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MG MGB Technical - Driveshaft flange mismatch?

When picking up my 70 mgb roadster project car, found driveshaft bolted on backwards (yoke sleeve at rear) and the u-joint at other end was totally shot. I noted that the yoke sleeve flange was different than the rear flange in that was not circular but scalloped - but otherwise the bolt holes lined up ok. After fixing and reinstalling shaft properly, found flange on yoke sleeve was not flush with gearbox flange because it would not entirely fit over the gearbox nut - which was fully on and tabbed over by the lockwasher. Is the flange the wrong part or is the nut not on properly?
Rod Dehner

Sounds like the wrong part to me- you should be able to source a good used front flange.
J Delk

Sounds like a late propshaft and an early gearbox.
On my '77, (LH overdrive) the nut is wholely within the flange, and doesn't stick out. (The front end wasn't round IIRR.)
The manual shows a section through the type "D" overdrive with the nut clearly proud of the flange.

As above, you may be able to change the flange, or turn a spacer ring, but be carefull that the splined part has enough movement if you do add a ring.
Martin Layton

Rod. Your car should have the later model drive shaft/prop shaft, that was used on all of the Mark II and later cars. These were the same length for the OD and non-OD cars, as opposed to the earlier, Mark I cars, which used different lengths.

With the Mark II onwards cars, the front and rear flanges are circular and the hole pattern only allows them to fit one way or at 180 degrees, but not at 90 and 270 degrees. In other words, the hole pattern is not evenly spaced.

In your case, your description does not equate to the factory set up. Good, used prop shafts are relatively inexpensive. I would replace your existing unit, of unknown origin, with a factory unit. That way, you know you have the correct parts installed. My friends, Bob and Gil Schaulin, have a rather large MG wrecking yard and can supply you with a good, used prop shaft with new U joints installed (should you desire--I always have problems installing them myself and let Bob do it for me). Their e-mail address is and their telephone number is 602-415-1846. Should you contact them, mention my name.

Les Bengtson

Thanks all. Sounds like changing the driveshaft is the surest route to take with this car of many mod's over the years.
Rod Dehner

This thread was discussed between 29/09/2006 and 02/10/2006

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