Hints and Tips - MG Clutches

From: David Stansbie
Sent: 16 February 2000
To: British-cars-pre-war
Subject: J2 clutch

My J2 went on its inaugural journey to the MOT station on Saturday, some 12 miles or so. It passed the MOT with flying colours, I was amazed but may get used to cable brakes in due course. I reached the gate of the MOT station when the clutch died. It is jammed such that it won't release. I took the clutch stop bolt off and tried abusing it by pushing the pedal as far as I could and stamping on it a few times. No joy. Looking through the inspection cover I can see the cover plate pressed forwards onto the driven plate and the clutch fingers are not pressed against it. I expect that I will have to strip it down but I wonder if this is a common fault and there might be a simple remedy. Any advice would be gratefully received.

----------------------
David Stansbie


From: Ian Grace
Sent: 16 February 2000
To: David Stansbie; British-cars-pre-war
Subject: Re: J2 clutch

David,

Hmmm. The clutch is released by three hardened steel pins that bear on matching hardened thrust 'buttons' let into the outer circumference of the alloy pressure plate, just beyond the edge of the driven plate. These pins are held in place by virtue of their running in holes in the cast flywheel cover plate. If the clutch won't release (and it was for the previous 12 miles) then it almost sounds like the pins have escaped, which they could only do if the thrust bearing assembly and levers allowed them to, which doesn't sound very likely - but is easy to check. It might also be worth checking that the pins are not fouling the outer edge of the driven plate, although this could only happen if your driven plate is over-size.

The usual problem is slightly different - the splines on the gearbox input shaft wear on the driven side, and the driven plate then engages with the work section, preventing it from sliding on the splines. But I doubt if this would get so bad as to hold the driven plate hard against the lining on the cover plate.

Among other derangements I have seen, are the break-up of the steel thrust bearing cover plate, caused by the hardened inner tips of the clutch fingers grinding their way through it over time, and turning the front face into a quite separate washer which can gum up the works quite nicely.

What new parts have you fitted during the rebuild?

Hope that is of some use, enjoy the car,

Ian Grace


From: Dave Dwyer
Sent: 20 February 2000
To: mg-mmm
cc: british-cars-pre-war
Subject: MG PA clutch

Gentlemen (and Ladies if any)

We're in the midst of extensive reconditioning of our PA engine. When it's finally reassembled we hope for all 35 bhp for the first time in quite a few years (maybe more 'cos reboring increases both the swept volume and the CR).

However the clutch plate is 30 years old and the pressure plate assembly over 60. With a major engine rebuild I'd normally replace these automatically, but how?

The guys in Melbourne have used a Datsun clutch in the PA, but it's said to be heavy to operate. Someone here in Sydney has installed a Hillman Hunter assembly, and I ##know## that's very heavy. OK for the track but a problem on the road.

I will value any suggestions: I'm sure that the collective mind has a solution.

Regards

Dave Dwyer
MG J2/PA engine


From: Jack Hardy
Sent: 20 February 2000 18:00
To: jasper
cc: mg-mmm; british-cars-pre-war
Subject: Re: MG PA clutch

Dave,
I've had good results from Sports & Vintage in England, Tel: 01939 210458, Fax:01939 210644. They are knowledgeable, and helpful and will accept a credit card so it is easy to do business by phone. They have a catalog with descriptions and a few photos. They seem to have a good supply of parts on hand and can get a lot of items if they are not on hand.

Good Luck
Jack Hardy
"34 MG PA



From: Patti & John Morris
Sent: 21 February 2000
To: Dwyer; mg-mmm
cc: british-cars-pre-war
Subject: Re: MG PA clutch

Hi Dave,

I have a J2 and F type that I've rebuilt the clutches on. The P type clutch is similar. Mike Dowely at Sports and Vintage in England has all the parts. I needed the two fiction linings with rivets, new springs (6) for the pressure plate, new clutch fingers (3) with adjusting screws and a new release bearing. I didn't replace the disk that has the splines as mine were both in good shape.

This clutch design is a little different than a modern unit but the rebuild is pretty straight forward. The rivets holding the fiction lining are drilled and removed. The new linings are installed by riveting...like relining old style brake shoes. I had to make up punches to set the rivets as my brake relining set wouldn't reach. On the disk, check for wear on the disk faces and wear on the spline. Check also for wear on the gearbox input shaft. If the shaft is "stepped" it makes it hard for the spines to slide. I replaced the springs because they were old and not all quite the same length. The tips of the 3 fingers (4 on the P) operate against the release bearing and were worn enough I thought might affect operation. The release bearing is a press fit on the bronze carrier. It came apart and goes back together easy. Check the carrier for wear especially where the pedal shaft fork pushes on it. There are also small pins that the fingers push against. The holes for these pins were very worn on both of my cars and I made up new bushings and pins. Make sure you install the disk with the splined center hub turned the correct direction...check your manual. Check for wear on the bushings where the pedal shaft passes through the clutch (bell) housing.

I've had no problems with the J2 clutch but the F clutch is yet to be tried. Rebuilding should be easier than trying to find modern parts that will work.

Best Regards,
John Morris
Wisconsin


From: Ian Grace
Sent: 21 February 2000
To: Dwyer; mg-mmm
cc: british-cars-pre-war
Subject: Re: MG PA clutch

Dave,

I'd echo others that Mike at S&V is your man.

I can add that Mike also has ali cover plates (certainly for the J2 - probably for the rest) which reduce the rotating weight considerably.

They also carry a range of clutch springs, so if you need a strong clutch (for trials, etc.) then you can fit springs with a stiffer spring rate.

Good luck,

Ian Grace


Home | Hints & Tips | Suppliers | Engineering Data | Links | Events | For Sale | Gallery | Books | Videos | About Us