C: Clutch Clutch sprocket play

milohiscox

milohiscox

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Hi
I have been spending some time rebuilding my Rapide clutch and am pretty happy. Just got a quick question on tolerance:

I've replaced the clutch sprocket PD20, its two bushes PD22 & PD24, and also the shoe carrier C3. Now that it's assembled, the sprocket and drum assembly has 40 thou of end float on the carrier spigot which feels excessive. Any advice whether it is? When the clutch is engaged, this amount of play might help the primary chain run true, but at the cost of clutch pushrod travel?

(Hopefully video posts ok)
Thanks
Milo
 

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greg brillus

greg brillus

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40 thou is too much end float......simply use a clutch C 19 shim washer under the flange of the C3 carrier to reduce this play down to around 5 to 10 thou.......Sometimes (mostly) you need to chamfer the inner edge of this shim so it sits better against the small fillet in the corner, once you slide a shim on there you will see what I mean........Cheers and good luck with it.
 
greg brillus

greg brillus

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I forgot to mention the importance of setting up the generator sprocket at this time as well......as it needs to ideally run central to the middle set of rollers on the chain.......so 40 thou end float could cause the teeth to rub on the inner plates........Thanks for the comments on the racer.......I've not said too much on account of us not knowing how it will go after so many mods.......final testing and fuel set up this week.......all looking very good at this point and it performs very well........pulls clean to 7000 easily and just keeps going.......only my set limit on RPM is the hold back due to the long stroke crank........a short stroke version would be amazing.......that is next on the list........Cheers.....G.
 
milohiscox

milohiscox

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For anyone interested I turned a thou oversize aluminium mandrel and tapped the carrier on square and machined it down. Ended up with 7 thou end float which feels much better. Resisted turning a recess in C3 for an additional o-ring as suggested elsewhere, will follow years of Vincent tradition and gum up the splines, anyway I have new G3 and C3 and the spline fit is fantastic.

My sprocket bush PD24 has the scroll in the direction that encourages oil into it. Clutch Thy Beast discusses this at length and suggests soldering it up to ease the work of seal PD25. I didn't find much discussion on this in the forum, so have left it as is, particularly as I have machined a tight 0.001" running clearance on the spigot. Any thoughts on this appreciated.

I also note that the majority of the clutch literature (Whitakerpedia, KTB, Instructions sheets etc) focus on the mechanical set-up of the clutch, springs, play, particularly oil retention. However my own experience of this rebuild was that 80% of the time was spent gently sanding the relined shoes until they all made good, simultaneous contact with the drum (in some cases taking up to 0.015" off). This was much easier with the plungers removed and all other bushes and tolerances remedied, demonstrated in the attached video with a 0.001" feeler gauge.
 

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Simon Dinsdale

Simon Dinsdale

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milohiscox said:
My sprocket bush PD24 has the scroll in the direction that encourages oil into it. Clutch Thy Beast discusses this at length and suggests soldering it up to ease the work of seal PD25. I didn't find much discussion on this in the forum, so have left it as is, particularly as I have machined a tight 0.001" running clearance on the spigot. Any thoughts on this appreciated.
Click to expand...
Vincent factory instruction sheets says minimum of 2 thou running clearance on bush PD24. If you PD24 is made of phosphor bronze which is what the factory instructions sheets describe it as, then I suspect 1 thou clearance could result in the bush potentially picking up or even worst seizing on the spigot.
 
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