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MG Midget and Sprite Technical - Propshaft UJs

As mentioned in passing on another thread, I've recently acquired another MGB. Yeah, I know...

Anyway, it had a bit of vibration over 60MPH, which appears to have come from a worn propshaft.

I bought a pair of UJs from a well known classic car/MG specialist, via fleabay.

Having rebuilt the prop yesterday, and refitted it today, I decided to check the joints by hand before taking it for a test drive. One of the joints is moving about 1/16" from side to side, which is worse than it was before.

It's the same UJ - GUJ101 - as fitted to Spridgets.

Two questions:-

1. Has anyone else experienced a similar problem with a new UJ?

2. How to dismantle the joint without damaging it?

I've made a short video of it, although it's difficult to video with an i-phone, while lying on your back.

The movement can't be seen too clearly, but you can certainly hear it!
Dave O'Neill 2

are you sure its the uj and not the diff?

Yes, the movement is in the joint at the rear of the main tube.
Dave O'Neill 2

This is where the movement is...

Dave O'Neill 2

what is the gap in the prop compared with the gap in the diff side of the yoke?

Yes Dave the EXACT same thing happened to me on one of my Fords about 30 years ago.

I fitted the new spider and bearings which all came in a kit and it was terrible. Worse than before I did it.

So I took it all apart and found that two of the new bearings were the correct type and the other two were far too loose a fit on the spider journals. By pure chance the two slack ones were in the same plane.

I suppose I should have noticed, but I did the swap lying on my back in the snow and just wanted to get it over with.

Not saying this is what's happened to yours, but something is not right. You definitely should not have that sort of movement in the assembly. You shouldn't have any discernible movement in a new joint IMO. Is it possible the jaw clearance in the shaft side of the UJ has opened up somehow? I doubt it but it's easy to measure.

As to dismantling it without damage, I don't know. When I did it I wrecked the bearings getting it apart and just bought new ones, but not from Ford. I got equivalent bearings quite cheaply from Grampian Bearings in Dyce.

Dave, our local propshaft reconditioner has been known to mutter and shake his head about UJ quality and this problem and the need to sort it by shimming between circlip and cup.
Paul Walbran


Thanks for the confirmation.

Having not measured everything before assembly, it will be difficult to know whether to shim one side or both, so as not to unbalance it.
Dave O'Neill 2

Just by chance did your new u/joint kit come with a surplus of circlips
Not saying this is the problem but over here a lot of u/joints come with a couple of different thicknesses of circlips for different applications
Were there some thicker ones in your kit ??
William Revit


No, only four circlips per joint.

Thicker clips wouldn't work, as they wouldn't fit into the grooves.

An extra circlip may well do as a shim, though.
Dave O'Neill 2

This thread was discussed between 28/06/2015 and 29/06/2015

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