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MG MGB Technical - clutch release bearing

After ca 2000 miles my carbon-type release bearing is completely gone.
I took out the engine and discovered that the clips (to secure the bearing)were turned 90° (strange!!)

Possibly, the bearing face has always been in contact with the clutch cover.

Any idea how this is possible?

Thanks
André

Installer error, perhaps? As I recall, they "latch" rather firmly when rotated into the correct position....
Rob Edwards

Driver's left foot always covering clutch pedal. Never touches it !!

Is this a possibility?
Iain MacKintosh

It could also be:

The hydraulic system always has a bit of residule
pressure left in the system to cause the bearing to
make light contact with the clutch plate.

This is normal.

However, if something (debris, or ?) is caught in the hydraulic system and is not allowing the bearing to release as it was designed...then this contact pressure may be greater than it should be
- and this may be your problem.

Check the travel of the throwout arm.
Daniel Wong

Iain, David,
Both could certainly cause premature throuw-out bearing wear (as could a missing pedal return spring), and should certainly be checked. I don't see how either would, however, cause the bearing retaining clips to be out of position. My $0.02...
Rob Edwards

Ian,

Driver leftfoot definitly not! It would be a shame after 20 years MG driving and many competition miles

Rob,

Installer error? you have a point that it is strange that the clips are turned. On the other hand, the remains of the bearing carrier must have been red hot...could that (temperature and forces) cause the clips to rotate?

Daniel,

at this moment, i am going the same route as you
I just removed the slave cylinder and checked the hose.The rubber looks Ok but it is difficult to forsee what is going on when the thing comes under pressure
I will also check, clean and replace the internal parts of the master cylinder
How can i check the travel of the throwout arm?

What about adding a spring on the pushrod to minimize the residual line pressure?

thanks

André
andré

Perhaps, if the bearing assembly got really hot, the clips could have lost enough temper to become loose. But if it was just the carbon rubbing clutch cover, I doubt it would produce enough heat to do that. Does the bearing carrier show signs of extreme heating? And do the clips fit tightly now? If there's no indication of heat and the clips are tight, then I'd lean towards the hypothesis that the clips were a cause of the failure rather than a result. And of course, the opposite applies.

I don't think a spring on the pushrod is the answer. It would just be treating the symptom, not the cause...

Keep us posted -- I'm very curious to find out what caused this!
Rob Edwards

The clips are a red herring - the bearing would not come out even if they were totally absent and the bearing is held lightly against the clutch by the spring inside the slave cylinder anyway.

The problem is in the hose or the slave cylinder.
Chris at Octarine Services

Lately, I tend to completely rebuild my B's engine every 4-5000 miles and during the last operation I noticed that my release bearing was worn at an angle. It was the original thickness on one side and worn almost to the carrier on the other. The pivot bolt was tight and straight, the fork was straight and the pressure plate was fine. The clips were in place and it had been installed just a few thousand miles earlier. I've never seen this before. I installed a new one and it sits flat against the pressure plate. Any ideas?
David

Hi Chris,


I can't see something wrong in the slave cylinder, so i 'm planning to rebuild it with a new rubber cup.

Would it be the best choice to replace the hose with a PTFE lined hose?
It could be that the 5.1 fluid i use is to agressive for the rubber...

What do you think of installing an extra return spring on the slave cylinder?

Thanks,

André
andre

Check this out:

http://www.mgbmga.com/tech/mgb2.htm

Be sure that all of your hydraulics are in order
before trying this mod.

I suggest you try a steel braided teflon hose
on the slave cylinder if you install this mod.
Daniel Wong

Hose should be OK Andre no need for a spring, but hydraulic system could be a problem. I would tend to suspect the master cylinder. It would be worth disconnecting the pipe to flexible joint at the chassis leg and then ensure that you can push the fork right back, i.e. the piston fully into the cylinder against its spring. If this is OK then it is the master - if not disconnect the flex at the slave and try again.
Iain MacKintosh

This thread was discussed between 28/06/2004 and 29/06/2004

MG MGB Technical index

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