Clutching at straws
Oliver Tabram is having a bit of a nightmare with his 1972 Triumph Daytona. He’s replaced the entire clutch, the pushrod and the lift mechanism – but whenever he pulls in the lever, the clutch is stuck. If he frees it on the kickstart before starting, when he puts the bike in gear it’s stuck again and grinds. He says: ‘The engine breathes into the clutch housing , so the handbook says you should use engine oil in there. I’ve tried 20W/50 and 10W/30, but the problem only goes if I run the clutch dry. That’s no good, so what do I do next?’
What indeed... I’ve known this happen when the clutch shock-absorber rubbers degrade, forming sticky black gum on the plates, but Oliver’s are new. Since the problem doesn’t occur without oil, presumably either the oil is causing the problem or it’s turning some already existing issue into a problem.
The oils Oliver’s using sound harmless enough, although I think Triumph recommended automatic transmission fluid (ATF) for the later 750s using this breather system. As it’s much thinner than engine oil, it might be worth trying.
The problem is so unusual that I wonder about the plates themselves – are there some dodgy ones around that react badly to oil? I have also known clutch plates drag badly if they are not oiled upon fitting – it’s not quite the same problem, but what if they’re soaking up the oil, creating a sort of vacuum bond with the steel plate? Sounds a bit improbable, though. Also, Oliver should check that the clutch is lifting squarely.
It’s always possible that this problem will go away with time. I’d say try ATF in the primary and get some miles on the bike. To avoid crunching into gear, try pulling the lever and snapping the throttle open a few times – the jolt will hopefully separate the plates. I hope Oliver will let us know what he discovers...