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MG Midget and Sprite Technical - Clutch pressure plate

Car - 948cc Mk2 Sprite, mildly tuned, about 65 bhp at flywheel.

When I first rebuilt the engine about 25 years ago (standard spec) I fitted a 9 spring clutch pressure plate - no idea why! Since then the engine has been tuned to about 65bhp at flywheel.
There is some wear on the pressure plate where the release bearing touches so thought would replace it.

2 questions:
- Where can I get a 9 spring pressure plate - can’t find one.
- Do I need a 9 spring or will a standard 6 spring be ok?

Thanks

Les
Les Robinson

IIRC they were fitted to the smaller engined Triumph Spitfire so you might want to check the usual suppliers.
David Billington

David
Just checked and yes same clutch is fitted to the Mk1 Spitfire, I didn’t know that.
Still can’t find a 9 spring version though, if I actually need one!
Just thought, maybe I could clean up the face where the release bearing touches, probably only about 10-15 thou to come off.
Les
Les Robinson

My original 948 engine is about the same spec as yours. For several years I struggled to get a 9 spring clutch to work. Yes the Spitfire one fits, but I always found the pedal pressure was much too high. Eventually I gave up and got the flywheel drilled to accept the 1275 diaphragm clutch. The best thing I ever did. With a roller release bearing it is totally trouble free. At about the same time I fitted disc brakes so sleeved down the master cylinder, which suited the 1275 slave as well as the disc brakes.
Les Rose

I’ve had no issues at all with the 9 spring pressure plate.
Have had a roller release bearing for quite a number of years now. I’m guessing that the slight wear I’ve noticed on the pressure plate is from when I had a carbon release bearing. Maybe it doesn’t matter as it’s probably been there for years as the roller release bearing shouldn’t cause any wear.
I’ll probably keep the 9 spring plate that I have, the slight wear I’ve noticed is causing me to over think things and worry about nothing - hopefully!
Les
Les Robinson

Les
My 948 (bored 1046) is / was 62BHP on a stock 6 spring.
Your plate & cover can be reconditioned by specialists.
Alan Anstead

Les R. The damage you note to your pressure plate is, in fact, caused by your use of a roller bearing. The bearing does not rotate with the pressure plate (or it will wear out very quickly), but must be retracted slightly so that it is not constantly rotating. When forced into contact with the pressure plate, it has to start at zero rpm and, very quickly, come up to full engine rpm. Hence, a minor bit of skidding results on wear on the contact surface of the pressure plate. The factory carbon throwout bearing is self lubricating (e.g. graphite is used to lubricate lock cylinders in cold weather) and normally shows no damage to the pressure plate unless the carbon portion is completely worn out and the cast iron carrier is making contact.

Your estimated depth of damage, .010"-.015" is rather deep to try to take out on your own. Remember, it must be perfectly flat and concentric if it is not to cause problems with the throwout bearing due to inconsistant contact.

Due to labor costs here, it is often far less expensive to purchase a new item than to have an old item disassembled, machined, cleaned, and reassembled.

Have you asked Peter Burgess about what he recommends?

Les B
Les Bengtson

Not all roller bearings are the same. Americans tend to berate them because of comments by John Twist of University Motors (?).
Whereas they have been in use in UK for many years now.
Some roller bearings have the ability to self centre and / or run off centre (but are not available in USA). Not all roller bearings are the same.

I am still producing my popular release bearing (top pic) for 1275’s when using a stock clutch whilst Robin Human caters for 948 & 1098. (Lower pic).





Alan Anstead

Alan's roller bearings are a very good and well tried solution. fitting one is a no-brainer when the clutch is accessible. I have one on my 1098 Sprite.

On my 1275 I fitted a ford concentric slave and turned up a block of aluminium for the mount/ input shaft seal. A good deal more work but an exercise in DIY before Alan was making his.

But, Les B, this concentric version is a constant contact bearing - It has a light pressure spring that keeps the bearing in contact with the clutch all the time, spinning with engine revs. It could be considered as the bad habit of lightly riding the clutch! but it is designed to avoid the rapid 0 - 6,000 rpm and back to 0 every time you change gear, that you get with a standard "disconnected ' release bearing. With the clutch apart recently after 60,000 miles there was very little indication of wear on the clutch cover and none apparent on the bearing face at all.
GuyW

As Guy says, fitting a roller release bearing is a no brainer.
I fitted one, probably 10 years ago. I was given a Colin Dodds thrust plate and then fitted my own bearing into a standard housing after removing the carbon. The bearing was quite a tight press fit into the housing which was always a concern to me.
The slight wear I have noticed on the clutch plate is probably only a thou or so if that and not the 10 to 15 thou I first guessed at!! I think this is due the the clutch arm moving through an arc thus causing the thrust plate to run slightly off centre from the clutch.
I have now fitted a new Colin Dodds bearing, didn’t clean up the clutch face as the bearing thrust plate is exactly the same so should be in full contact.
Les Robinson

Before I knew about Alan's version, I went through two standard release bearings - there was a time when the carbon release bearings sold by the usual suspects, were of appalling quality, so I fitted a Peter May roller version. That was about 2009/10 and it's still working fine, it is as previously stated, a no brainer.
Jeremy MkIII

This thread was discussed between 06/04/2025 and 14/04/2025

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