[Brian Petheram]

Hi Paul,

thanks for the clarification - I was afraid I was missing a thrust washer or something; the parts book is quite hard to follow. I will go ahead and get the clutch recorked as those on the chainwheel are worn unevenly front to back, and hopefully that will sort things.

I did do a forum search on "clutch" earlier but couldn't find the discussion on chainwheel float, but as it seems I have all the right bits I'm sure it will be ok. I guess it must work because the chainwheel is held in place by spring pressure when under load and the chain sprocket only wobbles a millimetre or so when the clutch is lifted and thus the load on the chain is removed. It has lasted 92 years now so it will see me out!

cheers

Brian

[phutton]

The  pitch basket cum chain wheel does indeed float on the spigot of the backplate when the clutch is lifted. The projection of the corks in the basket should be the same front and rear.

There was quite a lot of correspondence  on the Forum on this issue a few years ago. Try the search facility on here to find it.

[Brian Petheram]

Stripped the clutch right down now and my findings have brought me right back to the original topic of the thread - I was slightly guilty about my posts diverting it!

Now I have removed the backplate and chainwheel (didn't even realise they were separate) it initially looked like the chain line is determined by the thickness of the corks in the chain wheel as it is free to slide on the boss of the backplate. Also there is 1.5mm of the boss protruding through the chainwheel which means that the splined centre goes up against the boss. If the chainwheel corks were thicker then the splined centre would go up against the chainwheel instead. The corks in the chainwheel are almost flush at the back but are a bit proud at the front.

Only way I can see this arrangement making sense is if the spring pressure always forces the corks in the chainwheel forward so that the chainwheel is always up against the backplate and thus the splined centre always abuts the backplate boss rather than the chainwheel. This would keep the chain line consistent. Writing this reply has actually helped me get this straight in my head as when the spring and plates are out the chainwheel moves back and forth which feels so wrong!

I would appreciate any feedback on whether I have this right as my confidence is rather low on this! Plan is to just clean it all up and reassemble as is but if you think I need to recork or check anything else then please say so.

cheers
Brian

[Brian Petheram]

Thanks for the further replies. I put what I believed to be a minimal amount of oil in - just enough for the chain to dip in and then presumably throw it around.
The manual is rather vague about the amount of oil required. In the lubrication chapter on page 14 it advises that the engine should be running when the front chain is lubricated "so that each link gets its share". It also says that the chain gets "a certain amount of lubrication through the cush-drive and from the gearbox". It recommends Castrol C or XL and also states that Castrol R "would render the clutch inoperative"!
In the clutch section on page 36 it says " a certain amount of oil is no disadvantage.... it prevents the corks from wearing". However it also says that if too much oil gets in the chaincase should be washed out with paraffin with the engine running and whilst operating the clutch. The chain should then be lubricated "with a little engine oil".
I take the point about the corks burning but possibly there will be enough random leakage via the gearbox and cush drive to prevent that. I would be very interested in owners' current expeiences using modern oils or alternative friction materials. Given that it's a 1927 Model 5 Longstroke I can live with a little clutch slip at 70 mph.
Cheers
Brian

[wessex_man]

It's not a good idea to run a cork clutch dry. You will burn it out. We just use a light oil. it's more important to adjust the clutch properly follow works instructions and you won't go far wrong.

[singleminded]

How much oil did you put in?. just over the chain or a lot more?
I had problems with the 6 spring clutch on my brother in laws 9A, I could not stop it slipping.
It had 'Ferodo' type linings and slipped slightly even after I sanded the plates as flat as i dare..
The steel plates were flat but i suspect that the rear plate that the ratchet fits on, you may not have this type of clutch, was not flat..
I found that out on my own 9A , and I suspect it would be less of a problem with corks as they are softer and mould themselves to the plates a little.
My cork clutch only slips a little at 70 mph. The new modern material I fitted is a lot better, i was getting 'pulsing' take up on releasing the clutch..

