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The Clutch on my Comet

Graham Smith

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Anyone who knows me will tell you that I'm not the most mechanically minded person in the world, but I'm willing to give most things a go.

On my Comet, whenever I put it in gear, it's a real 'crunch' of a gear change. Likewise, when going from 1st to 2nd, the same thing.

From 2nd to 3rd OK and 3rd to 4th OK.

I've tried adjusting it, but that doesn't seem to make any difference.

Someone has suggested that the clutch plates could be getting stuck together, but this is now getting out of my capabilities.

Does anyone have any other suggestions on what I can do to make a nice quiet/smooth gear change?
 

Len Matthews

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VOC Member
Graham, it might be worth checking your handlebar lever. It depends on the distance between the pivot screw and the nipple hole how much pull you get on the cable. Can't remember the dimensions off hand but it follows that the further away the nipple hole is away from the pivot, the greater movement on the cable which may help the clutch to clear and allow crunch-free engagement.:)
 

BlackLightning998

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VOC Member
How about selling it......

Graham,

How about selling it and buying another one, that often works!!!

Stuart

PS - Oh, and did I mention a I know a chap that would love to own one as nice as yours.........just in passing.........
 

Hugo Myatt

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All my suggestions are empirical as I have no technical expertise at all. I find that any oil more than 30 weight in the chaincase causes the clutch plates to stick. Some owners use Automatic Transmission Fluid but it did not work for me. Also check the oil level in the chaincase. Some chaincases fill up with engine oil. Too high a level seems to cause sticking plates. The other problem I have had is the push rod wearing concave at the gearbox end where it bears against the ball bearing and so reducing the length of the push rod. If the Comet is unused for any length of time the plates seem to stick together. At one time I used to tie the clutch lever back to the handlebars when not in use but over time this caused weakened springs and clutch slip.
 

Comet Rider

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Burman/Comet clutch

Hi Graham,

Just my two pennies worth.

1/ Is it just when the engine is cold, or does it happen all the time?
2/ Try Mobil 1 in the chaincase (it worked for me on both the Burman and the Conways clutch)
3/ At the risk of purists try a Honda lever assembly on the bars, as this gives slightly better lift.:eek:
4/ Finaly do you have a lot of end float in the main shaft, which can lead to loss of movement?:eek:

Neil:D
 

Pete Appleton

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VOC Forum Administrator
Looking on the bright side

Graham
My Comet started doing just this just before the clutch basket self destructed.
If the crunching is something that you have always had then the comments about increasing cable movement and trying different potions in the primary case are valid.
If this is a new manifestation then you are looking for something that is wearing out/ breaking up, in which case it is worth pulling the primary cover off and checking the clutch basket for cracks..... There is nothing on the telly tonight anyway you might as well spend the evening in the shed.
 

Tom Gaynor

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Clutches

If one takes the chaincase cover off and observes what happens when the lever is pulled, invariably one finds that the pressure plate lifts clear, but the plates remain in a single block. ALMOST AS THOUGH THEY WERE STUCK TOGETHER. Obtaining more lift increases the pressure plate clearance. The plates however remain in a single block.
My Manx, with dry clutch, has about 1/32" lift. If I fail to strip and dry it after a wet meeting, the pressure plate will lift (it has no cover, so it isn't difficult to see) but the plates remain stuck together.
What I take this to mean is that even if the pressure plate is lifted 30 feet away from the bike, it won't make a blind bit of difference, because the problem is plate "stiction". On the Norton the cure is to part the plates one by one, dry everything off, remove any rust, and put back together again.
On my twin (with V3 clutch) my experiments indicate that Mobil1 0-something) gives minimum stiction - less than ATF, or the initial straight 40. Once the plates have freed, the clutch is everything I could wish for.
More lift isn't going to help. IMHO, the only difference using a lever with worse leverage (= better lift) is to make an already light clutch, slightly heavier.
I'm open to correction.
 

Pete Appleton

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Prepare to be corrected

IMHO, the only difference using a lever with worse leverage (= better lift) is to make an already light clutch, slightly heavier.
I'm open to correction.

