Hi all, I have just brought a used Sigma slipper clutch and fitted it as explained in Superdans thread [/url] viewtopic.php?f=18&t=11308&p=128816&hilit=sigma+clutch#p128816[url].

I went out for a quick test ride and the slipper function seems to be working fine but some of the juddering through the brake lever when changing gear, up or down, doesn't feel right at all! I had a sigma style clutch in my old R1 and was used to some slight plusing in the lever when the down shifting but nothing like this. I'm assuming that something isn't quite right.

For starters, the clutch pack measurement difference between the clutch being empty of plates, and then full, is 1.73mm. It should be 1mm apparently. I have strangely gained pack height with a 7000 mile old clutch. To get it correct I would need to order two GSXR steel plates that are actually THINNER than the standard ones (stock was 2.25mm by my measurements.)

The other thing is, my included instructions from Sigma say that the clutch pack should fit in exactly the same way that it is in the standard clutch. This means that the two judder rings and large O/D friction plate go first in the pack. I understand how this could be problematic as particularly the thinner judder ring could drop into the recess of the inner hub when it lifts on its ramps, but surely if this could happen Sigma would advise against it wouldn't they? It seems my instructions must be different to Superdans as his don't seem to say this.

Any advice would be appreciated.

I presume you mean the clutch lever?

It was not the best feeling through the clutch lever changing gear when I did mine, it was notchy compared to the smooth action before but I got used to it, you pulled the clutch to the biting point and it felt very agricultural / instant / notchy like you describe.

I rember playing around with the two judder rings and remember one being conical and you had to get it facing the right way.

If I can help I will, BASH69 is the man though on this subject.

I believe DP has the Sigma too, I believe he is saying he gets that too.

Double check what you have done and that its in the right order if its still the same, it correctly fitted and what DP and I also feel/felt, a notchy feeling.

I defo remember getting a judder through the lever when changing to first, lets rembenber its a race modification not a street one, not sure if the others slippers are the same or not for the SD.

You could always call Neil Spalding fromt the sigma website (he does the tech commentary on Eurosport) he was a condasending tw@t with me though.

Dan is right, that click you feel through the lever is quite normal.

I have had all the symptoms you describe, though perhaps not a severe as you suggest, throughout 34k plus miles without any problems - if in doubt, contact Neil who, unlike Superdan, I've always found helpful - you're welcome to try mine for comparison if you're ever in the London/Kent area.

Ok guys, thanks for your advice. Maybe the judder through the lever is normal and just a lot more pronounced than i'm used to compared my last slipper in my R1.

However, I have pulled it apart again and carefully measured the clutch pack/pressure plate clearance to see if this is wrong & maybe making the clutch lever judder worse than it needs to be. The clearance measurement is too much at 1.8mm when its meant to be at 1mm. I find this really strange as I was expecting to have to put in a thicker GSXR steel plate to compensate for the wear in the plates. By the looks of it I will have to get three 2mm GXSR plates that are .25 thinner than OEM to get the clearance nearer to the desired 1mm. Weird.........

Anyone have any idea what effect a thicker clutch pack would have compared to a thinner one?

Lastly, the OEM steel plates are meant to be between 1.95mm-2.05mm thick, mine are 2.25mm. Yet my combined clutch pack is 51mm, bang within spec. I don't get it...