Clutch material

[k. rogers]

Has anyone had occasion to source a suitable replacement material for the vintage cone clutch? It was apparently an asbestos rope reinforced with brass wire originally.

[k. rogers]

Actually, found lots of pics and Info on the subject on here from messrs Bangham and Ellison. I think I've established I can use 5mm Kevlar rope in place of the original asbestos, but I need to make sure I get the correct one and from the right place.

[ChrisE]

I’ll post up some pics later today and some information.

[ChrisE]

Hi there,

I changed my clutch in June 2019. My car is a 1929 Long Four. The reason I changed the clutch rope was the old clutch had worn out and the cone was “bottoming” in the flywheel and slipping. The ‘rope’ had worn out.
I should preface this by saying if your rope is really old, pre-2000 (when sale of asbestos was banned by law) then you should suspect it may contain asbestos. My sensible precautions were to unwind the old rope from the frame in the outside, put it all in a bin liner, seal it and dispose of it carefully. Once that has gone, there should of course be no asbestos risk. Mine was all pretty oily and bound up so very, very little risk of loose fibres anyway.
I tried all sorts of ropes and fibres with little success until I found this Kevlar rope (see images). It cost about £10 and is 6.5mm and is long enough to do two cars.
The first attempt was a bit ‘big’ and the clutch didn’t go into the flywheel deep enough. Then the next one was too small, and this went on for several attempts until I got this 6.5mm rope. Even then I had to manipulate it to make it ‘just right’. What is did is place the rope on the workshop floor, tap it gently until it was oval, along the entire length, so it was probably 4-5mm thick and 7-8mm wide in section. To be fair, it took a bit of messing to get this just right. Then winding on is simple and putting the new clutch back in is easy. Crucially when the clutch is in, and springs tightened, the aluminium clutch wheel was about 1mm proud of the flywheel. This is probably the bit that takes a bit of messing about to get it right.
My rope has been on for 4 years now and shows no sign of wear. We live in a very hilly area and probably drive 20+ days a year including some long 4 hour journeys and still as good as new. I’ve pasted some photos below which might help, including one showing the rope supplier (I got mine through Ebay).
Some of the photos are where the rope is “too thick” that’s when the whole clutch is stuck out too far but then you can see the ones where it sits ‘just right’.

Finally some people have had the aluminium clutch skimmed, to lose all the groves then had a bespoke, cone shaped lining, like a brake shoe lining, bonded or riveted onto the clutch. That of course is a permanent change and once the grooves are gone, they are gone forever. I’m not in favour of such permanent changes, or improvements. If I wanted such a car I can sell the Jowett and buy a Mondeo! I’d also be wary that a lining is more fierce than the rope and as a modern clutch plate wears the cover plate of a modern car, a lining will eventually wear the flywheel much more than rope will. Good luck to those people when they need to find a replacement flywheel!

[Forumadmin]

Excellent contribution!

[k. rogers]

Thank you very much for that information Chris.

[Dhbangham]

Another one to agree, a really useful post. Thanks.

[k. rogers]

Good evening Chris and Daniel. Now that it has been about 18 months or so since you both replaced your clutch material with Kevlar rope, would you kindly update me with how successful this material is as a replacement for the original asbestos please. I am about to replace the rope in my vintage and would really value your input!

[ChrisE]

Hi Ken,

I’m afraid it’s all pretty boring! The clutch has worked flawlessly ever since rewound it with Kevlar rope.

There was one time early on, when a couple of strands (not a couple of ropes) came loose and flew of, it looked like a large spiders web of kevlar beneath the floor-board, but that just cleaned off and made no difference to the performance. No real work was required.

I’ve never had to drip oil of petrol on the clutch to reduce or increase the friction. It seems to be just right and keep that way (unlike a friend’s 1927 that still has the asbestos rope on and can be very bity, needing a drop of oil to make the clutch practically usable)

You may have seen on here that I took off the gearbox (not the clutch) a number of times and rebuilt that so have had a good chance to closely inspect the clutch/flywheel in situ. It doesn’t seem to have ‘sunk in’ at all indicating that there hasn’t been any appreciable wear so that’s good too.

I’m guessing that we do about 1000-1500 miles a year but the terrain around here is very, very hilly so it does get a decent amount of clutch-use.

Chris

[Dhbangham]

Thanks Chris for the update, very encouraging.
I have nothing to add to Chris's report as I ended up swapping out one cone for another, and I am still awaiting to putting my kevlar rope on the original. This has been delayed as I have only just finished a very successful Bowel cancer treatment on the NHS.

[Chris Spencer]

Daniel - Vintage clutches aside - Really nice to read your last sentence on the above post - hope things continue to head in all the right directions - regards Chris

[k. rogers]

Daniel, I'm so sorry to hear about your health problem, but delighted to hear the treatment has gone well.
Chris, that's all I wanted to hear about the Kevlar. That is the route I will go down. Thank you both for all your input.

[Cyclecars]

Super helpful for me, too! Thank you!

I have a question about a slipping clutch. Is there a way to tell when the three nuts are properly adjusted. This silly question is because I do not know the condition of the clutch from what would normally be driving experience. I have only driven the car a few miles so far since acquiring it. The car had a new clutch placed on it before I acquired it. However, it has slipped since I first started driving it. I do not want to pull everything yet since I presume that the contact materials are fresh. If I overfilled the gear case with too much oil, would this taint the clutch surface? I have read that I can/should adjust (tighten) tension of the clutch using the nuts, obviously. But since I am new to driving this new clutch, I do not know how much and if perhaps it was my fault since I had to fill the gear box and may have over filled it initially.

I know this is a rambling question, but I am trying to solve this without pulling the engine out and doing a complete rebuild (yet).

I am open to thoughts and outright criticism if my ignorance makes that necessary.

[k. rogers]

I had the same problem quite regularly on mine since I bought it! I delayed the inevitable replacement of the lining material by using Fullers Earth between the lining and the housing to absorb any oil on the surface. This worked for some time, usually months until it started slipping again. Over filling the gearbox will possibly result in oil being thrown out where you don't want it. I have learnt, only in the last year, that we should be using 40sae oil in the box which should help somewhat in keeping the oil in!
I have now purchased some Kevlar rope to replace the original lining which I'm sure is now saturated by years of oil ingress.

[k. rogers]

I forgot to mention the adjustment springs. There is no correct setting for these, but generally I should think screw in the nuts until there is about 1/2 inch of thread showing to begin with. The problem comes if you carry on screwing the nuts in much further, you then end up with very little travel, resulting in the clutch not disengaging sufficiently.