F1 Sport clutch judder

[fogrider]

Hello all, I'm hoping to put the Sport back on the road for 2015. I've never been able to cure it's bad clutch judder, hence off the road. It's a diaphragm spring which looks OK, I have swapped the plates, no difference. Can anyone offer any thing I could check ?, or, who would be the best to take it to with good experience of this type of clutch?Regards, Terry, East Yorks.

[johnbirchjar]

If you live in East Yorkshire I would think Graham Wilshaw in Leeds has got to be your nearest expert,J.B.

[fogrider]

Thanks JB, I bought the bike off Graham, it was he who lent me the clutch plates to see if that was the problem. I took them back and said there was no change, he could'nt offer any other advice. I might take it all to bits again and have a really thorough check of all the parts. It might be worth a ride to Shenstone with the bits?Too many bikes, too little time........Regards, Terry.

[fogrider]

Shenstone?, I meant Andover, too far though. I've been told in the past that the clutch is the same diaphragm as a Commando, don't know if that's true. Anyone?

[Interpol2471]

I guess you have changed the cush drive rubbers and checked all of the plates were perfectly flat?That would be my first call after that you may need to check the basket for scoring but that would be after high mileages and from the sounds of it you have not used it every day!You can check for run out on the diaphragm plate by holding in a lathe and centre using a dial gauge.Andover does not have a resident Rotary expert on site but you can request telephone help from one of the staff at another location.

[fogrider]

Yes, I renewed the cush rubbers and, out of the big pile of plates Graham lent me, I selected ones that were true on a surface plate. Checking the diaphragm spring for run out I did'nt do, will try that in the new year when I have it to bits again. It is a fairly low mileage bike , owned from new by Terry Hobbs, I believe he had a dealership on the south coast somewhere. Roll on summer.Thanks, Terry.

[gripper]

Can you describe the symptoms you are getting more precisely. The F1 is prone to a lot of transmission snatch at low speed and on a feathered throttle. This problem disappears as the pressure on the drive system is increased , i.e. with an opening throttle. Have you ridden the bike when the clutch did not judder? As you let the clutch out is there a judder as the lever is going out, or is it there all the time at low power settings? (with the clutch out)

[fogrider]

Hi, its' always judder'd, right from collecting it from Leeds. Its' only as the clutch lever is fed out to take up drive. There is no transmission snatch and drives OK at low speeds/high speeds. Clutch plate(s) seemed the obvious problem, but no difference when I tried the other plates. Checking the diaphragm for run-out is something I haven't done and it has also been suggested the large circlip could be twisted or buckled enough to run the diaphragm out. In the past, two well known names said it was probably the centre nut that needs truing up. I can't fault the nut but might check it again next time out. I can't remember what the clutch drum runs on, a plain bush or a ball bearing?I suppose that would allow the drum to run "off" too.Great bike otherwise !Cheers, Terry

[wust588]

I can't add much to what has already been suggested, but it is worth spending time making absolutely sure the plates are flat ie on glass. A few thou' can cause trouble.When you refit the spring (in it's compressed state), make sure it spins concentrically within the clutch drum after refitting the spacer and circlip, before releasing the tension.Try ATF as the lube.The carb tickover balance can cause judder if not even.Does it judder cold and hot? What's the ball bearing at the back of the clutch like?ATB.

[fogrider]

The judder occurs both hot and cold , when I get round to stripping it all out again, I will make a better assessment of the diaphragm,the circlip and that back bearing. I,m thinking of making up a carrier so I can mount the assembled clutch in the lathe, maybe borrow a clutch shaft, might show something moving off true. I suspect I will be buying a new diaphragm, we'll see ( not sure when, this is another job to add to all the other jobs I said I will do this spring !). Oh well......

[site admin]

I was told that Norton used to bead blast the plates to pacify customers who complained of the take up. But the fix only lasted 500 miles or so: Only one employees comments, never had chance to confirm. Ducati are worse, they simply say; Worth reducing the load on the diaphragm by replacing the original 0.8mm spacer ring with a 1mm thick section cut from a clutch retainer circlip.If you still have problems, it's got to be a bent plate, you will need to go through each of the 9 brass and 9 steel plates in the hope of finding a rogue one.An 18 plate clutch with minimal clearance is always going to be a difficult fix!Graham

[fogrider]

Many thanks for all the interest and advice, I will be having a fresh look in late spring ( bogged down with a classic bike re-build and classic car jobs for now).Cheers, Terry.

[fogrider]

Job done, it was the clutch cush rubbers after all !. I had bought them 11 years ago and assumed I had fitted them. I had'nt. Mot'd and taxed yesterday, then an afternoon blast up the B1247. Fantastic fun. I was 57 when I took her off the road, 11 years later the riding position now feels decidedly race-like. The 12 year old tyres did'nt feel very racy at all but I had'nt replaced them in case there were still problems. Tyres to be replaced now for the summer .Pilot road 3's seem to be quite cheap. Any recommendations ?Rotaring again, Terry.