Problems with a slipping clutch

I went to collect my G3LS bike from the mechanics yesterday following various work replacing the valves, guides and springs as I mentioned in my previous post here. On the test ride I was having some problems with the carb which caused the engine to cut out a few times, but then the problem got much worse when the clutch started slipping when I was trying to kick-start it back to life.

Eventually I gave up with the kick-start and (in the sweltering Hong Kong heat) managed to haul the bike to a suitable slope and bump start it on the way back to which allowed me to ride back to the mechanics.

And so off came the primary chaincase for the first time since being back in India to see what might be the matter. Looking at the clutch it was fairly obvious that the plates were quite worn as they only filled about 2/3rds of the basket. The clutch had always jangled like a bunch of keys when it was disengaged, but I think the extra compression from the new valves must have been just too much for it causing it to slip.

When the plates were removed for cleaning and degreasing it also became very obvious that the basket itself was quite worn. The metal tabs welded inside the internal rim of the basket were rather rounded off, as with the tabs around the outside of the friction plates. So that accounted for all the jangling when the clutch lever was pulled in!

However with no spares easily to hand, it would have to be a case of taking some photos for later reference, putting it all back together and adjusting up the clutch springs to hopefully give enough bite to make the bike ridable again. The cleaning and adjusting seemed to do the trick for the time being at least and allowed me to kick-start the bike and ride it safely back home.

Longer term, it would definitely need some new friction plates (the metal plates didn’t look too bad) and a new clutch basket to fit them in. Like nearly everything else on this bike, nothing was straightforward though. The friction plates were easily available so no problem, but I couldn’t locate a new or good used basket from any of my usual sources, and so I’d need to find an alternative.

It turns out that 1951 was a bit of a strange year for clutches on these Matchless G3’s. Up until 1951 they used a ‘CP’ type gearbox and clutch which was then changed to the Burman ‘B52’ gearbox and clutch the following year (hence the ‘B52’ name). However, the 1951 models apparently used an intermediate combination of the old CP gearbox but with the new B52 clutch fitted. Thanks go to Steve at AMC Classic Spares for pointing that out to me otherwise I would have assumed that my bike had the CP type clutch!

I got the replacement clutch plates on order and set about working out how I could either replace or recondition my existing outer basket. A few more of the the reference photos of my B52 clutch are shown in the gallery below, although I didn’t get chance to take one with it all back together to show just how worn the friction plates actually were. It goes to show just how robust these old bikes actually are as I suspect a modern gearbox wouldn’t have worked with a similar amount of wear and tear!

Update December 2011: In the end I was able to get my old clutch basket reconditioned and new tabs welded inside. There’s more info and photos of the reconditioned clutch basket in this post.