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MG MGB Technical - 79 MGB Clutch Problem

I have a problem with the clutch on my '79B. It has 95,000 miles on it. Recently the engine has started racing in high gear going up hills. However the car will easily die if I try to kill it by letting the clutch out at a stop. There is a very slight leak in the clutch system that I can't find. Talking on the order of two drops in two weeks at the clutch master cylinder.

Before I pull the engine to replace the clutch is there a possibility of the clutch hydraulic system holding the clutch partially engaged rather than fully engaged?



Possible.I have seen clutch slaves with a stout return spring, maybe because of such a problem. Worth a try!
Allan Reeling

The fact that that the engine increases in rpms, when going up a hill, would indicate a worn clutch plate. Does the clutch slip in the lower gears? I have a customer's '72 GT here that does the same thing. He thought that it was a problem with the engine. I told him no, the clutch is worn out. After servicing the car last year and taking it out for a test drive, I noticed the rise in engine rpms, in top gear, while the speedometer remained steady. It only occurred in fourth gear. RAY
rjm RAY

take the opportunity to look at the hydraulics too, replace the fluid, check master, slave, hose, etc., etc.
Nigel Atkins

Thanks for your replies. I figured I needed to pull the engine to replace the clutch but I was hoping against hope that I would be able to find an excuse not to. This will be a winter project.


Two drops in two weeks is nothing, as the friction plate and the release bearing wear they will cause the fluid level in the master to drop as the spring in the slave that Allen mentions is pushing the slave piston out all the time to take up any wear at that end of the system, which pulls down fluid from the master.

As said slipping in 4th, particularly if it happens going up hills where the throttle will presumably be further down to maintain a given speed, is a classic symptom of a worn friction plate, but can also indicate a broken diaphragm spring. Which doesn't really matter, as you should be replacing with a clutch kit that contains cover plate as well as friction plate and release bearing. Don't leave it too long or the rivets in the friction plate can score the flywheel, meaning that has to be removed to be refaced.
Paul Hunt

This thread was discussed between 10/10/2014 and 11/10/2014

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