MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Clutch Wont Disengage - Slave OK Though

Hi all,

Driving home last week, I heard all these weird noises comming from the gearbox and I found that I couldnt change gears. Next morning I tried to start the car in gear with the clutch pedal pressed and it jumped, indicating to me that the clutch was still engaged. Bled the clutch line and the slave is working OK also but still cant change gears with the clutch pedal pressed and it jumped when I started it again. I also tried pumping the pedal to get some pressure but still no good.

Can anyone out there suggest what might be the problem ?

Many Thanks & a Happy New Year To you all

Chris '69 MGB



Chris Theodor

Chris,
Have someone push the clutch pedal in as you look under the car at the slave cylinder, if all is well you should see the rod move at least 1/2" to 3/4". If it does not then I would look at the master cylinder. If you do have enough movement then things are bad, either the throwout bearing or clutch plate is bad meaning an engine/gearbox removal.

HTH

Ron
Ron Smith

Thanks,

I thought the news was going to be bad. I did check the slave cylinder and it was OK moving about 3/4".

Whilst the engine is out, is there anything else I should be doing , I heard this was agood time to replace the rear welch plug.

Chris
Chris Theodor

Chris,
If it comes down to pulling the engine/gearbox I would at a minimum replace all of the clutch componets as well as the rear main seal. Also a good time to check all the motor and tranny mounts. Other things to check are the seal on the tranny input shaft, pilot bearing, flywheel (surfacing and ring gear) and the bearing/bushing on the clutch throwout lever.

Saftey Fast and Happy New Year

Ron
R

If the slave is moving back and fore with the pedal, and the resistance from the pedal is 'normal', then the release bearing and cover-plate would appear to be OK. This type of non-disengagement is usually caused by the friction plate being stuck to the flywheel which can be released by various means, but it usually only occurs if the car is left unused for wome time.
Paul Hunt

I had the same thing happen, it turned out the pressure (cover) plate center had come loose from the fingers. No surprise, it was a Q-H clutch kit with only about 6000 miles on it...
Ken Lessig

I'll need a reality check, but can't that symptom also come from some of the friction material coming loose from the rivets? A bent clutch fork could also allow the slave cylinder to move, but not disengage the clutch.

Sorry that neither of these suggestions would spare you from pulling the motor.


Matt K.
Matt Kulka

My 1965 MGB had that problem. I pulled the engine and the clutch fricion plate was worn out plus the pressure plate had several broken release fingers.

Don't forget to replace the bushing and bolt on the fork pivot arm as well as the rubber boot.

The other advice about seals, release bearing, flywheel are right on. My 1965 also had a chewed up starter ring gear. This can be heated and installed by a machine shop if yours is questionable.

Bob McCoy

My GT clutch made some strange noises and it would not release
there after. One of the coil springs in the clutch disk had come out
and jammed the works.

Good Luck,
Leland
Leland Bradley

It is only the pressure of the cover-plate springs that causes the slave to return, that's what makes the clutch self-adjusting. And isn't worn or broken friction material more likely to cause no clutch rather than a sticking clutch?
Paul Hunt

Obviously if the car jumps when you try to start it, the clutch is engaged - so it's not a worn driven plate or broken release fingers on the diaphragm spring.

If the clutch pedal feels normal and the slave is moving 3/4 inch then its not a hydraulic problem.

A bent fork arm will still operate the clutch as the system is self adjusting.

Is there an oil leak??

If the clutch plate is contaminated the driven plate may have stuck to the flywheel or pressure plate.

Alternatively it may be that the spigot bearing on the input shaft is seized - though I would suspect this would not make the car "jump".

Can you describe the type of noise heard, and was it with the clutch up or down??
Chris Betson

This thread was discussed between 30/12/2001 and 03/01/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.