Plate expectations
Still suffering clutch slip on his 3T Triumph after replacing the friction plates, Ed Hamley confessed he’d been ‘too tight’ to replace the steel plates and some were a bit rough. Tut, tut Eddy! Clutches work hard and are not the place to economise! He asks: How thick should the clutch friction material be? Could the dodgy steel plates be the problem? And is it possible to run the primary dry, using chain lube on the chain.
I don’t think the thickness of the material matters too much, but it must be smooth and flat – rub them on sandpaper on a flat surface. A thinner clutch pack will reduce spring pressure, though, so you may need to tighten the springs more. Plain plates must be in good condition. On my first Triumph I kept replacing friction plates – but the clutch still slipped, despite winding the springs in so hard I developed a brickie’s handshake. I finally realised the steel plates were warped from heat generated by slipping. If you can afford it, it’s worth replacing both friction and plain – if not, at least stack them all together and look for gaps.
Yes, you can run the primary on chain lube, but with a short chain on small sprockets it will need doing every ride. But primary case oil does more than oil the chain – it cools it as well as lubing the crank shock-absorber and the clutch release bearing.
The 3T is relatively low powered and I think treating it to a new set of plain and friction plates and a set of springs would sort it out indefinitely. When I built my 1968 Trophy, I had to renew the complete clutch and it’s worked perfectly ever since, apart from needing one new cable. Not bad for 34 years’ use...