Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Diff problems?

I drove the car into the garage two days ago and left it, as usual, in gear with the handbrake off.
When I came to move it this morning it was locked up as though I had left the handbrake on.
Jacked up the car and, with both wheels off the ground, found the offside rear wheel was locked (out of gear). However what was slightly disconcerting was that there was a slight rotational rock on the wheel (a few mm). My first thoughts had been a jammed brake cylinder but would there still be this rock? When I applied the handbrake there was a solid lock up.
I removed the wheel and then the nuts holding the drum (wire wheels!) and found I could pull the drum forward slightly and then the shoes gripped the edge of the drum. Unfortunately because I couldn't turn the wheel I couldn't get to the brake adjuster.
Wondering what to do next I went over to the other rear wheel and spun it over. I then found the problem wheel was free.
My worry that there is something happening within the diff because a seized cylinder doesn't seem to fit the bill. I would appreciate everyone's thoughts.
Graeme Williams

Is it possible that the hub nut has come loose? Or perhaps there is excess play in the hub? Either way might cause either a twist or outboard movement in the hub causing the drum to bind. One you removed the drum nuts everything was loose allowing spinning the other side to cause it to pop back into alignment?

Just thinking out loud really, but sounds like something along these lines is a possibility. And if it could be the hub nut then it needs to be checked pdq.
Neil MG

Thanks for the thought Neil. It was all tight axially. I could only pull the drum forward when the nuts were undone.
Graeme Williams

Possibly the cross shaft has dropped out because the pin has sheared. It has happened to me in my TC race car (with spridget diff). Symptoms would be that the wheels will turn in opposite directions when jacked up but the diff/tailshaft will only turn a fraction of a turn ..... although jiggling in the right direction might get it turning. See details on Spridget thread.

Bob Schapel
R L Schapel

Thanks Bob. Replied in Spridget forum.
Graeme Williams

Gentlemen: a bit of off-the-wall thinking!

I am sort of convinced my lockup is a diff problem. It would be nice it it were something outboard. The nagging thought I have in the back of my mind is this -

I have not had an issue with the rear wheel locking solid before.
I have only pressure washed the wire wheels on the car once and that was just before I ran it into the garage and left it for two days to then discover the locked rear wheel.

I cannot see a link between the two incidents but it is a little odd. The drum will have got water inside I can now see happening because the adjusting hole in the drum would have been open to the spray (not good!)
the locked wheel had a little (+/- 5mm at rim) movement at the tyre and I could pull the drum towards me a little before the inner raised edge caught the edge of the shoe.

Any ideas whether the inadvisable (now) pressure washing could have caused it and how?
(and it didn't get the grease of the wheel!)
Graeme Williams

Jack the car with both rear wheels up. Release hand brake, and select neutral at the gearbox. If the one wheel is still locked, try turning the other wheel. If other wheel turns, and the propshaft turns at half speed, then it is not a differential problem. This leaves locked up brake on one wheel, which should be easier to fix than a differential.

If one wheel turns forward while other wheel turns backward, then no locked brakes. If propshaft turns some, but then hits a dead stop in either direction then it wold be a slipped pinion shaft in the differential needs to come out for repair.

This is not a daunting job. Drain differential. Disconnect propshaft flange from differential. Pull both half shafts out a few inches. Then remove about ten nuts,and pull the differential carrier assembly out the front.
Barney Gaylord

Agree it's not difficult but I'd rather not have to do it and go through the whole rigmarole of getting the seals on the halfshafts oil tight again. Done it three times before but on a smaller vehicle.
The diagnostic problem is that the wheel suddenly freed itself and has not locked up again.
Graeme Williams


Brake area inspected by two of us - nothing to explain problem
Hub bearing ditto
Diff removed; inspected with microprecision. Nowt!

Putting it back and forgetting about it.
Graeme Williams

You may have a "Gremlin" ... Let loose some Lucas smoke and chant... OUT, Mowagaliese while having a pint of Speckeled Hen.

works for me ;-)
C.R. Tyrell

This thread was discussed between 27/05/2016 and 14/06/2016

MG MGA index

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