[Brian Petheram]

Hi Klaudius, many thanks for your helpful reply and please don't feel you need to apologise for your English - mein Deutsch ist schrecklich and mon Francais c'est execrable!

A glitch in the withdrawal mechanism is an interesting idea and I will certainly check it out. I did previously dismantle the clutch to clean the plates etc. - they were all straight and the corks were in good order so I reassembled and all was well using a light spring pressure until I replaced the case and put some oil (Automatic Transmission Fluid) in. I have used this on Triumph clutches with success but maybe it doesn't work with cork. With the oil in I have had to greatly increase the spring pressure - although not as much as the previous owner!
Regards,

Brian

[klaudius]

Hello. This problem I had synonymous. Please check the expression mechanism. I think it is not because of corks or dennen operating with oil or without. With you it seems to be so that the clutch when releasing the lever is not completely disengaged. Most of the time it is due to wear of the storage and its push rod. The whole thing in connection with not kerk screwing the pressure plate spring causes the problem. A rather trivial problem of eliminating (as with me) much time and annoying costs.Check if plates, corks etc. are straight. It's best to remove everything and clean it. Takes something but prevents it from doing offters as a dear. Greeting klaudius. P.S. Yes my english is horrible.

[Brian Petheram]

I'm interested in this topic as my single spring clutch is slipping occasionally when using the kickstart. I have dismantled the clutch (and am about to do so again) - the corks in mine are proud of the plate but nowhere near 3.8mm. Surely as long as all the corks are proud of the plate and even, the actual amount of protrusion should not affect the working of the clutch? Or am I missing something?

My current thinking is that the ATF I'm using in the chaincase is the problem as it didn't slip when kicking it over dry with much less spring pressure (I have fitted a new spring). I'm tempted to either run the chaincase dry and use chain lube on the chain (would this lead to clutch bearing problems?), or get the plates relined with rings of modern oil proof friction material as I can't see the point of replacing the corks with more corks. Having said that, cork clutches must have worked when new so maybe I just need to wind the spring adjuster up tighter and put up with a heavy clutch action. The previous owner had the spring done up so tight that I needed a two foot long bar and socket to get the adjuster nut off so it's a pre existing problem.

All thoughts and suggestions welcome.

Brian

[Winold]

Hi Claudius,

Awesome, thanks!

Cheers, Winold

[klaudius]

Hello. I meant --- 3.8mm + thickness clutch plate + 3.8mm
The cork stands on each side 3,8 mm above the plate after pressing.
Claudius

[Winold]

Hi Claudius,

Thanks for your reply and useful tips and photos!

Just to be sure.. For the length of the cork, do you mean;
3,8mm + 3,8mm = 7,6mm
Or
3,8mm + thickness clutch plate
Or
3,8mm + thickness clutch plate + 3,8mm
?

Thanks!

Kind regards Winold

[klaudius]

Hello. I press the corks myself in home-made primitive press. The uniform distance after pressing can be precisely adjusted by the discs. Cork I buy ready. Are a little bigger than the plate. After softening 30 min / 60 degrees water for me are 3.8 mm front and rear. In the water I add some dripping emulsion oil, which prevents rusting of the plate with dry cork. Please excuse my english. I hang up some photos to pretend better. Have fun crafting. Claudius

[Winold]

Hello everyone,

Is there someone who could advise me what the correct thickness of cork should be in the sprocket plate and in the clutch plate? The only information I can find is about a 6 spring clutch with more then two plates. In the 4 1/4hp instructions manual is said that the outer clutch plate should be fitted with "raised side outwards". I understand this as the cork is not central in the plate, but fitted so that it is longer on the outside.

Also, when recorking, does it matter in what direction the corks are cut out of the bark? I could imagine that the cork could be stronger and more resistant to wear when the disks are cut out in the length of the tree.

Hope anyone can help, thanks in advance!

Kind regards Winold