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MG MGA - Dropping the Diff

As far as Sprites have been concerned, I have been able to drop the diff with the back axle in place by working flat on the floor underneath and man-handling the diff in and out. Getting it back was always a bit tricky as lifting and lining it up was a fit fiddly.
I now need to do the same job on the A. I have concerns that the diff may be somewhat heavier. Has anyone done it this way? Can anyone tell me how much the diff weighs as at least I can then compare it with the Sprite diff.
Obviously I don't want to pull the diff and then find the weight pins me to the garage floor!
I would remove the axle but not as first choice as it would mean having to bleed the brakes.
Graeme Williams

Graeme

I did mine single handed. I don't recall any undue problem. I might have put a trolley jack underneath to take the brunt of the weight as I pulled it forward, but I cannot remember. Alternatively I guess you could put a few block of wood underneath so that it does not drop too far.

Steve
Steve Gyles

Graeme,

I'm 71 years old and I just swapped a 4.1 for a 3.9 a month or so ago, working from underneath. I had it on jackstands as high as I could get it (maybe 12 - 15") and had no problems - it's not that heavy...maybe 20 lbs? After the swap I had to go back under and replace the front oil seal that was leaking - again, not too hard but I recommend you take care of that when the differential is on the bench.

Gene
Gene Gillam

Graeme. Just weighed my 3.9 (awaiting labour) and the rough figure was 32 pounds. 70 next week and managed to lift it to read the hanging scales. Should be no problem: I changed a Morris 1000 gearbox lying underneath easily enough. Shane
Shanerj

Damn, stronger than I thought I was...didn't know it was that heavy or I'd have gotten my son to help.
Gene Gillam

Graeme

Gene's mention of the oil seal reminds me that I made up a useful tool if you choose to do an oil seal change on the bench. It holds the flange steady while you undo/torque up the nut.

Steve

Steve Gyles

Great! Thanks for the experiences. I have done it several times on the Sprite and it is less involved than removing the whole back axle. It was just the weight that worried me.
I hope I don't get into pinion seals. I have not read up on this topic (hope I don't need to) but on the sprite there is preloading and a collapsible spacer to take into account. I suspect the A may be the same.
Graeme Williams

Graeme,

The MGA has shims (items 29 and 33 in the attached image).
It does not use a collapsible spacer as in Triumph differentials.

Mick

M F Anderson

Graeme,

All I did when I changed out the seal was pry the old one out, tap in the new one and bolt it back up. No new noise and no drips.

Gene
Gene Gillam

I am intending to stay well away from the input end of the diff. At least, I hope so, depending on what caused the lock up.
Graeme Williams

What a horrendous job this turned out to be. Despite all the best advice given here we found it very difficult to pull the diff off the mounting studs (and yes we had pulled the half shafts!).
The one thing we didn't realise (because working in the back axle area on an A is new to me!) is that life gets much easier if you remove the battery cover. That was a breakthrough and it was what made the job possible (but not a doddle). The prop shaft bolts were incredibly tight and two of them were so imoveable that working, as we were initially from underneath meant we couldn't get them undone. They were also Whitworth - is that right?

So the biggest lesson which I am sure everyone else knows is REMOVE THE BL**DY BATTERY COVER! Doh!

(Nothing wrong with the diff by the way; or the brake)
Graeme Williams

This thread was discussed between 03/06/2016 and 09/06/2016

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