Tom
I agree with you that more lift will not solve the problem of stuck plates. BUT !! I found that with the multiplate setup on my twin, as the plates heated up during stop start work in heavy traffic they were either swelling or distorting and feeding the clutch in to such an extent that the only way to stop the bike was to stall the engine, amid much swearing, and wait for everything to cool down. Increasing the lever pivot length to 1 1/8" has cured this.
Pete
 

nkt267

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VOC Member
I saw something on another site for bikes with Burman clutches.they advise running the clutch case DRY:eek: and using spray chain grease on the primary chain, to stop the plates sticking.A reference to the Marston Sunbeam parts list for 1932 suggests no lubrication in the primary if Ferodo inserts are used.Does this suggest that non cork material might be prone to sticking if they are lubricated with oil (wrong oil?) The set of plates I replaced after the Manx showed that oil had got on to them via the drive side mains and they were a mess. The noisy gear change was caused by that and, as Tom says, the basket had cracked and spread to such an extent the top plate tang had jammed between 2 slots on the basket.Pulling away was almost as exciting as Charlie Boorman's wheelies(nearly lost the wife once):D.
The other part of the clutch mechanism that seems to be overlooked is the operating arm in the case.If the small halfmoon section that bears on the rod pin is worn away then you get less lift as well..John
 

Len Matthews

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VOC Member
This business of clutch plates sticking together after a period is nothing new. I recall a Comet where the plates were stuck solid even after a relatively short spell of idleness. The problem stemmed from the grade of friction material. Once these plates were changed for a set supplied by one of our leading spares suppliers the difficulty diappeared and crunchy 1st gear engagement became just a memory.
 

Tom Gaynor

Well Known and Active Website User
VOC Member
Clutches

I've had no problems with the V3 except for the first "clutch operation" of the day, and that includes runs including about 2 miles of threading traffic. I know (because I looked at the lift issue when trying to cure what I now think is stiction) that my 1951 52,000 mile twin has about 3/32" of lift with what I am sure are the original parts.
I have a friend who cured oil leaking out of a Rudge chaincase, but not before it had leaked into the (dry) clutch by draining the case, cleaning the clutch, and using chain lube spray thereafter, and I have done that myself. I'd be leery however about trying it on a twin, or even a Comet used for long runs. I've read that the chaincase oil plays a significant part in dissipating heat from the chain, and find the argument persuasive. I therefore bit the bullet, cured the leaks both out of the chaincase and into the clutch, and the Rudge runs on oil.
Stuart Towner offers a "wet or dry" Rudge clutch conversion so perhaps any day now he'll stagger blinking from all that midnight oil smoke out of his laboratory with a similar Comet conversion........
 

tim welsh

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Non-VOC Member
This also happened to me just before the clutch basket did the "splits", same as Pete's, so it would be worth checking- I think you can see the basket well enough through the filler cap. See my thread "Burman Clutch". Most recommended the Conways replacement if that is the problem. I've run it in ATF for a couple of years now with no sticking problems.
Tim
 
Last edited:

dave g6xnc

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Non-VOC Member
Clutchs.

An old dodge before starting the bike pull in the clutch and kick it over a few times, this will of course free up the cluth plates. If it tries to turn the engine over with the clutch out you have got problems.
dave gs.
 

Tom Gaynor

Well Known and Active Website User
VOC Member
Clutch problems

Before I changed the oil in the chaincase to Mobil1 I could easily start the bike (a twin) with the clutch pulled in. If I did get the clutch to unstick by kicking, it STILL went into first with a hellish crunch. So I really had a problem.......
 

Tom Gaynor

Well Known and Active Website User
VOC Member
Clutches on old bikes

I think Fraser has hit the spot. A conclusion I came to after going from close ratio boxes to road ratio boxes was that road bikes before, say, the 50's were intended to be ridden in top, with the other three gears used for getting to top, or for extreme conditions - steep hills or heavy traffic. I therefore adjusted my attitude, and stopped trying to make lighting changes, "flicking it down one" because the ratios were too far apart anyway. The contrast between my Norton with a six-speed Shaffleitner, and, say, the Vincent, is stark. The Shadow has a very nice high first, which means I don't have to come to a virtual stop before engaging it as I do with another (1938) bike. But changing gear on the Vin is a three step process, whereas with a six-speeder I just press the pedal, clutch optional.
 

Graham Smith

Well Known and Active Website User
VOC Member
VOC Forum Administrator
VOC Forum Moderator
Anyone who knows me will tell you that I'm not the most mechanically minded person in the world, but I'm willing to give most things a go.

On my Comet, whenever I put it in gear, it's a real 'crunch' of a gear change. Likewise, when going from 1st to 2nd, the same thing.

From 2nd to 3rd OK and 3rd to 4th OK.

I've tried adjusting it, but that doesn't seem to make any difference.

Someone has suggested that the clutch plates could be getting stuck together, but this is now getting out of my capabilities.

Does anyone have any other suggestions on what I can do to make a nice quiet/smooth gear change?

My Executive Committee colleague and thoroughly good bloke Dick Wheeldon kindly agreed to have a look at my Comet's clutch, and we discovered there weren't enough friction plates!

Apart from that, we took the other friction plates and gave them a good clean in white spirit, as they were completely stuck together. They seem fine now.

I'm planning on going out for a spin tomorrow, so if anyone sees a Comet broken down at the side of the road in the Orpington area, please stop and offer me some assistance!:)
 

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