I've been having a discussion with another forum member about the slipping clutch on a Royal Enfield CO and we're missing something.

We know for instance that cork clutches need to run with oil. The BSA single spring clutch uses a Ferodo friction material which has to be kept oil free. Yet Triumph, Enfield and others use a friction material in segments that also run in oil. My Indian 741 has multi friction rings much like BSA and runs in oil. Anyone got any ideas about this?

The last thing you want on your car clutch is oil!

Ron

email (option): ronpier@talk21.com

It was probably just down to which design was favoured by the designer originally....

It may be in some cases that with leaky primary drives it was considered the supply of oil might be insufficient in all circumstances so best to make it 'dry'..

Alternatively some designers might have felt the cooling effects of oil were beneficial and the problem of sealing the clutch wasn't then an issue so it was better to have it 'wet'...

The M20 clutch is 'dry' but I have made the plates using modern materials that allow it to run 'wet' or 'dry'...

In that case no choice between the two types is required..Maybe something not available to the original designers who had to weigh it up and go for one or the other...Ian

email (option): ian@wright52.plus.com

Ron, I recently have had problems with the bonded clutch plates, on the A10 and now on a rebuilt A7 which made gear changing near impossible, on stripping down the clutch found at least 70% of the pads which were bonded to the plates had disintegrated, the clutch on both machines were running in oil, consequently there was a build up of material between plates which stopped the clutch from separating.
On the M20 I did hear of one chap who got rid of the clutch cover inside the chain case and ran the bike without, I cannot say whether or not he changed the type of plates or not.

Rearguards TTJohn

email (option): Jomichael@aol.com

Thanks for the reply chaps. But Ian the nature of my query is (forgetting the cork plates) why some friction material has to run in oil and why some don't? Ron

email (option): ronpier@talk21.com

The answer to your question, Ron, presumably, is that it is better/simpler(?) to run a clutch in oil for cooling effect and lubrication but clutch lining materials either perform OK bathed in oil and others do not. I am guessing that a car's clutch is similar to a brake drum in that oil kills the friction qualities of the facings...........whereas, cork, for instance is not affected due to its inherent characteristics. My WDG3L has sintered clutch plates and is happy in thin oil......thick oil tends to make them stick together. Or I am talking total bolleaux?

It's a standing joke with Norton that when they introduced their (in)famous 'Oil Bath Chaincase', they continued to run the same clutch as when it operated 'dry'...so they had problems and introduced the tin band round the drum to keep the worst out. Although some got in, it remained in theory a 'dry' clutch.

The original Feridax type bonded inserts don't like running in oil but the level in the chaincase should only just be enough to dip the lower run of the chain anyway.

Modern friction materials run quite happily wet and I don't use a band on the drum.

None of these clutches are going to like an over-filled chaincase.

OK, I've always thought of clutch friction plates to be similar to brake linings and need to run dry. But obviously there are different materials. Cheers Ron

email (option): ronpier@talk21.com

Thanks for all the information guys! This makes it a lot clearer.


Cheers,

Leon