Clutch Slip

Hi Chaps - I have rebuilt my 850Mk2A as a 920 - the bike runs beautifully but now that it is nearly run-in I've found that the motor seems to be 'overwhelming' the clutch. I've have fitted just about every conceivable modification to the clutch in the past (sintered plates, high-pressure plate, belt-drive running dry etc.) and as a 850 all was perfect but now I find that when I open her up at circa 70 mph the clutch seems to slip. As there doesn't appear to be any more room for extra plates the only thing I can think of is a stronger diaphram spring however I've never seen such an item listed anywhere - note that clutch action is very light thus I could afford to fit a stronger spring if necessary/available.

Any ideas please ?

Cheers,

Mark Woodward

I fixed my clutch problem with a Dave Comau clutch push rod seal. its a nut with recess for an o ring that prevets oil from the gearbox coming down the rod and getting on the plates.
My clutch would drag when idling and slip when accelerating both due to oil. After cleaning the plates and screwing on the seal no more problems.
There are other fixes on this forum that others could suggest.

Hi dgwilson - I forgot to say that I've already fitted an oil-seal modification to stop oil from the gearbox reaching the clutch - it works well and the clutch is bone-dry of oil. Thnks for the suggestion though.

Cheers,

Hi Mwoo
You mention a you have sintered plates in your clutch, and are running dry with a belt drive.
I would have thought you should be running with fibre 'sureflex' plates if you are running dry.
I would also make sure your basket is full. i.e. if you put all the plates, plus the thicker STEEL (don't get an alloy one) pressure plate that you need if you run sureflex fibre plates, you should be able to just get the snap ring in the groove.
Could I also suggest you contact Steve Maney for advice. He puts big Nortons together for racing with 90 bhp, so he should be able to advice. Mick Hemmings also...

Steve Maney contact details....
Telephone/Facsimile: 01924 265158
(+44 1924 265158 outside UK)
stevemaney@talktalk.net

Stu.

Hi Ludwig - ref the gearbox - no I don't have an outrigger bearing but I have rebuilt the box in a 'toughened-up' case with more 'meat' around the bearings - it all seems OK at present. Thanks to all ref the sintered plates - looks like more expense changing them !!!

Cheers,

Remember Mark, If you change to sureflex I think you will need a thicker outer pressure plate to obtain the correct clutch stack height. Don't buy an alloy one, they wear the outer plate badly. Get a steel one.
Stu.

Mark, at a guess, is your stack height too high....you say you have a very light clutch, have you got the right number of plates and the "thin" pressure plate or a thicker one which is meant for fibre plates??