quite a while ago I spoke to a guy at sigma who said the ramp type need regular greasing of the ramps for them to work effectively. He said the bearing type are far better, less greasing, not as harsh in operation.

ah, that will be dear old Neil Spalding .....

Nelly has a brand spanking one in that he'll do a deal on ... STM jobbie ..

Mines got balls !

not what yer missus says ....


Adam, if you really must have a 12 tooth one with balls and ramps then just call Sigma and get your moth eaten wallet out .....

The main difference is the maintanance intervals, a ramp and ball type typically needs a re grease at every 6000 mile service, where as the "pukka" Ducati Course type are designed with a strip check and re grease between meetings or every few hundred miles, with ramp only type being a bit longer, so it all depends on how offten you want to be checking it, if you are a road rider then obviously you dont want to be messing every other weekend or once a month.

Hope this helps Steve and I`ll see you at some circuits no doubt.:sing:

I think you might be confusing centre spring jobbies versus ball and ramp Weeksy.

It's still really only one type - it's just that the later STM Evoluzione ones use a single central (larger) spring rather than a number of individual posts with associated springs.

The idea of the single central spring (STM call it a diaphragm spring) is to allow them to make the engagement of the clutch more progressive and to give better feel. It also reduces the weight of the clutch components.

All of them use ramps to disengage the drive under backwards torque, and some combine the ramps with ball bearings to make this action smoother - note that you would not normally "feel" the ramp action in everyday use (ie, when pulling away or changing gear) as it only kicks in to stop the back wheel locking up.

You've then got various designs of clutch basket, from the stock 12 tooth basket to the STM like 48 tooth basket. This spreads the load of the plates over 48 faces rather than the standard 12, which in effect gives you only a quarter of the wear rate on the basket.

Basket materials also make a difference. Most aftermarket ones are alloy, sometimes hardened or anodized (which is not always the same thing...) and the idea here is to reduce rotating mass of the clutch and help things spin up quicker. The only problem this creates is the mismatch between basket material and clutch plate material can lead to increase wear on the weaker material - ie, an aluminium clutch basket with oem steel plates means more wear in the basket. This is another reason to match the basket material with the clutch plate material, for example the ST alloy plates.

As an aside, I have used both a stock and an early STM 6 post ramp & bearing slipper in the 748. I also have an STM Evoluzione sitting in a box for the last year that I have yet to fit!

There is a marked difference between riding a bike with and without a slipper clutch, in that it gives you so much more confidence to brake deeper into the corners without fear of locking the rear wheel.

It will be interesting to get the STM in the bike and see how that feels on the track, and whether it's a big improvement over the 6 post ramp & bearing one.

Antonye, are you looking to change your user name to Shazaam2?

[Edited on 17-3-2005 by Felix]

he's more likely to change his name to "Sharon" ..... :lol: