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C: Clutch Twin clutch drag

sharkey

Website User
VOC Member
When operating the kickstart lever with engine stopped and the clutch pulled in there is no clutch drag but when operating the clutch having already applied pressure to the k/s lever there is some drag. C23 is not lifting absolutely square but has a minimum clearance of 25 rising to 40 thou' around the plates. All springs relatively new, are of equal length and free to move within their cups.
There is at least 25 thou' clearance between the clutch shoes and drum; plungers C11/1 are free and butting against the correct C14 pins but those pins have C16 sleeves besides the 3 in the normal C13 locations. The plunger springs are exerting reasonable pressure.
There is approx 10 thou' clearance at C19 shim.
I would appreciate thoughts on the cause of the drag and how it might be eliminated?
 

sharkey

Website User
VOC Member
Bad terminology by me re C17 bush and C20 nut. I meant the diametrical fit between C20 o/d and C17 i/d.
C13 rotates easily but may be tilting due to excessive diametrical clearance?
 
Last edited:

Bill Thomas

Well Known and Active Website User
VOC Member
Sounds to me like sticking plungers or not the right strength,
It's funny, I have seen the strong and the weak springs both way round in Books,
I rode a bike once that was wrong, But on the road was OK !!,
So within reason it don't matter.
If the bushes in the big wheel are loose, It will allow the drum to move ,
So the clearance will not be what you thought ?,
There is a certain amount of throw out with the shoes,
If changing at higher rev's.
 

Mikethebike

Active Website User
VOC Member
When operating the kickstart lever with engine stopped and the clutch pulled in there is no clutch drag but when operating the clutch having already applied pressure to the k/s lever there is some drag. C23 is not lifting absolutely square but has a minimum clearance of 25 rising to 40 thou' around the plates. All springs relatively new, are of equal length and free to move within their cups.
There is at least 25 thou' clearance between the clutch shoes and drum; plungers C11/1 are free and butting against the correct C14 pins but those pins have C16 sleeves besides the 3 in the normal C13 locations. The plunger springs are exerting reasonable pressure.
There is approx 10 thou' clearance at C19 shim.
I would appreciate thoughts on the cause of the drag and how it might be eliminated?
Hi Sharkey. Even light pressure on the kickstart will engage the clutch shoes with the drum, depressing the C7/1 plunger. If the clutch is then lifted, C13 should be rotated forward by the plunger spring, releasing the shoes. If the spring is weak, there is some friction in the various pivots and bearings, or the plates drag, this might not be happening. It should be possible to get the plate swash down to about 0.010".
 

stu spalding

Well Known and Active Website User
VOC Member
Hi Sharkey, try typing "dummy clutch centre" into [search] and combine that info with the articles in MPHs 820 and 821. The dummy centre is essential for taking the guesswork out of setting up the twin clutch. It has been suggested that, in view of the amount of time, effort and money involved, that it's better to buy new shoes, but once old ones have been bushed and sleeved with bronze they'll far outlast the new. Cheers, Stu.
 

paw99

Active Website User
VOC Member
Not an answer but an associated question...how much runout (wobble) is ok on clutch shaft?
I cannot get even lifting, and wonder if bent clutch shaft would give this.
Have measured all clutch springs, approx equal. When clutch disengaged and rotated can see sideways movement of friction disc.
 

Bill Thomas

Well Known and Active Website User
VOC Member
When loose there is nothing to hold the friction disc ?, So it can flop about ?,
Have you got one of T.T. s Bearing mod , To lift the plate square ?,
You can get one off Him or through the Club Spares.
Cheers Bill.
 

paw99

Active Website User
VOC Member
When loose there is nothing to hold the friction disc ?, So it can flop about ?,
Have you got one of T.T. s Bearing mod , To lift the plate square ?,
You can get one off Him or through the Club Spares.
Cheers Bill.
Thanks Bill, that is great, saves me (again) from trying to attain the impossible. One by one all my little probs are being resolved by this brill forum
Cheers Peter
 

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