Slipping clutch opinions?

OK, so I fit the RC8 stacks and go out for a 100 mile blast on Sunday. Roads still a bit slippery from the crap rain and cold the last week but it's sunny and roads are mostly dry but it's bitterly cold. Get onto some fast roads and start to see what the difference is, if any that I can feel. To be honest it's hard to tell - maybe this is something only a dyno run can show.

But whatever, the difference I think will be only seen at higher rpm anyway, from what I know about the way these stacks work and when the effects of airflow and resonance actually get to effect a difference to the engine breathing. So on the way back I go onto the M23 and it's clear of cars mostly so I start to try a few high speed runs. Is it faster to hit high speeds? I don't know but I'm experimenting with 5th gear roll-ons and 6th gear roll-ons and such like.

At about 125 -130 mph I'm suddenly getting the horrible feeling of clutch slip. It's subtle.... but definitely there, I can feel it... that horrible raising in revs, (confirmed with the rev counter), but no associated speed increase. I try a lot of different permutations with speed, gear and brutal use of throttle increase and it's definitely there. I try low speeds and low gears and cannot make it happen. It's just at high speeds.

So basically I have a situation where at 120+ mph in 5th gear when I then give it full throttle I get clutch slip. If I change up to 6th gear it will just accelerate until, presumably, terminal speed, (which I never got to because of road conditions and traffic and worry about police), but in 5th @ about 8,000 rpm it seems to make too much power and slips like mad.

So my question is.....

Do I have a problem with the clutch or a problem with too much power for the clutch at these revs/speed? Is my clutch worn out or I have fooking amazing power increases?

PS It's important to know - I have a Suter slipper clutch fitted which has been brilliant and fine for nearly three years. Running the original SD plates from new in 2007. Maybe the plates are just worn out? Bike's done 10,000 miles now.

I'm no expert bic but my dealer did say that slipper clutch plates wear faster than on a standard clutch. Maybe a change of fluid would help too? I would imagine if it is on its way out that out would slip more in lower gears though.

Good luck with it.

Ive heard the same with the plate's wearing out faster also,,,three years is pretty good IMO,,,,time for a re-pack,,

Bic, again no expert, but I'm approaching 45k road miles plus race miles on my original Sigma - no sign of clutch slip yet and 10k miles on an OE (?) set of plates, either in a slipper or OE clutch, does not seem a lot - one thought, though, the Sigma uses GXSR 1000 clutch springs, what does the Suter use?

The first thing I'd look at is the original diaphragm spring plate on the Suter. Yes, the friction plates will generally wear faster with a slipper clutch on any bike.

I'm guessing you ride your SD pretty hard, occasional trackdays, etc. Thrown in say, another 10% horsepower. All this accelerates wear. Pretty easy to smoke the friction plates clutch in 10K miles (or less) on a big torquey v-twin ridden hard.

As I assume you know, doesn't take a lot of time to pull the plates and put some calipers on them.

had mine out at the weekend too bic and thought I detected a bit of slip, but it was hard to tell whether it was hesitating or slipping what is the preferd oil? the only thing different from last year for mine was a rise in bhp, that along with a change to fully synthetic oil caused a previous bike to burn out plates

Thanks for the comments guys. Going to get the plates out next opportunity and check the tolerances. Like is mentioned above the Suter clutch doesn't use conventional springs but has a spring steel plate instead so I don't think the issue is there. The bike had an oil change not that long ago at a new place, (for me), and I don't actually know what they used but I will check.

Maybe you're right. I was a bit shocked when I first saw the Suter "spiring" as it just didn't seem to be the kind of thing that could exert the same kind of pressure that six or more coil springs could do. But I had faith! Can't remember - it was so long ago, but I'm pretty sure that the kit I had came with some other options for something - you had to choose which bits to fit. I need to go look in the box. Maybe.....did it come with three different options for spring strength in the kit? I remember it had to do with the amount of slip you wanted and I opted for the middle one - whetever it was.

Are you guys with the Suter getting alot of clutch chatter at idle when in neutral ?

I just received my STM. Sat on my desk at the moment but it seems to be a quality piece of kit and overall seemed to have the best reviews for fit and use.