Regarding changing clutch slave cylinder with AM one

DarkMonster620 · February 20, 2012, 12:54:58 PM

Hi,

I replaced my clutch slave cylinder, Oberon, and pick up is almost instantaneous, but, lever is hard and neutral is very hard to find.

Using coffin clutch master, smaller sized one, bike is a M620Dark

Any help would be appreciatted . . . Cannot ride like that in traffic . . .

Thanks

Carlos
dm620

stopintime · February 20, 2012, 06:28:55 PM

The Oberon is 29 mm and that means that lever travel is quite a lot longer (and lighter)

If the point where the lever actually starts pushing the master cylinder is off, it means you won't be able to disengage the clutch completely. Aftermarket levers adjusted too close to the bars will have the same effect. Another cause for this can be air in the fluid and/or bad fluid, which can be fixed with new fluid and/or a bleed.

I'm not sure if your lever has any adjustability, but if it does it will look something like this and a tutorial can be found here (scroll down) http://www.ducatisuite.com/leverchange.html

DarkMonster620 · February 20, 2012, 06:38:14 PM

Thanks stopintime, I do have adjustable levers set at 2[not to far not to close], new DOT4 fluid.

No matter where it is, the lever, it will engage almost instantly, but, cannot find neutral and riding like this is very tiresome.

Have already located a set of new masters, radial, to replace my aging coffin masters.

BTW, didn't know Oberon was 29mm, thought it was less . . . Shall I go for a smaller one? 28mm? Or difference will be negligible?

stopintime · February 20, 2012, 06:53:57 PM

Well, then my guess is that you're missing a few small turns on the lever plunger adjuster (in my picture) Enough to disengage properly, but still a couple of mm free lever pull before it starts disengaging.

First try and see if the lever adjusted all the way away from the bar will help finding neutral. If it does, we're on to something.

As it is now, you're wearing out the clutch prematurely - need to avoid that too.

My opinion is that the wet clutch has a light enough pull with stock slave, but I have a YoYoDyne 28 mm on stand by. It won't be put on yet, so I can't say if 28 mm is correct. Adjusted correctly I think it will be.

DarkMonster620 · February 20, 2012, 06:55:17 PM

OK, I'll check tomorrow . . .

DarkMonster620 · February 21, 2012, 07:45:08 PM

Ordered new RCS 16 mm master . . .

DarkMonster620 · February 22, 2012, 04:50:43 AM

Thanks for help . . .

Slide Panda · February 22, 2012, 12:23:30 PM

The root of your problem is probably due to the larger bore of the new slave. In a closed system like this if you change one measurement, something else has to change to compensate. Each lever pull you're pushing a set amount of fluid to the slave and a piston in the slave moves as a result. IF you increase the diameter of the piston, it will move less. volume=pie*height*radius squared.

So the slave piston isn't moving far enough to fully disengage the clutch stack. You can get some more by fiddling with the adjustment mentioned - just keep in mind that you do need some free play. If you adjust it too far in it won't clear the fluid return hole and you'll slowly pump up the clutch, and it won't engage.

But, if you've or are fitting a bigger pistoned master, that'll help.

DarkMonster620 · February 22, 2012, 12:29:22 PM

stopintime, Sad Panda,

Thank you both for your input; I tried stopintime's recommendations and it was almost the same.

Reason for replacing, is that we have lots of hills here in the city, many stop lights are going up, many stop signs are also going up and with the OEM slave I was either stalling finding the 'grip' on the clutch and then playing with the gas to be able to continue.

Anyways, I thank you both again; as said a new Brembo RCS16mm clutch master has been ordered.

Slide Panda · February 22, 2012, 12:52:49 PM

I hope things get better for you - but they might not.

The clutch in the 620 and other models with the APTC Clutch are known to have a smaller friction zone that is near to the end of the levers sweep. It's an attribute of the clutch design

DarkMonster620 · February 22, 2012, 01:29:54 PM

Quote from: Sad Panda on February 22, 2012, 12:52:49 PM
I hope things get better for you - but they might not.

The clutch in the 620 and other models with the APTC Clutch are known to have a smaller friction zone that is near to the end of the levers sweep. It's an attribute of the clutch design

On 620 from 2005-2006 and then on the 695 ... Previous year 620s don't have this issue so 'marked', I know cause I take care of 2 M620 from 2004 ... they grab a bit earlier ...

ShiftSix · February 23, 2012, 07:27:24 AM

I had this same issue when I added the same oberon slave cylinder and new levers. Turns out the plunger in the lever needed to be about a 1/4 turn out further. Instantly solved the problem...

Picture of what I am talking about.

best of luck man,

DarkMonster620 · February 23, 2012, 07:31:09 AM

Quote from: ShiftSix on February 23, 2012, 07:27:24 AM
I had this same issue when I added the same oberon slave cylinder and new levers. Turns out the plunger in the lever needed to be about a 1/4 turn out further. Instantly solved the problem...

Picture of what I am talking about.

best of luck man,

Issue is, I had to go back to the OEM coffin master . . . And there the issues started

ducpainter · February 23, 2012, 09:08:16 AM

There is an adjuster on the coffin lever too.

Be careful...it also adjusts the return of fluid to the reservoir.

DarkMonster620 · February 23, 2012, 09:10:17 AM

Quote from: ducpainter on February 23, 2012, 09:08:16 AM
There is an adjuster on the coffin lever too.

Be careful...it also adjusts the return of fluid to the reservoir.

I know, . . . havent touched it!

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Regarding changing clutch slave cylinder with AM one