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MG Midget and Sprite Technical - Clutch woes

Hi,

A while back while driving I hit a pot hole at the end of a hill in about 60mph, quite a hard bump and my car setup is hard fast road suspension.

Directly after that my clutch stopped working, the pedal is sloppy and hanging almost all the way to the bottom, so almost no travel in the pedal. After a stop and a quick visual I decided to try and drive it home instead of getting towed. I managed to drive the one hour drive back home. Gear changing up and down between 3-5 was no problems, but up and down between 1-2 and also reverse was troublesome as the clutch didn't disengage properly.

At traffic lights I had to put the gearbox in neutral, because if I had the pedal pressed down and stopped, after a while the car started pulling as if realeasing the pedal even if I didn't.

Back at the garage my mood was quite ***** so all i did was another visual, no visible leaks, still brake fluid in the reservoir.

Car is a MK1 sprite, concentric clutch slave cylinder, 7,5inch clutch, original dual MC sleeved to 3/4 bore due to my front disc brake setup, original flywheel machined and lightened.

Now I'm thinking as to what approach to make. Instinctively i'm thinking that something in the MC has failed, like the returspring for the piston or should i look elsewhere first?

Regards
Alex
Alexander Sorby Wigstrom

Clevis pin dropped out?
Peter Blockley

Could be the spring in the m/c or sticking piston
You could try sitting in the car and rapidly pumping the clutch for say 10 pumps and see if it improves, it might just have a bit of rubbish in the cylinder that got dislodged

William Revit

Think you'll be unlucky if it's the master cylinder.
As it happened after hitting a pot hole it's more likely something's dropped out as Peter says or has been bent/damaged, I'd have thought.
Best get it jacked up and have a good look underneath for anything which seems amiss.
If you don't see anything obvious, take a couple of photos and post them here - there are a lot of eagle eyed people on this forum!
Is it a 5 speed Sierra gearbox?
Jeremy MkIII

You say "concentric clutch slave cylinder" - as in inside the bellhousing?
AdrianR

Correct Adrian, so clevis pin and something underneath is ruled out.

I still haven't goten around to make an effort, but I probably will, maybe next week..

Alexander Sorby Wigstrom

Clevis pin in the pedal box isn't ruled out is it?
If that pin has dropped out the lever will still act against the yolk of the pushrod but movement will be much reduced and the clutch won't fully disengage.
GuyW

Guy, You mean the one connecting the pushrod fork to the pedal?
Didn't even think about that, as it's underneath the pedal spring it didn't cross my mind too check, will do when in the garage next time.
Alexander Sorby Wigstrom

Yes that's the one I meant. It seems unlikely that it would come out from there, but if it did it would give something very like the symptoms that you have. And the best bit - it would be an easy fix !
GuyW

Would be nice if that's all it is, fingers crossed!

I don't like concentric slave cylinders. I've had two fail on different cars, both then meant gearbox out jobs (one DIY, one by garage) and the 2nd managed to contaminate the clutch plate as well.
AdrianR

Update,

The pushrod-fork clevis pin was in place as expected.

There was a significant pool underneath the car but appears to be engine oil, unless it's a mix of hydraulic fluid and engine oil? The car usually leave small traces of oil but this was more than usual.

I removed the dust cover around the pushrod on the clutch side and the inside was covered with break fluid. So I removed the MC and stripped it down, when I removed the cover for the pistons and springs, the break side popped right out but the clutch side didn't. So I pushed the piston up and down a few times and felt that something was a bit off. Once out the piston is straight and without marks or damage, as is the spring. The upper seal is without apparent damage but has obviously let fluid pass. My thesis is one of the following

1. Either the upper seal has somehow fold or caught on the piston or inside the cylinder.
2. The pressure reducer attached to the spring on the bottom/inner side didn't come out with the spring, so the spring or plastic reducer could somehow have got caught in an off position making the travel of the piston inert.
3. The cylinder is oval, catching the piston or just letting fluid pass all the seals which is causing my pedal to act up.
4. The failing seal is alone the only culprit.

/Alex
Alexander Sorby Wigstrom

Solved,

I put new seals in the MC, bleed clutch, brakes and everything works fine now.

Alexander Sorby Wigstrom

Well done.

The pothole was just a separate unrelated event then.event then.
Nigel Atkins

This thread was discussed between 21/07/2018 and 06/08/2018

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