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MG MGB Technical - Clutch cover life

I have the engine out of my ´63 MGB, and of course I take the opportunity to have a close look at the clutch. It has been in the car for about 14 years, and about 50.000 kilometers.

The clutch plate is only about 20 % worn, and the surfaces on both the clutch cover and flywheel are even, nice and shiny. But some of my MG friends say that I should change the clutch cover anyway, because after all these years the spring will have lost some of its tension.

Sounds sensible to me. What do you think?



Tore

How did you measure and calculate the 20%? Are the springs in the centre of friction disk loose? A good clutch specialist can test cover plate spring pressure. If in doubt change so the you wont have go back for another 50k. Check pivot arm pin and bush also.
Mike
Mike Ellsmore

The general opinion is change the lot, the pressure plate, friction plate, release bearing, plus the spigot bush. Has Mike said you don't want to repeat the process anytime soon!
Allan Reeling

Tore,
Clutch life should be at least 120K Km but things can go wrong and most of us would take an easy opportunity to change - as Mike says "if in doubt - change".
Roger
Roger W

Tore. I was the original owner of a 79B which had about 62K miles (about 100,000 Km) and the clutch was still fine. My daughter's car was purchased used, but came with a large stack of maintenance records. The engine was pulled at 96K miles due to a bad valve. The clutch, believed to be factory, was still in good condition and could have been used for 10K miles or more. Properly used, the clutch will last for quite a long time, far longer than the 50,000 Km (about 30K miles) that you note is on yours. The biggest problem with the system is not the clutch but the throwout bearing which is of the graphite type and tends to wear when the clutch is depressed excessively (e.g. holding the clutch pedal depressed when at a traffic light or stop sign). If the throw out bearing shows signs of wear, I would consider replacing it while you have the engine and transmission apart.

Why not replace the clutch as a precaution? You have a known good system which has been working fine and seems to be in good condition based on your visual inspection. How many "modern" parts have we installed, "as a precaution", and found to be of lower quality than the parts they replaced? How many "new parts" have we installed that did not last a fraction of the use life of the original parts? Now, if the parts seem to be in good condition I leave then in place, or reuse them, rather than put some part of unknown quality in as a precaution.

Les
Les Bengtson

I totally agree with Les.
Dave O'Neill2

Thanks, everybody. After all your comments I probably will re-install the old clutch, and only replace the throwout bearing. Not because it is worn, but it is of the type where a rolled pin holds the carbon in place, and I know there has been a lot of trouble with this. The throwout bearing was renewed 5 years ago, when I had to take out the engine to renew the starter ring gear on the flywheel.

The old clutch is Borg & Beck, the spare I have is made by Powertune, and I am not sure if I trust it.

But first I will measure the wear on the clutch plate more precisely. The important thing is the height of the segments, right?

Tore
Tore

The cover plate is probably the longest lasting item of the three. However having gone that far and with 50k even kilometers I'd change the lot. Only for a B&B though. Then again, at that rate of miles you could probably go another 15 to 20 years before that friction plate needs replacing.

You are right to change the pinned release bearing, in fact I'm surprised it's still working given the problems there have been with these.
Paul Hunt

I'd stick with the old original cover, it works properly with no problems. Aftermarket ones can have problems - spring gets lop-sided and balance not as good. We had a 64 MGB in recently which was in for its first engine overhaul after a respectable 140 000 miles. It had previously been fitted with an aftermarket clutch cover (not by us), which the balancer reported was seriously out of balance. My money's on a link between that and the crack in the rear main bearing.

But do replace that "pin" bearing!
Paul Walbran

This thread was discussed between 26/03/2014 and 28/03/2014

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