Burman clutch

derek

Well Known and Active Forum User
VOC Member
I have a Burman clutch on the Comet with 5 friction plates. all parts are in as new condition, there is no notching of basket or hub slots, all pressure and friction plates are new from VOC spares Co. It is correctly adjusted and plates separate squarely. It runs with engine oil in the primary case at correct level. However, when left for a period in the garage the plates stick together and are difficult to free. I put a tie around the clutch lever to keep the plates separated when left for long periods, then all is OK. Also when riding, although the clutch works OK, the plates still tend to stick. Anyone got any idea why? is it the friction material, could a different lubricant be beneficial?
 

Hugo Myatt

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VOC Member
I have a Burman clutch on the Comet with 5 friction plates. all parts are in as new condition, there is no notching of basket or hub slots, all pressure and friction plates are new from VOC spares Co. It is correctly adjusted and plates separate squarely. It runs with engine oil in the primary case at correct level. However, when left for a period in the garage the plates stick together and are difficult to free. I put a tie around the clutch lever to keep the plates separated when left for long periods, then all is OK. Also when riding, although the clutch works OK, the plates still tend to stick. Anyone got any idea why? is it the friction material, could a different lubricant be beneficial?

It's a common problem. Some people swear by ATF (automatic transmission fluid) although it did not make much difference with mine. Thinner oil, e.g. 20 weight probably helps but is eventually contaminated by engine oil seeping through the drive side main bearings. Just a word of warning about tieing the clutch lever back. I used to do this but found the clutch springs quickly tired causing clutch slip. Although I never start the bike on the stand (centre stand in my case) I do free the clutch whilst it's on the stand. I work the clutch lever in and out whilst applying pressure to the kickstart. This will normally free the clutch plates after a few goes. Anyone with a foolproof solution?
 

Bill Thomas

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VOC Member
Like Hugo, Says, Most do it, I just put it in gear and rock it back and forth, Hope it don't start !! Cheers Bill
 

vibrac

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VOC Member
Might be some information on the AJS-Matchless forum they too are often cursed with the same bag of mild steel shavings and cork. I have a few shelves of Burman clutch parts but the chain wheels all went to Honda conversions and the rest are Bob Newby belt drive refugees.
Memory fades and its raining so I wont look which is standard, but I believe an improvement was suggested years ago where its possible to reverse the driver and driven functions with different plates if the tonged ones are friction then use plain there and the hub driven ones become friction (or the other way:confused:)
 

Howard

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VOC Member
The answer is don't "leave it for a period in the garage"!:)
Mine does the same, I've just come to the conclusion you have to accept it.
I remember having a clutch (probably BSA or Ariel) that had indented steel plates, I assume the idea was to stop suction or stiction or whatever the technical term is.

H
 

nkt267

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VOC Member
I found that there are some plates with a 'white-ish' type of friction material anfd they stick quite badly.
I never had too much of a problem using a very thin oil in the primary side..Even the Honda clutch needs to be checked for free movement before I start it..ie stick it in gear,pull in the clutch and operate the kickstart..John
 

derek

Well Known and Active Forum User
VOC Member
I am more concerned with the clutch plates sticking while riding and changing gear, than when the bake is inactive. From the replies to my original post, it can only be concluded that the friction material used is not fit for purpose in a wet clutch! These problems never occurred with material used back in the 1950/60s (I was their). I would have thought that with all of the technical knowledge within the club membership and the power and connections that the VOC spares company have within the industry that a correct fit for purpose friction material could be found. After all this problem does not exist with modern bike clutches (Honda etc) ! Why! Derek.
 

Hugo Myatt

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VOC Member
I am more concerned with the clutch plates sticking while riding and changing gear, than when the bake is inactive. From the replies to my original post, it can only be concluded that the friction material used is not fit for purpose in a wet clutch! These problems never occurred with material used back in the 1950/60s (I was their). I would have thought that with all of the technical knowledge within the club membership and the power and connections that the VOC spares company have within the industry that a correct fit for purpose friction material could be found. After all this problem does not exist with modern bike clutches (Honda etc) ! Why! Derek.

Some time ago someone did some research on grades of Burman clutch friction material and concluded that the original specification for Vincent clutches was the same as that for Ariel clutches, a dry clutch, and not the grade used for wet clutches, e.g. Panther, etc. If true this was obviously an error in the listing and would explain a lot.
 

Howard

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VOC Member
"Fit for purpose" is a very difficult thing to define! How many types of plates should the VOCSC stock? Vincents nowadays aren't used as the everyday transport they were intended for, they're trailered to shows, used occasionally, only used when the sun shines (hope that's not racist, after the recent dj controversy), raced, used for commuting(?), long distance touring etc etc ................. sometimes we have to go for a one size fits all. I haven't seen my clutch plates recently, but I have a sneaky suspicion they've got cork inserts.

Just a thought, clunky gear changes aren't always down to the clutch.

H
 

derek

Well Known and Active Forum User
VOC Member
Fit for purpose means that the item/product should be expected to perform its function correctly , ie. connect/disengage drive as and when required when operating lever is pulled/released, smoothly and cleanly. Cork inserts are no longer available. I do not expect the spares company to stock numerous clutch plates or other items, but with their interface with the producers I do expect an item to work correctly for a standard machine! If you only show a machine does it need a clutch:
 
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