The Knowledge - Velocette Owners Club

E. The Drive Train
E.1. Primary Drive, Chainwheel and Clutch -
L #151 The large clutch ballrace assembly C26AS is an interference fit in the chainwheel
assembly, although the same problem would also exist for the clutch thrust bearing if there was no oil in
the chaincase, as you point out. I have converted my clutch thrust bearing assembly to rollers also. I
would be interested if anyone else sees this as a problem and also if anyone knows of a cheap source
of the large ballrace assembly. The last one I purchased was about £90 so I would not want to replace
it too often.
#154 I got mine from Grove Classic Motorcycles in Bedfordshire U.K. (+44 (0)1582 873066) as mine
was cracked and loose in the chainwheel. I checked the price list and they are currently listed at £95
#156 Re: clutch chainwheel bearing (not throwout bearing) life with a belt drive. There will always be
some oil in the primary from the engine breathing through the main bearing. I think we should ask
someone who's put some miles on this system, though, to find out if it's enough. Those bearings
sometimes are in short supply! And as a sidebar, on the throwout bearing, rollers are the only way to
go. Two sets of the ball type wore out in 3 years on my VMT before I got wise, and have never had to
change them since (this is 12 years ago).
#157 Some new chain wheel bearings are a thou or so undersize (not necessarily those from Grove
Classics), and have a habit of dropping out of the chain wheel. Check the OD of the new bearing
against the old before you fit it.
L #160 My Venom has traveled just about as far in 13 years with the original ballrace release
bearing. It is adequate when properly lubricated. I was slipping the clutch like a mad 125 GP rider on
the way up Pikes Peak last summer! Stinking SUVs... Simple geometry says that the roller setup needs
good lubrication too. If the heavily loaded rollers on a crankshaft skidded like they do in the release
bearing they would not last a minute. I agree that someone with experience with running a "dry" primary
should give us some hard facts about bearing life. Race bikes probably don't see the long-term clutch
abuse that a street Velo does. Perhaps
#161 Reference the clutch release bearing saga, I modified the brass cage on the bearing by filing it to
take 3/16th" rollers after reading about the mod in Fishtail in the 70's and never had to change any of
the parts despite using the bike as everyday transport for years
#162 When I had mt first Thruxton back in the late 60's early 70's it seemed to "eat" thrust race
bearings of the ball type. I now use the roller type and find in the 10 years of ownership of my second
Thruxton I am still using the same bearing
#164 I have been using bonded clutches and better quality steel plates for about 3 years now and find
them a great improvement. I find that neutral is easier to select, the gear change is smoother, also
when abused the clutch will go out of adjustment but return to its original settings when "rested". I
have found that the chainwheels made in Germany do not last long and seem to wear very quickly. I
have just had them relined at Safetex in Yorkshire, but to date have not had the time or the weather to
used them, has any one else used Safetex relined chainwheels or plates?
L #423 I have a 1954 MAC and I want to rejuvenate the clutch. I have a few bags of inserts from
Martyn Bratby, enough to do all of the plates and the chain wheel. Is it as easy as popping the old ones
out and bunging the new ones in? Or are there other things I should do as well?
#424 Plates must be reasonably flat. Tabs to be deburred, insert new inserts, put every 2nd one in then
reverse plate, and finish off. I have found that a dab of araldite holds the inserts in place , they tend to
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