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MG MGA - For you Sierra 5-speed people..

Have any of you experienced a scraping, grinding, or squealing kind of noise from your clutch when you depress the pedal to shift? It happens to me and it doesn't occur until the foot has depressed the pedal to the point where it's approaching the floorboard towards the end of it's "stroke". The clutch disengages enough to easily shift through the gears before my foot depresses the clutch far enough to hear the noise. The clutch push-rod adjustment isn't the problem.
Ring a bell with any of you?
Thanks..
Rick deOlazarra

Whether it it the thrust bearing or pressure plate doesn't matter much - let us know what the problem is when you pull the engine out!
Mike
Mike Ellsmore

I had this years ago with a standard A clutch. It was throwing over centre and the release fork was rubbing on the clutch levers. We couldn't figure out why, and replacing the clutch cover solved the problem.

You are going to have to take the engine out.
Dominic Clancy

Rick

I suffered something similar about 8 years ago, accompanied by some clutch juddering on engagement. It turned out that I had not tightened up the clutch operating arm pivot bolt sufficiently. This accelerated bush wear, resulting in lateral movement of the arm. This in turn caused the release bearing to run off centre. See photo.


Steve Gyles

It sounds rather similar to when I ran out of carbon on the clutch release bearing. The clutch still worked and was being operated by the metal backing pressing against the clutch pressure plate. There was a nice set of grooves on the pressure plate where the "bearing" had been making contact.

I have no idea why that particular bearing wore out as it has never happened before or since. It was about 10-15 years ago and the bearing was of unknown source and vintage.
Malcolm Asquith

Just found a picture of the arrangement inside the Type 9 bellhousing showing the problem I experienced above.

Steve


Steve Gyles

Hi Rick,

Certainly does ring a bell. Happened to me just after I had installed my T9. I took the whole thing apart again to locate the problem.

It will be the spigot bearing slipping in the flywheel. When you installed the T9 conversion you fitted an adaptor to bring the spigot bearing closer to the gearbox. Assuming you used the Hi-gear kit, it was a hammer home interference fit with a knurled area about halfway down to aid grip. It was supposed to be fitted with a good coating of Loctite to stop it slipping.
My money is on the Loctite being missed or not enough applied to it, or possibly a greasy spigot hole (using grease and a drift is the usual way of extracting the old bush).

IMO It's not really worth fixing unless you are very worried by the noise. I found it only seems to happen on very wet days, if you are working the gearbox fairly hard.
My best suggestion is to get a spare insert from Peter Gamble (around £20) and keep it in stock.

Hope this is helpful.

Paddy
Paddy Reardon

Thank you for your responses!
After the 5-speed conversion, I remember driving it without the described problem for quite awhile. Then I started hearing the sound.
I "got around it" for a brief period by adjusting the master cylinder clutch push-rod in order to extend the amount of push on the clutch pedal before the sound would happen, but knew I couldn't live with it without addressing the cause.
Since I didn't have the work space or facilities to pull the engine, I opted to pay someone in the know to tackle it.
MG mechanics are getting pretty rare and I ended up taking it to a place 75 miles away where I explained the problem.
A relatively short time later they called and said the car was ready. How could they pull the engine, solve the problem and put it all back together so quickly? Turns out they didn't. What they had done was the same thing I'd done (adjust the m/c push-rod) while additionally shortening the clutch slave cylinder push-rod a bit.
Although the problem was not as apparent, it was still there, and I wrote back to them.
Now, the guy is a very likeable fellow who took a rusted pile of junk in pieces and restored it into a multiple award winning MGA, and when he got my letter of complaint, he responded in the following manner, (keeping in mind that I'd also asked that they check out the condition of the gearbox):
..............................................
"My approach with customers is not to do major work unless it really needs to be done. Since the transmission was solid, as compared with other Sierra boxes, I began to feel that pulling the engine might not be needed if we could eliminate the squeal. (I believe I mentioned that we'd seen/done other conversions and this was a problem we'd run into...and could solve.) We did the repair, and when I drove it, it did not squeal. It is not uncommon, for this problem, to need one of two things after the initial adjustment. The first is to refine the adjustment, after some miles are put on the car, IF that does not solve it, the other is do, like the factory does for the gas pedal, put a physical pedal stop in the car on the floor board. This prevents the clutch fork from over extending and squealing the pressure plate. My approach, for free of course, is to do one, or both of these things when you bring it back. PS: pulling the engine does not and cannot fix this issue."
............................................

I don't know; I just had to run it by you people to find some other, or more, insight. Why doesn't every Sierra user have this problem? Why did I not have the problem, and then did? How does pulling the engine not get to the problem? Are there different versions of the Sierra conversion hardware that invites this problem while others don't?
Anyway, there you have it; and thanks for all your feedback.
Rick deOlazarra

Thanks, Paddy; I wrote my last post before I saw yours...
Rick deOlazarra

Not sure if this is going to help - but -

I fitted the T9 Ford gearbox in my '57 Magnette and after a couple of thousand miles the clutch pedal developed a pulsation (no noise though).

Long story short, I removed the engine, split the gearbox off and found a misalignment between the carbon thrust and the (MGB) clutch pressure plate (See pictures)

The problem was caused either by a misalignment of the clutch arm pivot drilling in the Hi-Gear bracket or a distorted clutch withdrawal arm. The second picture shows that bracket and arm sitting on plate glass, with one side of the fork resting on the glass while the other side is elevated.

Both bracket and arm were replaced and problem solved. However I DO use a stop under the clutch pedal to avoid over-travelling the diaphragm spring using the Magnette hydraulics.

Andy


Andrew Dear

Second image


Andrew Dear

Rick,
Is your T9 from a British Sierra, or from a NA Mercur? The latter does not need the spigot bush extender supplied by Peter Gamble in his kit, and in fact the gearbox/engine cannot be assembled if you put the bush extender in because the gearbox spigot bottoms on the bush before the bell housing gets to the engine plate.
All you need is a new bush to match the OD of the gearbox spigot. However, this does not explain your noise - my guess is the thrust bearing is worn or out of line. Did you fit a new thrust bearing.
Or the spigot bush might be dry. Did you soak it in oil for 12 hours before fitting it. It is sintered as has to be well lubricated.
Peter.
P. Tilbury

How many miles did you go before all the issues cropped up? Ive got about 10,000 trouble free miles on mine (knock on wood) I hope my good luck continues!
Steven Devine

This thread was discussed between 18/02/2014 and 20/02/2014

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