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MG MGB Technical - CLUTCH PROBLEM ? - PLEASE CONFIRM

Hi everyone,

I was out for a cruise in my 72 B a couple of days ago when, in the middle of a gear change, I could not change up or down. Drifted to the side of the road but still could not change into any gear.

I turned off the engine and after a while I was able to engage all gears however when the engine was started again, no gears!

I was finally able to force it into 4th. and limped home in that gear, an experience in itself especially going around corners.

I've had a look under the hood, there are no fuid leaks and master cylinder is full.

The piston on the slave cylinder moves in and out as the clutch is depressed so hydraulics seem ok.

My uneducated guess is that the problem stems from the clucth and that the engine and tranny will have to come out for further inspection.

Would anyone like to confirm my worst fears?

Regards


Graham
GRAHAM HOYLE

Could be that the slave cylinder is not pushing
far enough to fully release the clutch.

You might want to have somebody press the clutch
pedal - and hold it down - while you measure the
travel of the slave cylinder push rod. It should
push out around 3/4" and stay steady (no drifting
back).

In anycase, before yanking things out, first try
bleeding the clutch hydraulic system.

On the next time when this happens, try pumping
the clutch pedal 2-3 times in order to build up
pressure in the system. It's not a cure - but it may
get you home under your own power.
Daniel Wong

It's very likely that the clutch disc or even the pressure plate failed. I once limped home with a clutch that wouldn't disengage, one of the springs came loose from the disc, and jammed between the flywheel and the pressure plate.
this was on the '74 Austin marina with the 'B' overdrive trans.
Pull 'er out, separate the trans. and see what you find.
let 'us' know.
Safety Fast
Dwight
Dwight McCullough

All good advice - but 3/4 inch Daniel? I have never got my pushrod to travel any more than 1/2 inch, and it's usually less. The clutch works fine.
Mike
Mike Howlett

Mike. I measured three cars with properly working clutch units. All three moved the rod about 3/8" (average of .362") and the clutches have continued to work for many years now. I agree with you. Les
Les Bengtson

Dwight,
Nice to hear I'm not the only one; I still have the disk out of my 74 1/2 GT that the spring worn its way through the steel and jammed between the disk and pressure plate.
Leland Bradley

I had a similar problem with my '69 GT, except it happened in my driveway. Couldn't engage a single gear, no resistance on the clutch pedal. It was like the clutch release spring was gone. Upon loosening the bleed screw on the hydraulics, I heard a creaking noise, which was the clutch finally returing to its engaged position. Bled the entire system out, never a problem since. Knock on wood.
D Gesse

It could be that your throwout bearing (or whatever the "proper" name for the cussed thing is) could be worn. I had that happen once and the symptoms sound very familiar. Couldn't engage any gear with the engine running but with it stopped the tranny shifted fine. I broke a synchro trying to drive it that way and had to tear down the transmission as well as service the clutch. That throwout bearing is a carbon ring that rides on a smooth metal insert held by the fingers in the pressure plate. They do wear down over time and once they reach a certain point the clutch will no longer disengage even though everything else seems normal.

Jim
Jim Blackwood

This thread was discussed between 03/10/2003 and 07/10/2003

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