8.5" Clutch

[William2]

I have recently purchased a new old stock complete clutch assembly which has an 8.5" clutch plate and cover. I have been assured that this is perfectly ok to fit to an S4 4 speed Elan. Is this the case??

[LI-599]

Hi William?
I was having lots of shudder with the new 8" (Cortina) clutch in my S4, so after 2 attempts at fixing it-refacing everything, I installed an 8.5" clutch plate from an 80's Mitsubishi Sigma which has identical splines and it works a treat with no shudder and a better feel when engaging.I have read that 8.5" is standard.
Ian

[Panda]

Hi William,
All 4 speed Elans came with an 8" clutch. Only the 5 speeds were fitted with an 8.5" clutch. The bigger clutch probably comes with a slightly stronger pressure plate spring. I would happily fit the clutch you have as it should last longer than the original, although possibly slightly heavier to depress the pedal if it has a stronger spring.
Alan P

[rgh0]

As stated the 8 inch clutch plate was standard on the 4 speed but a 8.5 inch clutch plate fits inside the standard clutch pressure plate assembly that was used with the 8 inch clutch plate OK. You do need to get the surfaces on the flywheel and pressure plate reground whenever you fit a new clutch plate to ensure the clutch plate beds in properly and does not judder

cheers
Rohan

[William2]

Thanks for your comments. The new clutch cover part is also stamped with 8.5" and was advised that this is a standard size for all Elan clutches.

[types26/36]

As I recall the pressure plate for the 8" clutch had a centrally supported pad for the "flat" release bearing to press on while the 8.5" pressure plate has fingers with a slightly domed release bearing.
While you can use the 8.5" friction plate with the 8" pressure plate you should not mix up the combination of pressure plate/release bearing.

[William2]

This is a photo of the new clutch cover I am going to use. Is the release bearing centre pad correct? I'd hate to fit the wrong part!!

[rgh0]

Looks right to me

cheers
Rohan

[Craven]

Hi William,
You can confirm the diameter of the cover by drawing a PDC, pitch diameter circle, of 250.8mm on a piece paper and see this coincides with the fixing holes in the cover.
The original covers have the 3 cornered trust plate which gives the correct fitted height for the flat face bearing.
Ron.

[UAB807F]

Yes, that looks the right part for the Elan. The other version doesn't have that raised central hub in the middle, you have the release bearing working directly on the spring "fingers". The bearing you need for yours should have a flat surface to meet that hub, the one for the other design has a rounded shoulder.

This picture is from my Europa clutch (which has the 5sp version clutch) but it should illustrate the differences between the rounded shoulder/flat face bearings.

Brian

[ricarbo]

I read somewhere, many years ago, that it was a good idea to use a standard Elan cover plate, but the larger driven plate from the Ford Cortina GT. This is bigger than the Elan driven plate, but no bigger than the working area of the cover plate. The idea being it would last longer, I think.
So I bought those bits (good quality, Borg & Beck if I remember right) and fitted them, but it was a failure. The clutch slipped.
I only have a standard motor, so it wasn't due to excessive power. I don't know if one of the new parts was defective and since I hadn't stuck to standard bits I felt I couldn't return either of them as faulty. It occurs to me that a larger driven plate area will result in a lower pressure as the same force is on a larger area, but I would have thought that would be entirely offset by the larger area. Maybe it's not? I see Rohan suggests refacing the flywheel. Well, I didn't have that done as it appeared perfect. Maybe that had something to do with it slipping.
The cars been off the road a few years, but I hope to have it back together soon and I have bought new standard cover and driven plates from SJS, which I trust will cure the slipping!
But it was really disappointing, particularly as I had had the engine balanced and that included the pressure plate. So a new one won't be quite as good, but I won't be going to the trouble and expense of having it rebalanced. I will have to rely on the usual view that it will be ok as the balance of a new pressure plate is within acceptable tolerance.

But I wouldn't fit non standard parts again, unless I had very specific reassurances (with full details, including brand and part numbers) from somebody I trust and who has actually used them as to precisely which bits work together.

regards

Richard

[billwill]

Maybe the 'appeared perfect' flatness wasn't good enough and needed checking with engineers-blue and a flat plate.

Anyway that might mean that the clutch will bed in and work correctly after a while ??

[rgh0]

When fitting a new clutch plate my clutch man ( an ex Lotus Cortina racer himself) recommends grinding the flywheel and pressure late to get the correct flatness and surface finish and he will not warranty the plate from slip or judder unless you do. I have always followed his advise and never had a problem.

I use a 8.5 inch clutch plate in the standard Elan pressure plate housing. I use a solid bonded clutch plate which is more tolerant of racing start abuse. If you look at a standard clutch plate you will see it has a small degree of flexibility between the two friction surfaces as they are mounted of a flexible plate underneath, solid bonded plates don't have this. They bite a little quicker and are much stronger. I don't use racing clutches as they are too hard to drive for an amateur like me who also uses his car on the road a little, being very on or off and they are not needed in any twin-cam engine for my Elan I have built

The torque transmission ability of a 8.5 inch plate compared to an 8 inch plate in the same pressure plate assembly is the same and adequate for any twin-cam. The benefit is its greater surface area makes it more tolerant of overheating and abuse when it is working hard.

cheers
Rohan

[tonyabacus]

For clarity, the 8 1/2" centre plate can be used with the 8" pressure plate and likely to give a better result.

But is the 8 1/2" centre plate the one used in the 5 speed Elan and in this set up which thrust bearing should be used.

Also Rohan are you suggesting that even when using a brand new clutch assembly, this together with the flywheel should be ground, given that the clutch should be ground correctly straight out of the box

[rgh0]

I would always machine a flywheel face to ensure its surface preparation is totally correct unless i knew that had already been done by the supplier and I trusted them. A new pressure plate from a recognised manufacturer will generally have an OK surface finish but I would also closely inspect

cheers
Rohan