Tech Question: Types of clutches

[Z_Fanatic]

What's a difference between dry, wet, and slipper clutch? How do they work exactly? Are the current Japanese sportbikes fitted with wet clutch?

[speediva]

Most Japanese sportbikes have had wet clutches. I don't know exactly what they are, but I do know they have been traditionally wet clutches. Now, the clutch in my car and the clutches on Ducatis are dry. Again, I don't have the "know how" to explain more than that, but I figured I would throw in my $.02 since I can.

[Z_Fanatic]

thanks.

I figured most Japanese bikes had wet, since ninja 250, f4i got one. I knew Ducs have dry clutches, plus you always said they sounded and worked like fart

After reading that article, I found Kawi ZX-6RR and now ZX-6R use slipper, that's what aroused my curiousity.

Btw, my guess is the purpose of the slipper clutch is to regulate the amount of power sent to the rear wheels to prevent tire spin. Like an adjustable traction control. The Slipper also helps prevent damage to gears and driveshafts by reducing the shock loads transmitted to the drivetrain in situations with the throttle held wide open. Allows the rider to quickly decrease gears without risk of locking the rear wheel, and/or over revving the engine, with evident safety advantages to the rider, and engine longevity. Another words, it prevents wheelies from the get go or quick downshift - like R6 loves to do.

[speediva]

I agree with most of your observation, but the article said something about "it likes to wheelie" under one of the pictures. I'm not sure if the clutch plays into that or if it was just a wheelie under power. I don't know much about slipper clutches since all they said was that it is like the one from the RR last year. I know the sales lady made a point to mention the slipper clutch when I sat on one, but I don't think she knew any better than I did as to what it does.

[Z_Fanatic]

I think slipper clutch is basically what the name implies, it allows the clutch to slip, autonomous managing of the power shifted into the rear wheel. The clutch plates are lighter and set up in a way that the actuators control the power during over-rev down-shift. Another words, it's a great gadget if you're someone who brakes/slows down late. Slipper clutch system can be fitted to both dry or wet clutches, but Kawi refers it as a back-torque limiter fitted on a wet clutch.

For example, if you're in third gear going 10K in the rpm range, and suddenly you have to downshift to decelerate fast and take the bends. But if you don't blip the throttle to match the rev with the wheel speed, chances are you'll either wheelie the bike (older R6 loves to do that during deceleration) or lock up/hop the rear wheel. With the slipper clutch, you blip the throttle ridiculously little, or a lot, doesn't matter, as long as you blip, and back-torque actuators will work to your advantage synchronizing the engine speed with transmission. So no matter how careless you are, you can't get the rear-wheel to lock during high-rev down-shift if you have slipper fitted - at least that's what Kawi implied. You can be hard on the throttle until the last second, then disengage the clutch, blip a little, and let the magic work. Journalists reported that you know it works when you feel the clutch pulsating a bit.

But this is good for track sort of thing, when you're in the crazy power-band, 10K and up. The ZX-6RR had it fitted in 03, then in 04 it came with a racing kit, and now the 05s have it standard on both models.

[NaKeDZX]

Slipper clutch only works on decel to prevent wheel lock up. It has no effect during acceleration.