Clutch judder

DavidThompson · Posted: Sun Sep 15, 2019 4:20 pm Post subject: Clutch judder

As a novice WO driver, should I be worried about clutch judder, experienced mainly in low speed manoeuvring and especially in reverse?
The car is a 3/4.5 with a cone clutch. I have not had any uninduced slip, and seems fine in all other respects, although I have had it jam on one occasion. ( a bit nerve wracking approaching a roundabout and finding the clutch very reluctant to disengage!)
Is this all normal or do I need to take some action?

John Murch · Posted: Mon Sep 16, 2019 10:08 am Post subject:

David, I’m no engineer so I hope you will get better responses from others!
Firstly I would not be unduly concerned, I think this judder can be improved by adjusting the fingers and chamfer of the lining.
Jamming tends to occur if the car is unused for a while, some people keep the clutch disengaged (with a pole suitably wedged between pedal and seat).

Iain Warner · Posted: Mon Sep 16, 2019 10:25 am Post subject:

Like John I am no engineer although I do most of the work on my 3 litre myself. I would also think the fingers on the clutch ring would be the first thing to look at, but it is quite a bit of work to disassemble to get the ring out.
Also can you confirm that it is the clutch that sometimes jams (ie you cannot push the pedal down) rather than the gears jamming so you cannot disengage - in which case it may be that the clutch stop needs adjusting.
Iain

DavidThompson · Posted: Mon Sep 16, 2019 5:36 pm Post subject:

John and Iain, thanks for your replies.
I'm certain it was the clutch. The gearbox seems quite happy, even with all the abuse I am subjecting it to.
The clutch disengaged after stamping on it with some force, and has been fine since then, although it does emit squeaking
noises when made to work hard.
It is probably me rather than the car that is at fault. I will continue as it is and see what happens. I was just concerned that the clutch might benefit from early attention.

Iain Warner · Posted: Mon Sep 16, 2019 6:41 pm Post subject:

David, As you have confirmed that it is the clutch that sticking I would say that this again points to the fingers on the outer ring. The edges need to have a smooth chamfer to avoid catching on the lining material and causing the difficulty you have experienced disengaging.
That is the square end of each finger and also along the length where it runs proud of the body of the ring. I think you have many hours of fun ahead with a small file, unless someone else has a better suggestion! Section 2.6.1 of the 'Technical Facts' gives a good description.

DavidThompson · Posted: Tue Sep 17, 2019 11:34 am Post subject:

Iain, I wonder if I have a different edition of "Technical Facts"?
The only reference I can find is on page 22/25b

Iain Warner · Posted: Tue Sep 17, 2019 2:24 pm Post subject:

David
I think you must be looking at the 1984 edition. I was referring to the current A4 size edition which is greatly expanded and includes quite a number of diagrams. However the wording you have half way down page 22A is broadly the same in the description of the aforementioned fingers.

Robert Craven · Posted: Thu Sep 26, 2019 1:31 pm Post subject:

When I first had my 3 Litre the cone clutch used to jam occasionally (which could be very disconcerting). As an emergency solution I used to have to stop and carefully hit the cone with the hammer for the wheel locking rings. (Someone walking past my car at the roadside suggested this. I've no idea who he was, but he must have known about cone clutches.)
Eventually the problem went away (except for one occasion when the clutch slipped badly because I had to tow someone) after the clutch lining was renewed because it had worn, at which time I may have adjusted the fingers, but I'm not sure exactly what cured the jamming.

Paul Spencer · Posted: Fri Oct 04, 2019 9:38 am Post subject:

David,

This sounds a little like something I had. I was forced to start on a 1 in 4 hill in Wales by a car coming down the single-track road and with cars behind me. The handbrake wouldn't hold on the hill. After unsuccessfully trying to start using foot brake and hand-throttle, I ended up starting while rolling slightly backwards. Big mistake! The cone clutch expressed it's opinion of my driving with an unpleasant smell. I had already had some juddering in reverse, and this made it worse. It also started sticking. This gradually got better over the next year. When the car was next with a mechanic, he said the clutch lining rivets were loose and relined the clutch. It has been fine since then.

DavidThompson · Posted: Thu Oct 10, 2019 4:00 pm Post subject:

Thanks Paul

I suspect the clutch will need attention sometime soon. It emits a loud squealing when made to work hard, for example if I miss first and try pulling away from a roundabout in second, albeit with a bit of way on. There is no uninduced slip at all.
The judder is still there but seems to have receded, although it may be because I'm getting more used to the car and am more sympathetic with it.

John Murch · Posted: Sat Nov 30, 2019 6:28 am Post subject:

Many years ago I had my cone clutch replaced with a modern borg & beck type, this was because a hill start was almost impossible and even on the flat it was very unpleasant to use.
A well respected expert told me that nothing could be done and did the replacement. The result was very nice. Recently the clutch plate started to break up, and was replaced, but it was noted how bad the wear on the splines was.
This was caused by the chassis flexing and resulting movement between the components. The modern type clutch is not designed to cope with this whereas the original type is.
An inspection of my old cone components revealed that the clutch lining was clearly not quite at the same angle as the cone, the clutch was relined (bonded and riveted) the angle carefully checked and adjusted in a lathe, the fingers also adjusted It now works very nicely.