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MG MGB Technical - clutch release bearing

After bringing my 68 BGT out of winter storage and alas, prepping her for sale :(
I've discovered a whirring noise when the clutch pedal is depressed. It occurs at the floor or at the bottom 2 inches of travel. The car runs and shifts fine otherwise.

The engine and new clutch and release bearing have less than 4,000 miles on them since rebuild.
Last season i did remember having to add fluid to clutch masyer cylinder and had to do that again this spring. After examining the slave cylinder, i've noticed it leaking fluid from the boot.

One would think the bearing is the culprit, or does the leaking slave cylinder come into play here? The noise does not go away when the cylinder is topped off.

Before i pull engine, does anyone have any experience or input on this problem.

thanx for any response

Dennis Silance

Do you happen to know if the throwout bearing, used in the clutch replacement, was the standard carbon unit or a roller bearing? RAY
rjm RAY

Hello Dennis,

There are many stories about carbon release bearing, see archives. There was a batch of poor quality...

See also:

and also that DIY roller bearing swap:


Jean G.
Jean Guy Catford


I forgot to read your post completely; a leaking cylinder could cause an inefficient action of clutch and may cause noise and a car having tendency to move and has a hard 1 gear engaging, which is not a your case. Try to solve that leak to see if it will solve your problem.


Jean G.
Jean Guy Catford was the standard carbon type

Jean...i do plan on installing a rebuild kit on the slave cylinder first...and hoping...with fingers crossed
Dennis Silance

I fear that you may have gotten one of the flawed carbon throwout bearings, when your clutch was replaced. You may have to pull the engine to find out. The place, where you purchased the clutch kit, will probably replace the throwout bearing free of charge, but that won't help with the labor of removing and replacing the engine. RAY
rjm RAY

The boot on the clutch fork can be removed and should give you a chance to visually inspect the bearing. Might take a mirror and flashlight to see clearly. You can move the fork manually. I recall on some MGB or MGA that I owned along the way finding that one of the clips that holds the two mounting points for the release bearing had managed to rotate out of position. It forced the release bearing to engage the pressure plate at an angle instead of freely rotating into a straight on position. The clutch would engage nevertheless, but the whirring sound you spoke of was the symptom that forced me to take it apart and find it.
Rick Penland

Follow up: renewed slave cylinder and re-installed and noise has disappereared. must haave been the culprit, as Jean G. suspected.
Thanx for the input guys....I can return the new throw out bearing i bought just in case.
Dennis Silance

I'm glad the noise has gone without getting the engine out, but noise when the clutch pedal is at or near the floor is much more likely to be problems with the release arm and throw-out bearing. Lack of movement of the push-rod, i.e from air in the hydraulics, wouldn't cause that. It may be that removing and reconnecting the slave cylinder to the release arm has corrected any alignment issues of it to the release bearing.
PaulH Solihull

This thread was discussed between 30/04/2011 and 15/05/2011

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