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MG MGB Technical - Can a clutch need adjustment?

Son Brian posted a thread on his clutch and thanks to help we knew it must come out. It turned out to be a worn clutch disc, a B + B put in five months ago. My thoughts - son is riding the clutch, needs more shifing lessons, or we should have adjusted the clutch after the last install, possible? I thought to leave the flywheel and pressure plate alone; they are smooth. Votes?
brian beedie

Brian;

If clutch is being ridden too much, check flywheel for bluing or very fine radial cracks from overheating. You should have it turned at a machine shop. usually costs about $25.00. Since it is a fair bit of work to get at the clutch, I would replace all the components. The kit is usually $95-105.
There is no adjustment to the linkage rods on a B that I am aware of.
If he pays the bill, he'll think about how he is using that clutch a little more next time.

Pete Haburt
Pete Haburt

Riding the clutch, in fact just keeping the clutch down in an MG will cause accelerated wear on the throw out bearing but should not cause the clutch disk to wear. Have you checked for a blocked return opening in the master cylinder. Something like this would cause the clutch to remain disengaged longer than usual (although I have never heard of this situation). Normally, with the MGBs, the problem is that the clutch dosen't want to disengage untill the pedal is on the floor due to wear in the linkage.
Good luck - Dave
David DuBois

A couple of things you may want to check, when you replaced the clutch did you inspect the linkage? The pivot pins on the throw rod from the slave cylinder will wear, as well as the hole on the rod. Same situation on the rod and pin from the master cylinder. The Clutch pedal pivot will wear as well. All of this wear will cause a lot of loose feelings/weak clutch action. If one rides the pedal, then many other problems most likly a worn release bearing.

HTH
Ron
Ron Smith

The common wisdom regarding clutch use in an MGB seems to be: don't depress the clutch pedal unless you are changing gears.

In practice that means you take your foot completely off the pedal while driving, and when stopped at a traffic light, put the transmission in neutral and release the pedal. Most of us, I think, start the car in neutral, as well. I know that I do.

When you replaced the clutch 5 months ago, did you have the flywheel resurfaced? Perhaps it was worn and in turn caused excessive wear on the new clutch.

Riding the clutch is definitely a BAD thing, but I would think that it would destroy the release bearing before it wore out the clutch disk. Unless you were riding it hard enough to cause the clutch to slip. This would show up by the engine speed increasing while the car speed remains the same.
Paul Noble

Hiya,

Seems to be like it was a duff driven plate or there is something wrong with the flywheel or pressure plate. There's no way anyone could totally toast a clutch in 5 months - my last clutch took 2 years of very severe abuse from yours truly (including *trying* to lunch it so that it would free... problem turned out to be the spigot bush...), driving the car lots every day, and came out looking very healthy with plenty of life left in it.

Have the flywheel checked and buy the complete clutch kit. It doesn't cost too much and it takes a long time to take the engine out again. If the new clutch slips then start worrying about the hydraulics but they usually don't hold the clutch off.

Hope this helps,
--
Oliver Stephenson
Oliver Stephenson

I agree that you should purchase a complete new clutch kit. I would also replace the spigot bush/pilot bushing while I was at it. As I see it, there are two possible causes of the problem--mechanical or operator. The spigot bush should have been replaced, the flywheel should have been turned, the master and slave cylinders should have been rebuilt and the flex line replaced. The pushrods should have been inspected and replaced if they show significant ovaling. It is possible, if the system is not working correctly, that the clutch was not releasing properly. This would show up as wear on the driven plate/clutch disc and on the throw out bearing. By comparing the old pieces with the new, you can get an idea of whether this was a problem. As Oliver notes, the standard clutch is very robust and holds up well even with agressive driving. But, this is with an experienced driver, which I suspect your son may not be. Once again, the wear on the throwout bearing may provide a clue. If it is worn, it may be due to holding the clutch in at traffic lights, stop signs and starting the car with the clutch pedal depressed. But, this type of behavior normally affects the throwout bearing more than the clutch plate. Excessive clutch plate wear is normally caused by reving up the engine and popping the clutch, speed shifting (racing change) or downshifting without double clutching. All of these put excessive wear on the driven plate/clutch plate by causing it to bring the engine speed up to/down to the wheel speed and slipping while it is doing so. So start with the mechanical and get the system working correctly, then look to operator training, if necessary. Les
Les Bengtson

Another thing that should be kept in mind: New clutches need a gentle "break in" period for at least
a couple of weeks, or better still - a month.

The friction material on a new clutch disk includes fresh organic and inorganic compounds which
contain embedded oils and resins. Any excess heat generated during the "break-in" period will cause
these oils and resins to melt and sweat to the surface and set up a smooth glaze on the flywheel and
pressure plate. The result: chattering during engagements, slipping, shuddering, and all sorts of odd noises and vibrations during shifting, as well as premature failure of the friction material itself.

Remember, during the "break-in" period...

...no rip-roaring, tire-burning launches.

...no holding the car stationary on a hill or incline by riding on the clutch.

...no engine-howling downshifts when leaning into turns or braking to a stop.

...make careful launches and smooth shifts. Not too fast...not too slow.

If there's any excess cheating on these points, you'll soon know it, because you'll be having to haul
out all the works, yet again, to correct it.
Daniel Wong

The clutch is self adjusting and that includes all wear in the linkages between slave piston and friction plate - otherwise it wouldn't be able to compensate for wear in the friction plate. However wear in the linkages between foot and master cylinder will cause the clutch to engage closer to the floor than it should.
Paul Hunt

This thread was discussed between 26/03/2002 and 29/03/2002

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