Clutch plate - strange marks

[Blink]

KV6.

There are some very strange marks on the driven plate I've just taken off - they're almost like woodworm burrows, they wander about all over the place and don't all follow the circular direction of rotation.

This is the flywheel side.



Same shot with top left quadrant enlarged.




This is the flywheel (made by LuK btw). There are no ridges or grooves - it's completely smooth all the way across but there's some odd patterning on it.




This is the gearbox side of the driven plate (not a very good pic). Similar woodworm tracks as the flywheel side.




Any thoughts?


The pressure plate was made by AP btw. Not sure about the friction plate but maybe safe to assume it's also AP. This is the factory clutch - it's never been changed before. Mileage 40k approx.

[roverbarmy]

Hard fibres of friction material separated by softer areas of the bonding material. Think of a tarred rope, hardened and sliced through the middle along its length. In the absence of asbestos, all sorts of friction materials and bondings have been tried.
Info:-


https://www.frictiontechnology.co.uk...velopment.html

[Blink]

Originally Posted by roverbarmy

Hard fibres of friction material separated by softer areas of the bonding material. Think of a tarred rope, hardened and sliced through the middle along its length. .....

Well that would explain why they're going off at all sorts of odd angles - but is it normal, or was this plate a particularly dodgy one?

It it's the latter it might also explain the why the clutch has been so impossible to use smoothly when pulling away.

[COLVERT]

It might be to your advantage to ask any of the site members who have great experience of clutches and their replacement to tell you if they have seen these types of patterns before and were they detrimental to the operation of the clutch.

The marks on the flywheel are simply imprints from the plate itself and not damage of the metal surface.

As in a previous post they could simply be indications of the composite materials that go into the construction of the driven plate itself.----

[ADO282]

They look completely normal to me, most of my clutch experiences are those of organic friction plates, but asbestos or not, that plate looks fine if a little worn.


I wouldn't be worrying too much, the flywheel on the Sprite looked much worse than that.

[roverbarmy]

Friction material never ceases to amaze me. When you think of the whole weight of a car, its load and passengers being held against a spinning engine (ie on a hill start) on a piece of friction material the same size as the outer section of a dinner plate, between two spinning steel plates! Go easy on those left feet folks and always use the handbrake on a hill when standing. I remember dismantling a truck clutch (double plate) and as the bell housing separated, I was covered from head to toe in burned friction material! Health and safety??? The driver got sacked as I remember!

[COLVERT]

Originally Posted by roverbarmy

Friction material never ceases to amaze me. When you think of the whole weight of a car, its load and passengers being held against a spinning engine (ie on a hill start) on a piece of friction material the same size as the outer section of a dinner plate, between two spinning steel plates! Go easy on those left feet folks and always use the handbrake on a hill when standing. I remember dismantling a truck clutch (double plate) and as the bell housing separated, I was covered from head to toe in burned friction material! Health and safety??? The driver got sacked as I remember!

All to do with gearing isn't it ???---Just serviced our grandfather clock. Massive main spring. You can feel the power behind it as you wind it. Great big heavy pendulum. Between these two items a tiny little release pin doing energy transmission from one to the other. This tiny pin will work for years and years with very little wear. A bit like a clutch plate on our cars if treated with care by a careful owner to reach mayby 200,000 miles or more.-----Yep, it's the gearing that does it.--

[Rich in Vancouver]

That pattern is typical and not an issue.

This is a new Borg & Beck clutch I installed in my MGF this spring, same friction material.

[Blink]

I just got a new friction plate and it has similar worms embedded in the material - just like Rich's pic of the Borg & Beck.

So it looks like there was nothing wrong with the original plate then - which is disappointing since I was hoping it was causing the judder I mentioned in post 91 here. Not to mention the other lesser judder I get every time I pull away from a standstill.

[ADO282]

Originally Posted by Blink

I just got a new friction plate and it has similar worms embedded in the material - just like Rich's pic of the Borg & Beck.

So it looks like there was nothing wrong with the original plate then - which is disappointing since I was hoping it was causing the judder I mentioned in post 91 here. Not to mention the other lesser judder I get every time I pull away from a standstill.

Simon, your original clutch plate is excessively worn, and the wear pattern suggests the clutch judder has been caused by the disc not disengaging properly, known as clutch drag



The splines in the centre of your friction disc are clearly rusted, the result of this is the disc cannot slide freely on the first motion shaft of the gearbox.


When refitting your gearbox, if you have purchased a good quality clutch kit, this will have included a sachet of high melting point grease which is designed to be lightly applied to the splines of the first motion shaft.


If your kit didn't include grease, then a smear of CV joint grease will suffice, but it is just a smear required and excess should be wiped from the shaft.