Cone Clutch Noise

Malcolm J Crump · Posted: Fri Nov 06, 2015 7:48 am Post subject: Cone Clutch Noise

I have recently had my cone relined and purchased a new outer ring. I've also renewed the smaller front bearing. The fingers of the outer ring are 1mm (0.040") proud rather than 3/64" but I'm assured this is ok. The ends and edges have been chamfered to the best of my ability as described in the Technical Facts. The clutch works perfectly well but makes a horrible "scraping" noise at the point of engagement. The front edge of the cone is not fouling the rear of the flywheel and the clutch stop material is almost new and seems to be doing its job satisfactorily.

I can only conclude that the scraping noise is caused by the friction material rubbing on the fingers and I'm wondering if the profile of my chamfering is somehow to blame. I have taken advice from two long standing and very experienced BDC members and the consensus of opinion seems to be to "live with it until it wears in".

Any views or suggestions to help me to eradicae this noise would be most welcome.
Malcolm Crump (1924 3 litre Speed Model)

John Murch · Posted: Fri Nov 06, 2015 5:08 pm Post subject:

Malcolm, i was hoping to see you get an intelligent reply to your post, but I suspect most of us with cone clutches (or in my case I converted to a plate clutch after I just could not get it right), are rather relieved when they work nicely and don't slip.
There have been a number of posting on the subject of cones, have you done a forum search?
I suspect that I would also be in the live with it a while and hope it goes away camp.
Have you been able to observe what is happening from under the car, perhaps a suitably positioned camera and a video of the clutch in action could reveal a clue.
Best of luck
John

Malcolm J Crump · Posted: Fri Nov 06, 2015 5:56 pm Post subject:

Thank you John, slipping is not a problem, perhaps beause I have the stronger (round section) spring. I have had perfectly effective and quiet cone clutches in the past but which were all well worn. I sometimes wonder if the "fingers" design is too clever by half and whether I'd be better to drastically reduce the extent to which they are proud of the inner surface of the outer ring.

However I'll wait to see if a BDC sage can help me with some wisdom from past experience.

Regards

Malcolm

Chris Card · Guest

I seem to remember this happening when I had mine relined some years ago - it gradually stopped and I think it was something to do with the surface of the lining that had to wear away.

Chris

Malcolm J Crump · Posted: Wed Nov 11, 2015 10:05 am Post subject:

Thank you Chris,
Your expereience is in line with the sage advice I've received to date and the conclusion that I've reached so far. What puzzles me is that more members haven't written in with this problem if its caused by the surface of the lining My clutch was relined by a well-known firm that has done literally hundreds of Bentley cone clutches over the years. My lining has got small brass "flecks"embedded in it.
Regards Malcolm