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MG MGA - Diff as Jacking point

Does anyone know if its possible to use the rear diff as a jacking point ? I have seen mechanics use the differential as a jacking point. I'd thought I'd ask for advice here before trying it.
DJ Joy

Used it many times.

Steve
Steve Gyles

Mr Joy. Indeed garage mechanics will routinely use the diff as a convenient rear jacking point and it doesn't appear to cause a problem that I know of. However, I hate it and avoid doing so as it seems to me wrong from an engineering point of view to apply such leverage to the back axle assembly. No doubt the axle casing is a substantial piece of metal but it offends my engineering principles! Probably misguided and will no doubt be corrected by others but that's my take on the subject!
Bruce.
Bruce Mayo

Always use the diff, and have done for 25 years. I use a jack with a rubber pad in the saddle.
dominic clancy

I have never thought of using it so you can always learn something new. I suppose I would previously have always have taken Bruce's view.

Paul
Paul Dean

There are plenty of forums on the web where the same question has been asked. Most of the concerns are where the diff housing is an alloy or where there are thin (tin plate) covers. Like Dominic, I have frequently jacked the car on the diff when I specifically want both wheels off the ground at the same time. Other than that I use the jacking points recommended in the Workshop Manual, which brings me on to a query. The manual states in Section O.1: "The car must not be jacked under the frame side-members".

What do they mean by 'frame'? Are they referring to the body sills? I would have taken frame to mean chassis, but I think not in this case.

Steve
Steve Gyles

I also use the diff as a jacking point as a matter of course and have never had a problem.

Steve, It is strange, but I guess you are right and that it means the body sills. Certainly no problem at all jacking anywhere on the chassis side-members. Unless, perhaps, that comment just relates to the factory supplied jack in which case it might be a safety issue.
Neil MG

Also used the diff many times as a jacking point, with a bunched up rag in the jack saddle. No ill effects as far as I can tell.
George G.

Had a friend, a newby MGA owner, jack up his car with a single small headed jack under the side frame near the middle of the door. Result was a loud bang and a kink in the frame!

Peter.
P. Tilbury

I would suggest that a car where the chassis rail experiences a failure when being used as a jacking point needs to be very carefully checked for structural rust issues. I would never use the original jack for anything serious, its base it too small to be safe for anything except changing a wheel, and then it should be used under the suspension point for the wheel in question.

The important thing with any jacking activity is to be sure that the jacking point is solid, and that everything it attaches to is also solid - that is why I hate working on cars that are really dirty underneath and always pressure wash the visiting ones if I can.
dominic clancy

This thread was discussed between 11/12/2014 and 15/12/2014

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