New Belt Drive

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kraakevik said:
Commando clutches almost always wobble under light loading but straighten up when revs and torque come into play. After nearly half-a-million miles on my '72 Combat I now shim the primary to let the clutch center seat solidly on to the splines without any circlip. Primary triplex chain drives on Commandos are as bulletproof as any load-bearing mechanism from that era if the crank, gearbox mainshaft, bearings, lubricant and adjustment are in gee--I'm on my second chain, third mainshaft bearing, third clutch center and third mainshaft--and probably my fifteenth or twentieth clutch pack.

When I got my first pair of 114 body DOHC Mercedes in the '70's Helmut the mechanic wearily answered my constant queries about this and that with, "Just drive it." I've found that to be excellent counsel.


Tim Kraakevik
kraakevik@voyager.net
Three Commandos
Click to expand...

What do you use for shims?
 
I actually have a collection of E-Bay engine sprockets that snug up on the crankshaft with slightly different clearances--haven't had anything kiss the inner case yet. That triplex setup will tolerate slight misalignment for decades--it's probably the most robust subsystem on any British motorcycle. As I used to remind our mechanical engineeers when we were building Byron, Braidwood and LaSalle:

When in doubt
Make it stout
Out of things
You know about



Tim Kraakevik
kraakevik@voyager.net
Three Commandos
 
Nortonspeed, I was just lurking on the learning curves
similar to mine, then you mentioned the Quafe main shaft. Huh.
Where does one acquire that stiff main shaft wonder please?
Factory like to cork screw bend.

Until I got 2 early Cdo clutches to run true I didn't believe
it possible. Most effect in my case were the sleeve bushes
wear, but all components as listed must be nearly as new right.
My, Deer adapted drive belt finally stayed on w/o the
front plate on pulley, after a mangled primary mess before
going though the whole drive train recipe.
Don't know out how long the steady as she goes clutch lasts though.

Disconcerting to see amount of belt deflection, but don't
want to get tighter than can just work on/off w/o G/B
adjustment or 90' twist in mid run. Belt length don't
change like chain but the pulley distance expansion can
sure tension a cold slightly over tight belt to musical tight : (

There are or should be charts from belt suppliers
that show the optimal "tension" going by the size
of the pulleys and the belt tooth count, then >>>
By giving the distance to set the pulley centers to,
not going by any tension sensing method, just
pure geometry. I've a hard copy but don't know
about references on web.

Intend to set belt this way on my growing special - Maney 40 mm
drive - but once set the G/B will be fixed in place and
I'll check how much twist in a run or sag by a tug
to see which side of optimal my past crude way was.

hobot
 
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