CL003 CLUTCH
Following a recent gearbox re-build I took my Viper out for it's first run of
the year. I covered about sixty miles, not overdoing it and keeping to about
fifty MPH on the main roads. I stopped the engine three or four times and
restarted without any problem.
Unfortunately after the fifth stop at a friends, the bike refued to start. After
the normal plug change, I stook the cover off the mag to check the points and
found that they had closed to about 12 thou. I re-set them to 16thou and tried
again. I then discoved , by watching the mag as it went round that I was not
getting a good kick through. I assumed that the clutch was dragging and
re-adjusted it.
Whilst doing so I saw that the clutch springs were all leaning over. Without
stripping the clutch there was little I could do, so I attempted to start the
bike. No problem, one good kick and away she went.
I made my way home, twenty miles, and as I did so I felt that the gear change
was getting stiff. I made it home but on arrival found that the clutch was
dragging again and the gear change was very stiff.
Two questions please,
1. How do I stop the clutch springs from pulling out of position as I adjust the
clutch. We had noticed this phenomena as a friend re-assembled the clutch
following the gearbox rebuild. The springs seemed to be gripped by the outer
clutch rimg with the result that the springs were all pulled to one side. With
the sprocket off this was easily rectified, as small screwdriver levers them
back easily..
2. Less seriously.... Will I ever be able to take the bike out , enjoy the ride
and return without any problems :-) - Grant Kinnaird 13/1/2001
A familiar situation...!
The Velocette clutch is great when perfectly setup, but that has to be done with
precision. And when any one of several things are wrong, it can slip or drag, or
do both at the same time.
First, to answer your specific question:
I assume the only time your springs have cockled is when tightening the sleeve
gear nut, not when just adjusting it? I've never known it happening once the
sleeve gear nut is tight, unless something has gone wrong with the assembly of
the clutch, or wrong parts used; etc.
Everyone suffers from the springs 'cockling' as you tighten the sleeve gear nut.
This is often attributed to the tangs on the springs being rough/sharp, and/or
the shims under the nut being burred. I once fitted new everything and smoothed
the springs on an oilstone and oiled everything - just to see if they wouldn't
tilt. But they did. The other 'well-known' factor is the spring holder not
turning smoothly - or often not at all. This alloy ring gets stuck and stops the
springs rotating with the sleeve gear nut, which is to be preferred because if
only they would move with it they wouldn't cockle. So I had also taken every
burr off the spring holder and made sure it span easily inside its housing. But
once assembled and tightening, it still didn't rotate, so the springs cockled
over.
But in fact the spring holder cage is the answer - remove it (probably with
difficulty if very old) from its housing in the spring holder assembly. Remove
burrs etc so it could rotate if it ever wanted to, but then put it back into its
housing ONLY HALF-WAY. So it then holds the springs at their middle, leaving a
shorter length sticking out at the front and back of it. This length is too
short to cockle.
Another solution is to use a tool like the one I have which slips two half shims
behind the sleeve gear nut, between it and the first shim. These half-shims have
a long extension that can be wedged to stop it turning. Thus the springs and
their holder do not turn as you tighten the sleeve gear nut. Before fully
tightening, but after the cockling point, remove the half-moon shims, then fully
tighten.
Supposedly, once cockled the springs will never be right, but we have all pushed
them upright (repeatedly, and tediously...) with a small screwdriver and by
itself this hasn't spoilt the clutch.
Even the slightest degree of slip in the clutch will reduce the speed of
rotation so a Venom with magneto won't start.
The most usual cause (assuming the friction plates have at least some meat left
in them, and of course that the clutch has been adjusted exactly according to
the drill, leaving a little slack in the release thrust race assembly and a
little more in the cable; and the chaincase isn't overfull) is warping plain
plates. These may be warped when cold, or warp when hot. It only takes a small
amount of warping to cause dragging and slipping. Supposedly you need to rub
them down on a flat surface when cold. Hot warping requires a lot of heat, and I
doubt that is your problem - it's probably that you have more compression to
overcome when hot, resulting in slip from the borderline clutch.
Since you found the gearchange getting stiff as well as the clutch slipping on
kick-starting, it does sound as though your plain plates are warped. Nowadays,
new high-tech ultra-flat ones are available to club members from the Spares
Scheme, and since it only costs £15 + p&p for all three that's the first
step to take.
Yes, any Velo can be made to run most reliably and satisfactorily except for the
inevitable 'fatigue failures' after 40 years use. But see the EV005 saga for a
feel for the sort of steady sorting-out sometimes necessary on an acquired bike.
- TW 14/1/2001
I'll certainly get the new plates. I'll also try the spring holder cage
modification.
The last time the clutch was re-built I refaced the shims on a diamond stone,
thinking that the shims were somehow gripping the spring ends. We re-assembled
the clutch but the springs still cockled so we straightened them with a screw
driver. It was after adjusting the clutch the other night that I noticed that
the springs were all leaning over again, so I assumed that it had happened when
adjusting the clutch. - GK 15/1/2001
It does sound as though your springs cockled just by adjusting the clutch. If
so, I think this may indicate that there is something else wrong.
When the sleeve gear nut is fully tightened, the springs should be almost
coil-bound, and the gap between the shims and the outer lip of the spring holder
assembly should be pretty small - less than will allow a screw-driver in. (Which
you shouldn't need to do by then, because the springs should have stopped
cockling.)
You may have a non-standard length distance piece, or short thrust pins, or
other things. But usually these show up as a soft clutch which won't let you
kickstart at all.
Things to check are that the clutch chainwheel is pretty exactly in line with
the engine sprocket; and is the gap mentioned above around 50 thou (from memory)
or quite different? - TW 15/1/2001