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MG MGB Technical - Driveshaft for LD overdrive + Mk 1


Which driveshaft would be suitable for a Mk 1 and an LH overdrive?

Apart from installing engine plus gearbox and measuring, can anyone offer advice?

Thanks
Mark Thompson

The parts list says you'll have a 31 1/8 inch prop (3 synch/od/banjo axle).

Apparently all 4 synch props are the same size too.
Seems odd to me, I would assume an OD prop to be different to a non OD. But that's what the parts book says!
RoadWarrior

4-synch OD and non-OD gearboxes are half an inch different and only ever fitted with Salisbury axles, so there is only one prop-shaft. 3-synch OD are about an inch shorter than non-OD going by the prop-shaft length, and were mated with both banjo and Salisbury axles which were also of different lengths, nose-wise - banjo longer again going by the prop-shaft length. The four possible combinations used three different lengths of prop-shaft, 3-synch OD banjo using the same prop-shaft as 3-synch non-OD Salisbury, which is the same as both 4-synch Salisbury prop-shafts. So it depends on whether you have a banjo or a Salisbury axle - Mk1 GTs all had Salisbury whereas late roadsters could have either. With a Salisbury the same prop-shaft should fit i.e. 31.125, but with a banjo you will need the shorter 30". All these are fitted lengths. But then again as the factory never mated a 4-synch with a banjo in a Mk1 body you'll have to install the engine and gearbox and then measure to double-check, as the engine mounting points are the prime datum for the position of the gearbox drive flange.
PaulH Solihull

Mark

Just find the length from prop flange to face for back plate of a 3 synchro overdrive gearbox.

compare it with the length of your LH box then either add or minus the difference from the 31 1/8 inch prop that is correct for the factory car.

this will give you the length you need then you can find a suitable prop for that length.

Ste
Ste Brown

I have a '67 that has a banjo rear axle and a 4 synchro/OD transmission fitted at present. I'm using the 30" drive shaft. RAY
rjm RAY

This thread was discussed on 27/10/2011

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