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MG Midget and Sprite Technical - Diff and clutch

Hello All,

I'm a long time lurker and very occasional poster here, looking for advice. My car is a '75 1500. I'll tell you the whole story...

A few weeks ago my engine died spectacularly (con rod poking through the bottom of the sump. My local garage, who I generally hold in very high regard, and who I have been using for many years on a variety of cars, fitted a reconditioned engine, and put in a new clutch at the same time.

Within the first few miles I noticed a very faint intermittent noise in 4th gear when accelerating. It was one of those noises that, at first, you're not sure whether you are imagining it. Sounded a bit like an exhaust or manifold just starting to blow a tiny bit, a sort of put-put-put-put.

Over the next 20 miles or so, it got progressively worse, and spread to 3rd gear as well. So I decided to drive back to the garage for them to take a look.

On the way there, the clutch completely failed, and there was a horrible clunking/grinding noise. I had to get recovered from the roadside to the garage.

Their diagnosis is that two things have happened - the clutch slave cylinder has failed, and the diff has broken up internally ('when he took the plug out, lots of little pits came out of it'). It is their view that this is mere coincidence, and nothing to do with the fact that the engine and clutch were replaced 33 miles previously.

Can any of your learned brains spot what could have been done during the engine/clutch replacement that might have led/contributed to the failure of the slave cylinder and implosion of the diff, or was it coincidence as they say?


K Williams

I cant think why the garage would have needed to look at the diff with the re con engine and clutch job you mention. So to me that gets them out of that problem, the Clutch however is another matter altogether.

The gearbox and the whining you mention, have they drained the gearbox and reported if they have found anything in the oil ?

I don't know the 1500 model so well but cant think why a failing slave cylinder would contribute to the problems you encountered, to me it either allows you to engage and dis-engage the gearbox or not.

Does the engine idle ok ? are you able to select any gears at all ? when you made it to the roadside where you in gear ? or stalled and coasted to a stop ?
P Bentley

How do you know the "clunking/grinding noise" was coming from the diff?

How do you know the bits of metal in the oil from the diff, weren't there from a previously failed h/shaft, that wasn't fully cleaned out?

I'd stop them from pulling your diff, until I knew for certain that the diff is actually causing a problem.

Concentrate on the g/box.

If there was something wrong with the way they fitted the clutch centre plate, that may have put strain on the 1st motion(input) shaft, which may have caused the gradual symptoms in the g/box, which eventually led to failure.

Could you prove it? I doubt it. Try an AA inspection if you are a member and can get it free.

Frankly I just don't trust garages. Never have.

Today I passed by my local garage, and they had an RWA k reg midget on blocks in the four corners. Nothing wrong with that, EXCEPT, that the blocks were under the floors at the front and rear corners, not under the rear spring plates or the chassis rails at the front. And this is a garage with a good reputation too.

Lawrence Slater

when the engine blew with the rod out the side it will have put sufficient shock load down the drivetrain to cause a failure in the diff. Probably a couple of root cracks in the sun or planet wheels, which have rapidly worsened to the point where one or more teeth broke free and wrecked the rest of it.
The clutch slave is prone to fail after fitting a new clutch assembly as it has to cope with a stonger release pressure (new pressure plate vs. worn)
David Smith

Also, after fitting a new clutch assembly, the slave cylinder piston will be further down the bore, towards the rusty end.
Dave O'Neill2

Thanks for all of the responses.

To answer some of the questions:

The engine idles OK;

I got it into gear, where it remained briefly before stalling with the nasty crunching noise (which was from behind me), I then took it out of gear and coasted (down hill, in rush hour traffic);

The clutch was then dropping straight to the floor, so I didn't attempt to select any more gears once I was by the roadside;

As an additional point, there was a quiet (but ominous) rumbling noise from the back end when I was being towed, which could be consistent with something nasty going on with the diff.

Sigh :/
K Williams

This thread was discussed between 12/05/2014 and 13/05/2014

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