ebay clutch slave

[freezer16801]

has anyone used a moto wheels clutch slave that can be found on ebay here... Ducati 1098 / 1198 Clutch Slave Cylinder - eBay (item 320665711013 end time Mar-05-11 23:40:54 PST)

They are 30mm and reported to be billet. Cheap too.

[Shazaam]

Aftermarket slave cylinders reduce the lever pull force at the expense of a longer lever pull distance needed to actuate the clutch. The OEM slave gives you shorter pulls, and therefore faster shifts.

This all has to do with the fixed volume of hydraulic fluid

In order to disengage the clutch fully, the plates have to be separated a minimum distance before they no longer touch. This means the clutch pushrod needs to also move some minimum amount as does the slave cylinder piston. The stack has to have the correct height of course. Too thin a stack may result in slippage, while too thick a stack may cause drag.

When you move the master cylinder piston it displaces a fixed amount of hydraulic fluid (stroke volume = piston area times the linear displacement within the cylinder). Since the fluid is incompressible (no air bubbles remember, so bleed completely) this volume is the same that the slave cylinder displaces. Since the slave piston is a larger diameter than the master piston it moves a shorter distance - just a couple of millimeters is enough to decouple the drive and driven clutch plates.

The problem is when you increase the slave cross-sectional area using an aftermarket unit, the stroke of the slave piston DECREASES since the stroke volume is unchanged. As you use larger and larger diameter slave cylinders, eventually you run out of lever pull distance.

So the pushrod moves less and the plates don't separate as far as with the stock slave cylinder.

You can compensate for this effect on some models by adjusting the (4-position) clutch lever so that, in turn, it moves the master cylinder piston farther, increases the stroke volume, and increases the slave cylinder piston displacement.

The larger the slave cylinder diameter you use, the worse the finding neutral problem gets. A 30mm slave is too big in my opinion, but some owners have got them to work reliably.

[freezer16801]

that is some great informative info., as usual. Thanks.

[shanetbird]

don't risk it
get an EVR 30 mm or similar still on US flea bay

A bit more cash but why risk something from China that fails

Ive got a heavy duty spring setup and the 30 mm saved my hands and tennis elbow much grief

shanetbird

[08hyper]

I had installed a 30mm STM right after I bought my bike, everthing worked great untill it started to leak, my dealer said that the STM seal was no longer available for my model, so my buddy at Parts 411 offered me one of theirs, made in China, but really well made, as good as the STM one from what I can see, for less than half the price, I have had it a year now with a DP slipper clutch, works good so far with no issues with neutral. Aloha Alex

[freezer16801]

do you have a link for the chinese made slave?

[08hyper]

Originally Posted by freezer16801

do you have a link for the chinese made slave?

PARTS411 Pomona, CA 1 (877) 484-4860

877 484-4860

Its made by PSR "Ducati slave cylinder" $161.97

Tell em Hypermotard Alex sent you.... Aloha Alex

[AXE]

I have an MPL slave and it has been a good product for 3 years+. I have the red, but don't think the finish is very vibrant and looks dull. I would go for the black if I did it again.

It definitely reduces pull. Bleeding the slave can be a pain, but it can be done. I just changed my fluid out and I managed to get a little air in the line. I still think there is a little in there. The only thing I notice with the MPL, is that with the clutch pulled in and my bike on the rear stand spools, the tire will rotate some, which tells me the clutch pull isn't quite right. I may try and bleed it again. I can't recall if it did this when I first installed it.

Shazaam is right, you will have a little more trouble with neutrals with the bigger slaves.

Here's a link with some good bleeding advice.

http://www.ducatisuite.com/clutch.html

Out!

[shanetbird]

Just a thought a "very old bike mechanic" told me with brakes bleeding on bikes
To get all the last bubble of air out, cable tie the lever in the pulled in position leave over night then release it next day and that will get rid of any air still in the line ?

Did this on the 82 bremo SS front brakes seemed to worked
They where the F^^ked hardest brake bleed job l ever did.
shanetbird

[Clarustnb]

I can second the 'zip tie' on the lever overnight approach. Works great on brakes. [just not TOO tight people]