The Clutch on my Comet

[Don Morris]

Picking up the point that Tom Gaynor made regarding heat dissipation from the primary chain. This is important in that, as often quoted a chain is 98% efficient, therefore the other 2% is wasted as heat. You can do the maths yourself by using the bikes bhp as a start.

Quite often people have ruined an enclosed primary chain when it has run dry. Chainspray would work only on a low powered machine such as a veteran/vintage.

I've heard Vincent riders say that their rear chain run hotter when the chain was enclosed.

Reynolds used to say that SAE 20 was suitable for primary drive chains, thicker oil would be pushed aside by the moving chain and would not run back onto and into the chain. Certainly thicker oil gums up the clutch plates.

Len Matthews comment about materials reminded me of Triumph's Neo-Langite clutch friction material. It was common practice for dealers to tie up the clutch lever when displaying new machines, because if you left the clutch engaged for any time you could kickstart with the clutch lever held in.

I've used agricultural ATF in my primary drive for some time with no ill effects. I chose one that was suitable for transmissions with internal brakes, this does not affect clutches so much as modern car oils, no doubt many people will have heard of modern bikes with clutch problems after using synthetic oils.

 

[nkt267]

[/I've used agricultural ATF in my primary drive for some time with no ill effects. I chose one that was suitable for transmissions with internal brakes, this does not affect clutches so much as modern car oils, no doubt many people will have heard of modern bikes with clutch problems after using synthetic oils.
QUOTE]
Makes sense of the fact that my clutch is better since fitting a mainshaft oil seal..John

 

[Gerry Jenkinson]

Any suggestions for the opposite problem, slipping.
The clutch, as it came, to me had cork inserts. Both friction and plain plates were distorted. Corks unevenly swollen.
I have just replaced all the clutch plates with new plates from the Spares Co.
I did a 3 mile trial run up and down a local hill with the primary cover off. Great joy! Silent changes, progressive take up and I couldnt make it slip. No oil leaking from the gearbox or mainshaft.
So I put the primary cover on and added Castrol up to the level plug. Ran it down the hill, stopped to visit a friend. On leaving I couldnt restart as it slipped whilst kicking.
Tightening the springs gives no improvement.
Regarding the lifter mechanism. Operating arm etc are properly set up. Correct clearance at the handlebar lever. The plate lift is about 3/16". The pushrod is divided with a 1/2"x1/4" rod. I dressed the splines and drum slots with a stone, though there was no noticable notching.
Tomorrow I will strip it (again).
I am quite surprised as its a simple clutch, unlike the twin, much the same as others I have done.
Is it an oil / friction material issue?
Gerry Jenkinson

 

[Don Morris]

Well Gerry if you promise not to tell anyone, because of H&S, try draining the oil, what type of oil by the way?, then overfill with petrol. Operate the kickstarter and lift the clutch, this washes off the oil. Do this repeatedly.

If the clutch now works as intended it proves that the setup is OK, and that it is the oil at fault. Try a lighter oil, as previously said ATF or 20 grade.

It would be best to drain out the petrol and refill with oil to protect all inside fairly soon after your trials.

 

[Gerry Jenkinson]

Thanks Don,
Castrol GTX 10/40, which I have used in primary cases on the twin and various Triumphs, Honda's etc with no problem. As I said all was perfect before the oil went in, and I did not overfill.
I will strip it tomorrow for visual checking and give the plates a wash in petrol. I have ATF I can try.
Nice thing about the Comet is the ease of access to the primary drive. Also makes strobing easy with a degree disc on the end of the crankshaft (some blue tack involved).
On H&S I have to be careful as my brother has a degree in the subject and up until two months ago was an inspector for Camden Council. But he is a motorcyclist so would understand, and I'm the eldest!
Gerry

 

[dave g6xnc]

Clutches

Have the chain case off and make sure that the cliutch is lifting squarly if no you can adjust the spring srews or fit new springs. Obviously if the [plate is liftingh at an angle the plates will not free off correctly. I would not try Mobil 1 as this is synthetic and much more "slippery" than std oil
and may cause slipping, also more expensive!. Try ATF if the problem persists or castrolite sae 10/20. These are old chestnuts but these are old bikes!.
dave gs. Easier clutches top get at than BMW's!.

 

[Tom Gaynor]

Slipping clutches

Because of a mod by a previous owner, my twin runs a fully wet modern multiplate clutch. In trying to sort a different problem (reluctance to free from cold) I've been experimenting with chaincase oil over several months. (But not this month: there's snow lying outside...)
Although I accept the argument that Mobil1 ought to be more prone to slip being super-duper new technology (with price to match) in practice it has proved no different from ATF or straight 0-40 which I've also tried. Since Mobil1 makes the clutch easier to free than anything else did, I used it all last year. If it was going to slip it had it's chance on the IoM lap, but it didn't.
I don't argue about the price: I'd be cheaper using Chanel No 5.......

 

[bengunnhrd]

Clutches

I have a V3 clutch in a Rapide which has been fine since the day it was fitted, and one in a Shadow with which i have had a number of problems, slipping under load in 2nd gear which made it squeal like a stuck pig, at first i put washers under the springs which helped, then a new set of plates containing one that was dished which seems to have cured the problem (how it works i have not got a clue). Another issue was trying to select neutral when the engine was hot, tried everything, eventually i replaced part of the clutch rod with a mini exhaust valve, the large diameter head lifts the outer plate cleanly this has made it much better.

 

[nkt267]

The clutch, as it came, to me had cork inserts.[/QUOTE

Have you changed the springs as i believe that cork and Ferodo type linings use different springs.
I got my springs at Stafford from the man with the large mobile stand,can't remember his name although he is well known,and he lists different strength springs for cork or synthetic linings.Also you are using 5 friction plates not 4 aren't you,as mine slipped with 4 but only when lubricated.John

 

[Tom Gaynor]

V3 clutch

Where did you get the dished plate from?
The mini exhaust valve dodge first appeared in FYO, probably 20 years ago. I've never had to use it, but it's interesting to see that it is still effective!