

Cheers
Mark
Mark Hester

Oh, should anyone in the uk be interested, I have a sand blasted and re painted MGB banjo housing to sell, with long handbrake tag ready to weld on.

Contact me offline.

Thanks
Mark
Mark Hester

> Very common but the hand brake tag mounting is much
> shorter on the MGB. So people often cut one from their > dead mga axel housing and re- attach it.

It's probably easier to swap the MGB center section into the MGA axle housing. You may need to replace the spider gears in order to match splines with the axle shafts, but no welding is involved.

-Del
D Rawlins

The MGB center differential carrier is a direct change for the MGA carrier. Just swap the sun gears to have matching splines for the half shafts, a pretty easy job. A few hours to swap it over. See here: http://chicagolandmgclub.com/photos/a_diff

For MGA 1500/1600, a nice 10% reduction of engine speed, and nicer expressway cruising. For the MGA 1600-MK-II a 5% reduction of engine speed.

The 3.909:1 ratio (43/11) was a factory option for the MGA, but you will likely never find the matching speedometer to go with it.

Send the original odometer out to be re-geared to correct the odometer reading and to recalibrate the speed reading. Or you can (maybe) buy a 11/10 ratio change gearbox for the speedometer cable drive.

I've been driving my MGA with the MGB gears for 11+ years and almost 100K miles. Great swap for regular daily driving with some time on the expressways. I've been doing a lot of trailer towing with my slightly upgraded 1600 engine, and I like it.
Barney Gaylord

The swap to the MGB housing is usually done to get a correct length wire wheel axle when changing from discs.

Otherwise, as Del and Barney say, just change the differential and sun gears.
Neil MG

This thread was discussed between 31/01/2015 and 01/02/2015

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.