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 MGA - Clutch cover assembly height variation

I have a 1957 MGA with an 1800 cc, 3-main engine. I have just installed a Ford Sierra 5-speed transmission and driveshaft from Hi Gear Engineering. I have all MGA clutch components and flywheel.
My clutch seems to be working well enough. The pedal is hard, and the slave cylinder piston moves by about ½” when the clutch pedal is depressed. Here is what happens next.

Engine off, clutch pedal held down, trans in 1st gear. Pull starter, car lurches forward, showing that the clutch is not disengaging.

I pulled the engine and found out why there is no clutch disengagement:
(Note that the clutch disk was mounted correctly. It was not backwards.)

See the two attached photos. The first shows new wear on the inside faces of the clutch fork (red arrows). This was not there when I put it all together the first time.

The second photo shows where the fork wear came from: the ends of the springs in the clutch pressure plate are scuffed and polished (black arrows) all the way around.

It seems that the carbon release bearing was coming forward as it should, but it was being stopped by the ends of the pressure plate springs. So it was prevented from making good contact with the pressure plate face, and the clutch wouldn't disengage.

What got me thinking about this was the MGA Guru's tech page CT-100A, a recent post regarding variations in MGA clutch pressure plates. Measuring mine as the photos show, I get 35 mm, which the tech page shows as "not optimal." The wear on the inside faces of my clutch fork is like that shown in the last, lower right photo of the tech page.

I think my problem would be corrected if my pressure plate measurement was around 42 mm (top right tech page photo). I’m looking for such a pressure plate assembly. I’d rather do this than change to an MGB clutch system.
Any comments would be most appreciated!
Mike Whalen






M.E. Whalen

There vare different heights of the fulcrum tower mounted on the Sierra box. You might add a 1 cm thick plate under it but You should check the concentricity of the carbon ring when pushing against the metal centre.
Did You mention You had an MGA clutch system?
Dirk Van Ussel

Dirk:

That is a good idea! I have an MGA clutch system.
M.E. Whalen

The obvious question from what Dirk says is did High Gear supply the correct fulcrum tower for the A clutch? Attached is the tower that came with my kit having told them I was using the MGB clutch assembly on my 1800 engine. Ignore my arrows. That was for another story.

The problem I had in the early days back in 2000 was that I didn't tightened the fulcrum bolt enough and got very rapid wear in the bush causing off-centre wear on the thrust bearing (second Photo). It showed as fierce juddering on clutch release. Since then it has all worked perfectly.

Steve






Steve Gyles

Steve: Thanks for your comments! They're very helpful. Do you by chance know the dimensions of the MGB fulcrum tower?

Yours probably stands a bit higher than mine, since I understand that the B clutch pressure plate is not as tall as the A.

Mike
M.E. Whalen

You should get there with a 10 mm alu plate,but I think You will also need an MGB 3-Brg Clutch fork to get the carbon ring centered.
Dirk Van Ussel

Dirk:

Thanks so much for your helpful comments! I'll try a 10 mm alum. plate today.

Mike Whalen
M.E. Whalen

This thread was discussed between 09/08/2022 and 12/08/2022

MG MGA index

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