Snatchy clutch or Kangaroo petrol?

Chris Launders

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What should the lengths of the C14,s and C15,s be, my clutch is quite heavy compared to any others I have tried and wonder if a previous owner shortened them, it was raced sometimes in it's youth, I have tried a new cable and fitted new C29 springs and anything else I can think of. Other than being heavy it works brilliantly.
Chris.
 

Bill Thomas

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Hello Chris, If you have the 5 eared plate, With the mod' of bonded sides on to a steel plate, I have found them to be wider, Which makes for a heavy clutch, I found if I use a new cable with a nylon ? covered inner, It is a bit better, Cheers Bill.
 

nkt267

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Put the clutch back together today,popped the bike out of the garage to check the clutch properly.AGHHHH not much different,a bit better but not right.
I still had about a 1/16th inch clearance between the C7 plunger and the carrier pin it is supposed to bear against or at least the diagram posted here looks like it should.
So out with the plunger and skim 40 thou off the shoulder to let the plunger stick out a bit more.Reassembled and the play has now gone.
OI dinners on the table says 'she who must be obeyed'( if I don't listen she won't),so tried it in the garage with the front brake on seems better.Tried it with the brake off and could get a slow crawl along the 3 feet I have to spare.
I'll be trying it on the road again tomorrow ,but I think I might have an idea of how the clutch is supposed to work..John
 

Chris Launders

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Never thought about the thicker friction plate, I thought I had been imagining it was lighter when I first got it, it did have a one piece friction plate with 5 ears but it was in 3 pieces !! I tried a norton multiplate conversion but have gone back to the standard clutch (now I've kept the oil out), I have indeed fitted a bonded plate but may have a one piece one somewhere or I can space the C27 out a little.
Chris.
 

greg brillus

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Just some other points of interest....the C15 spacer tubes need to be pretty much exactly the same length, otherwise the clutch plate will not lift squarely. The length of the C14 pins does not matter so long as they don't protrude past the end of the C15 tubes. If you fit new C 29 Springs check they are not binding in the C30 spring cups, as this will also stop the outer plate lifting squarely. It is most unfortunate that the outer springs are not able to be adjusted individually, as per a conventional muti plate. Rather than endlessly changing the outer springs around to get a wobble free lift, try and space them as equally as you can with regards to their length, as In the two longest ones opposite each other and so on. With the bike on rear stand, in top gear and clutch disengaged with handlebar lever, rotate rear wheel, and with a texter pen, mark the outer plate where its high point is, and place thin 3/8 ID shim washers between the spring/s and the C27 outer ring. This means the shim will sit over the C15 sleeves, and effectively puts extra load on that spring. It can be tricky but make sure the shim does not jam under the C27 ring plate when the 2ba countersunk screws are tightened. It seems painful, but trust me....it is far easier than endlessly swapping springs to achieve the same result. Generally I have found the nominal length of the C15 tubes to be around 0.945 and 0.950 in length. If the springs are tight in their cups, just linnish them on the outside until they are a free fit......if they bind, you will not be able to get the outer plate lifting evenly. The original Vincent clutch is a complex item and like other features on these machines....is unique to them alone, with regards to a multi plate clutch, I think the original clutch is best, as the lift mechanism was only designed to lift one plate...A multi plate clutch can be made to work ok, but I found only when run dry, and without any wobble from the chainwheel bushes, and so on. That is that a mutiplate needs to run quite true, or else the plates will not free easily. The twin gearbox is almost indestructible, and most blame slow gearchanges and poor shifting on the gearbox. This is in most parts completely wrong, and is almost always due to a poorly set up clutch. Some people I know who actually know Vincents quite well, still believe the clutch is centrifugal.......Go figure....Hope this is of help............Greg.
 

Bill Thomas

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On my Special, The Mainshaft is bent, 10 years of Sprinting ? So that one will never be right !! Cheers Bill. P.S. Dave hills told me to not use 3 of the springs, But on my bike the clutch slipped, Maybe a bike with less power and well set up shoes might get away with it. Cheers Bill.
 

BigEd

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I think I read somewhere (so it may not be correct) that the clutch was originally designed to use just three springs. This proved to be so light that there wasn't enough feel to it. If this was the case a stiff or poorly routed cable would have also hindered the handle bar lever moving back to the released position.
Greg has mentioned above many good things to check.
A few other things to look:
Check the travel of the lever inside the gear cover. Make sure that the cable is adjusted so that the G91 lever doesn't quite reach the G50 plate when you pull the handlebar lever to the bar. You will then get the maximum lift available.
When you have the primary clutch plates off put finger pressure on the end of the pushrod while operating the handlebar lever. It should move in and out smoothly and very easily.
Try just three springs and that will soon tell you if the heaviness is related to too much spring pressure. The primary clutch is supposed to be able to transmit a certain amount of power on its own. ( I once rode back 100 + miles from a trip to Wales on the primary clutch when a failed oil seal let oil onto the brake shoes. Gentle use of the throttle allowed 50 mph speeds.)
 

nkt267

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The clutch is still not good..
I have found that I can rock the clutch drum a little,it looks like the chainwheel bushes need replacing or is a small amount of play OK??.John
 

BigEd

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The clutch is still not good..
I have found that I can rock the clutch drum a little,it looks like the chainwheel bushes need replacing or is a small amount of play OK??.John
A bit of play should not cause a problem. A small clearance at the bearing is magnified at the sprocket teeth.
 
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