Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Sport Touring: ST4 / ST3 / ST2 > wet or dry clutch??

[Dunks]

Can someone explain in simple language what the difference is between a wet and dry clutch? My ST2 has a dry clutch, but I don't know what that means. In terms of performance, what is the difference - if any?

Thanks!

[HW]

Wet clutch = runs in oil
Dry clutch = runs dry - many seen with vented covers like this

http://82.70.86.166/handk/images/bik.../100_0625a.jpg

The original dry clutch cover as seen on the 4Valve engines plus some 2 valve ones like ST2, is a conical bolted on cover. The wet clutch has been used on modesl such as the 620 Monster and is cast as part of the casing. Don't think there are other variations, but i am no expert so willing to be corrected.

As for differences - the dry clutch is a racing design, should give more grip but will wear faster and is noisy (hence the trademark Ducati rattle) and can get very hot (i.e. in hot weather in traffic). The wet clutch is quiet, less snatchy, will not wear as fast but will (probably) not give the grip.

Wet clutches are likely to become more common on future models due to the stricter EU noise regs coming in.

There is a bit of difference between the standard clutch on the ST2 and the later ones, in that the ST4 used a lighter clutch basket. That helps in terms of letting the engine spin up faster because it has less rotating mass. As for pressure plates, I think they might be the same though, but not sure. If they are, I might have a Casoli red pressure plate and stainless srpings going spare in a few days because I am changing to a slipper clutch that doesn't use them.

Hope that helps.

[Edited on 10-9-2005 by HW]

[rockhopper]

Two reasons for a dry clutch, one is the reduction in drag as the plates are not spinning round in an oil bath, two is that as the plates wear the debris is not carried around the engine in the oil and therefore passing though all the bearings and wearing faces etc (which is a bad thing).

I think the ST2 and ST4 share the same set up, the ST4S has alloy friction plates (which i am now running in my ST4, they are so much quieter). All three bikes run a steel basket.

I'm currently on over 15,000 miles with my clutch but i've had to clean it out at least three times incuding de glazing the steel plates twice, i dont think there is too much more life in it. Wet clutches are pretty much good for the life of the bike these days.

Amongst other Ducati "characteristics" the dry clutch is one that i would gladly do away with!

[Dunks]

Thanks guys.. very informative!

[Carbon749]

Originally posted by rockhopper


Amongst other Ducati "characteristics" the dry clutch is one that i would gladly do away with!

What and lose that Ducati rattle with an open clutch cover .... never

[Iconic944ss]

Good Q&A guys....

I knew the principles but always wondered how the 'wet' clutch manages to work well at all, does it use different friction material? or - why does the oil not soak into the material and drastically reduce efficiency?

I still like the death rattle of an open cover clutch

Frank

[Mad Dog Bianchi]

kind of like a spongy cork material that soaks up oil, but is subjected to enough pressure to ensure grip. Release the pressure and the material can slide on the metal plate surface with very little friction.

[Derek]

Originally posted by Iconic944ss

I knew the principles but always wondered how the 'wet' clutch manages to work well at all, does it use different friction material? or - why does the oil not soak into the material and drastically reduce efficiency?

Wet clutches are generally larger with a greater surface area of plates to enable them to grip even immersed in oil. This of course means they are also heavier - another reason to stick with a dry clutch.

[TP]

I much prefer the dry clutch rattle to the characterless wet clutch I have on my monster.

As many Dd'ers will attest, we had issues with clutch slip on the wet clutches and we've tried various differnt things to load the clutch more, including stiffer springs and extra plates etc. Running a fully synth oil doesn't really help and we've mooted running a semi-synth oil to help with this. Fortunately I'm not suffering clutch slip anymore so I didn't have to go down this road.

Dry clutches are much better IMO.