Slipper clutches

[duke63]

Been reading up on the Sigma website.

Anyone know what the difference is for a 38 degree ramp compared to the standard ramp angle? It doesn't seem to say. All I can see is a 38 degree ramp clutch is more expensive.

Also the site talks about using a slipper clutch to make downshifts clutchless. Whilst I can understand some of the logic here, why would you want to do it, other than in perhaps a race situation? Surely it is a poor subsititute for matching revs or an autoblipper?

http://www.sigmaperformance.com/slipper-clutch-faq.html" onclick="window.open(this.href);return false;

[DaytonAndy]

I assume the different angle changes slightly how the clutch engages? Probably more racing biased but not sure really. The slipper clutch is mainly to stop the rear locking when you go down the gears. Obviously throttle matching or an auto blipper would be better but when you're HARD on the brakes it's not easy to blip the throttle at the same time. I've had a situation on the road when I've locked the rear under hard braking when I was chasing an R1 on roads I didn't know and it fish tailed which was fairly unpleasant. The bloke following me said it looked awesome but in truth I was fairly lucky to get away with it! If I'd had a slipper clutch I probably wouldn't even have realised there was a problem as it wouldn't have locked. 99 times out of 100 you'll probably never use the slipper bit it's nice to know it's there in an emergency.

[Monty]

I'd forgotten to notice I'd got one, but thinking about it I've not had fishy tail moments!

No idea on the ramp angle Duke, new one to me.

[D41]

If memory serves the 38' degree is much more 'severe' in it's operation.....more of an on/off switch than a normal clutch.

Clutchless downshifts are easy to do, but brutal on the internals if you feck them up.

They're also handy if your clutch cable snaps on the way home from a ride and you don't feel like pushing your bike the last mile because you stalled it on a side street and had to walk home when it finally died.

In your leathers.
In 90F weather.
Like a dork.

I'm sure someone asked this question not too long ago.

[Blade]

You can sometimes feel the slipper operating as feedback through the clutch lever. Had this on both my Blade and SP2.

[Kwacky]

The zx6r has one as standard.

[duke63]

My Multi has one but I have never felt it working.

Is there a difference with an aftermarket slipper in that perhaps they are more track orientated?

I know what they are there to do but don't know much about how they work and how you can vary the slip. Sigma claim there clutches can be adjusted.

[Monty]

The zx6r has one as standard.

Assuming that was meant for me. I knew it had one when I bought it, but had forgotten to give it a thought while riding it. Probably a good indication that it works!

[Kwacky]

Yep Monty, it was.

It was a pain switching from the zx6r and the z1000sx as the 6r had the slipper but the SX doesn't so I've had times when I dumped the clutch on the SX and got a sharp reminder.

[kiwikrasher]

My Multi has one but I have never felt it working.

From what I've just read Duke the Multi clutches aren't a traditional mechanical slipper clutch but a servo operated mechanism that decreases clutch pressure on overrun giving a slipper-like operation. For my part I didn't even know it had a slipper function until you mentioned it, but once you did, I realised I have never felt it NOT work, which is usually for me, more apparent!

Torque assisted slipper-clutch - The Multistrada 1200 features an oil bath clutch with ‘slipper’ function and super-light feel at the lever. Its design uses a progressive self-servo mechanism that presses the plates together when under drive from the engine, enabling the reduction of the clutch spring rates. This results in a much lighter clutch lever at the handlebar, ideal in stop-start traffic or long journeys. When the drive force is reversed (over-run), the same mechanism reduces the pressure on the clutch plates, enabling them to provide a race-like ‘slipper’ action, which reduces the destabilizing effect of the rear-end under aggressive down-shifting and provides a much smoother feeling when closing the throttle or down-shifting under normal riding conditions.

Now I want to find out more about this self-servo mechanism...

[kiwikrasher]

Been reading up on the Sigma website.

Anyone know what the difference is for a 38 degree ramp compared to the standard ramp angle? It doesn't seem to say. All I can see is a 38 degree ramp clutch is more expensive.

Also the site talks about using a slipper clutch to make downshifts clutchless. Whilst I can understand some of the logic here, why would you want to do it, other than in perhaps a race situation? Surely it is a poor subsititute for matching revs or an autoblipper?

http://www.sigmaperformance.com/slipper-clutch-faq.html" onclick="window.open(this.href);return false;

You got me interested Duke so I've done a bit of reading. This bit seems to explained it for me

For really big differences in clutch feel different ramp angles are required; on supersport engines, 600cc ones we use ramp angle of between 37 and 33 degrees depending on bike. For some bikes, such as the Honda CBR600RR, we have clutches available in 37 and 33 degree angles depending on power out put. This is because lower angles are better at dealing the stronger main springs required to transmit high power outputs under acceleration. All these lower angles mean that the clutch will slip when bump starting is attempted so electric starters are required.

Historically we have used 45 degree angle ramps on the larger bikes. This is because most were bump started in a racing environment. Now however race teams are leaving the electric starter mechanisms on so we are reducing ramp angles in the pusuit of a significantly smoother action than any of the OEM slipper clutches.

[kiwikrasher]

Now I want to find out more about this self-servo mechanism..

So it appears its a fancy name for a simple added design feature. The faces that drive from engine torque have a reverse angle on them that pulls the clutch together, meaning they can then use lighter springs for the same power output, giving a lighter clutch lever feel. Simple but clever.



This is a picture of the kawasaki version but from what I've found and read I'm guessing the Multi clutch is similar.