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MG MGB Technical - no clutch

Had a great day today, spent ages wandering around the NEC at the classic car show.

My '77 BGT ran great, I got home and looked at all of the bits that I had bought,and added up the cost.

Anyway, I went for a short drive to my parents, 2 miles down the road, I slowed for a roundabout, the car stalled. Some idiot behind in a new fiesta, drove right up behind and wasn't happy that I had stopped!

The BGT started fine, but the clutch pedal was on the floor! it came up again slowly. I couldn't select any gears, so I started the engine with the car in 2nd gear and managed to get home and put it on the drive.

Im guessing master or slave cylinder?

Any easy way to tell which without lying on the floor on this cold/wet night?

Also any tips on fitting these?

Thanks
John
John Collins

Check the obvious first and see if there's and fluid in the reservoir. Then I guess the next thing is to inspect the hoses for leaks.
dave

Hi John.

Failing seals in either the slave or master cylinders usually give plenty of warning, was the clutch operating normally before the junction ?.

If it is the master cylinder you will probably find fluid dripping near the pedal.

Don
Don

thanks for ideas,

The clutch was pretty good before this.

The first i knew of it was when the pedal went to the floor and stayed there! It came back under the power of the spring.

I will have a look tomorrow in the daylight. Hopefully it will have stopped raining and the wind will have died down.
John Collins

G/day John What Don said, and you can also easely see a leaking slave cyl, but what can also happen is a weak primary cup in the master cyl. This will allow hyd pressure to leak back into the fluid resevoir and it stays full. When this problem first starts it may only happen now and then. It happens most if your foot is just resting on the pedal. It can happen to brakes too: G /Luck Denis
DENIS

OK

I've had a look under the car and the slave cylinder looks to be the culprit.

The rubber seal on the end of the cylinder had "ballooned up" and was full of fluid.

I'm off to order a new cylinder now.

Are these as hard/impossible to bleed as the ones on the midgets?

Any hints/tips?

Cheers
John
John Collins

When replacing the slave always replace the flex hose at the same time unless you know it is nearly new. Before starting pump out the old fluid through the slave nipple which will carry out a lot of old gunge with it. After reading all the tales of woe about 'bleeding clutches' I didn't event try, but instead filled the system from below using a gunsons EeziBleed on very low pressure connected to the slave nipple. As soon as I could see the fluid rising in the master I stopped the Gunsons then topped off from above as normal. Got the full travel - 1/2" to 5/8" of the slave piston immediately with no bleeding. Since then I have heard of connecting the RHS caliper nipple to the clutch slave nipple and using the brake pedal to reverse-fill if you haven't got an EeziBleed, keeping the brake master topped up of course.
Paul Hunt

John,

They are easy to bleed - no need for any equipment or fancy routines.

Drain out the old fluid as Paul suggests.

Change the slave by removing the old slave and hose from the car, swap the hose to the new cylinder, noting that it goes in the same hole as it came out of and refit to the car. If you just undo the slave from the hose and screw on the new one, leaving the hose attached to the car, it is possible that the hose will be twisted.

Refill master cyl with fluid and open the bleed valve until fluid drips out of the bleed valve. Top up master cylinder then open bleed valve and push the operating fork into the slave - air & fluid will squirt out, close valve and release fork, repeat till there is no more air, topping up the master every 3 strokes.

Chris at Octarine Services

This thread was discussed between 24/10/2004 and 27/10/2004

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