C: Clutch Comet-Burman Stuck Clutch

[AdrianV]

Hi Guys. A big Hello from me Adrian I have just become a member of the club and I have just bought a 1951 Vincent Comet to go with my membership. The bike is full of bells and whistles but now it dosen't go.
The Comet was OK when I rode it back from the shop but now, less than 50 miles later I can't free off the clutch. I have taken the clutch plates out to see if I could find out why they were sticking and was a little surprised at what I found. The clutch drum is a late one, it has 5 bonded plates which I am busy filing off the burs and 6 plain plates, one thick which sits at the back of the drum and another thick one which sits under the spring plate, the other 4 very thin plates sit in-between the bonded plates. The thing is, these thin plates are not flat they are concave. Does this matter? And if it does can you tell me what the part number for these is so I can replace them. Many thanks. Adrian

 

[vibrac]

Part of the clutch display on the vincent spares web shop

 

[chankly bore]

All the plates should be flat. To get slightly more lift with the plain (driven) plates engaged use the thickest plain plate outermost and the second thickest, if there is a difference, innermost. You may have to go four bonded plates and five plain, as the new bonded plates are fairly chunky. The thin plates (old) that I have are 1/32". All plates should slide freely on the clutch hub or in the outer drum, as the case may be. I think the Spares listing is wrong calling up six intermediate or thick plates. If you fit six of either you're likely to have the outermost plates lose engagement, as with five new bonded plates. I can't think why you have burrs on the bonded plates unless some parts have been "manufactured" in Dudwallahbad.

 

[AdrianV]

All the plates should be flat. To get slightly more lift with the plain (driven) plates engaged use the thickest plain plate outermost and the second thickest, if there is a difference, innermost. You may have to go four bonded plates and five plain, as the new bonded plates are fairly chunky. The thin plates (old) that I have are 1/32". All plates should slide freely on the clutch hub or in the outer drum, as the case may be. I think the Spares listing is wrong calling up six intermediate or thick plates. If you fit six of either you're likely to have the outermost plates lose engagement, as with five new bonded plates. I can't think why you have burrs on the bonded plates unless some parts have been "manufactured" in Dudwallahbad.

Thanks for your message. It has been very helpful. I dont think the clutch has done much more than 10K miles, yet it is begning to show signs of wear.

 

[chankly bore]

Where is the wear? Can you photograph it, please?

 

[brian gains]

Io have the plates be concave thr pressure plate must have been tightened down by a gorilla, surprised it would even lift for gear changes.

 

[lee_812d]

Another thing to consider, if you haven't got much lift on the clutch you may need to replace the push rods and the roller, as a small amount of wear on these results in a big difference at the handlebar. I did this and it has transformed my clutch operation. I've made my springs as loose as possible without the clutch slipping up hills. Oil contamination of the plates does not help and can cause them to stick badly - I'm hoping my looser setup will mean less force clamping them together overnight so not glued together by the morning. Time will tell as each time I have it apart I give them a good clean so I now need to wait a few hundred miles to see how it goes.
On another note, I think if the clutch is nice and free you get less of a chance to get the kick start jamming problem because if the teeth do come almost tip to tip causing a jam you can pull in the clutch and the free movement is enough to allow the teeth to engage (seems to be the case at least).

 

[chankly bore]

In my experience it is usually heat that warps plates. Springs (length new 1 and 3/4"), should be about four turns out from fully wound in, then fine adjustment for equal lift. If springs are wound in too tight they usually become coil bound. Have you assembled the roller race on which the clutch basket rides correctly? Thick washer, .160" innermost then 24 rollers 1/4" diameter but only .230" or 6mm, long, then thinner washer .100" thickness. When assembled with the full complement of plates is the outermost steel plate under the pressure plate still engage with the hub when the clutch lever is pulled?

 

[erik]

I can recommend the primary drive oil from Harley Davidson. No sticking clutch plates,soft gear change! Erik

 

[lee_812d]

I'm using the Harley Transmission Formula+. Seems OK so far but I also had it in there before the recent adjustments and it still had issues, hopefully with the adjustments it will be better. Saying that, Harley have two types, the formula+ is the one for my bike so maybe the other would be better in the Vincent (can't tell with Harley stuff because it doesn't say what's in it).
I've got new springs in my clutch and with all the plates in, the outer plate is still engaged with the lever pulled fully in.
I adjusted the springs to make sure of that, and not slip, but I don't know how many turns from fully in they are, something to check next time.