450 Clutch problem

M

mike989

New member
I replaced the fiber plates on my 03 FSE, everthing went fine, I thought. I blead about a 1/4 can of new dot4 fluid through the system. The clutch had full resistance, felt fine. Started the bike let it warm for a minute, pulled the clutch lever, and there was no resistance, nothing. Shut the bike off to bleed the system more, and there was full resistance again?? I've now bleed more than a 1/2 can of fluid, and I get full a full stream of fluid each lever pull, no bubbles. Now the clutch works while the bike idles, but goes away during the shift to second, no resistance at all, let the bike idle, and the clutch comes back. :confused:
I'm thinking the traditional bleeding sequence is not working for hydraulic clutches. Is air causing this, if so, how much air and where is the air hiding?
Anybody else have this problem with hydro clutches?
 
there should also be a adjustment in addition to bleeding it, also make sure your slave cylinder is not bypassing and not holding pressure, but it sounds like to me that you have some clutch dragging, and it may be fine when idling(motor not pulling) and when shifting revving the motor it drags and is not fully disengaging.
 
TripleThreatMotorsports said:
there should also be a adjustment in addition to bleeding it, also make sure your slave cylinder is not bypassing and not holding pressure, .
Click to expand...

Like it was mentioned, make sure your lever adjustment is backed off fully.
Bleed from the bottom to the top with a hose and syringe. That is the only way to be sure you get all the air out....
 
You will find that the piston on your slave cylinder is being pushed back.
Two things can cause this. Running to thick an engine oil. (should be 10w40)
or the spring behind the piston on the slave cylinder is to week.
Gas Gas updated this spring in late 2004 to a heaver spring.
I bet if you take your master cylinder cap off start the bike and rev it you will see fluid being forced up, because the piston is getting pushed back.
If the engine oil is to thick a grade it builds to much pressure down the main shaft and pushes the piston back.

Note: If you purchase a new slave cylinder kit is is the two stroke part number and has a weeker spring in it so you will need the updated spring to go with the kit.
 
Thanks for the replys. :D
The clutch works fine while the motor is not running, so it's not a lever adjustment or drag problem. It has less drag now with new plates than with the old plates.
I use Rotella 10-40. I had the resesovir cap off the whole time I was bleeding, running and not running, and got no blow back. I will check the slave unit spring.
It's got to be air in the system, but you'd think after 10-12 oz of new fluid the air would be gone. I'll borrow a vacuum type bleeder.
 
i am not up fully on gasser cluthes but my experience with cannondale hydraulic clutches they only reccomend a mineral oil something like magura blood I thinks its called i run a hyd clutch oil mineral oil in the ones I have the clutch oil is not much thicker than brake fluid it may be too thick and not flowing through the lines properly.
 
TripleThreatMotorsports said:
i am not up fully on gasser cluthes but my experience with cannondale hydraulic clutches they only reccomend a mineral oil something like magura blood I thinks its called i run a hyd clutch oil mineral oil in the ones I have the clutch oil is not much thicker than brake fluid it may be too thick and not flowing through the lines properly.
Click to expand...

Gasser clutch hydraulics use brake fluid not mineral oil, always check the top of the master cylinder to confirm..
 
Sandman said:
Trust me I know the heaver spring will fix it.


Sandman,
I can't see a spring clearly in the exploded drawing of the slave unit, and have not taken mine apart yet. I haven't located a rebuild kit.
What does that spring do?
Does it control a check valve?
If it's a check valve spring, I could see, under engine vibration allowing the fluid to bleed back to the reservoir.
Click to expand...
 
The spring is behind the piston in the slave cylinder.
The books are crap and may not show it.
I will try and find the part number you will need, because it is not the one in the kit.
If the spring is week it cannot hold the piston agenst the push rod and it gets pushed back by oil pressure. Thats why when you are at idel you have clutch(low oil pressure) and when you build up the revs you have no clutch.
(greater oil pressure)
Some times on cold days the oil is thicker untill the bike warms up and you can have the problem at idel as well.
When you replace the spring its best to replace the o-rings as well.
 
Yes please, if you can find the part number that would be great.
I thought hydraulic fluid pushed and held the piston against the push rod. I guess I need to take mine apart to see what it looks like inside instead of guessing and talking about it.
Thanks.
 
Yes the clutch fluid pushes the piston agenst the push rod but when the piston has been pushed back it will have no pressure, just like when you push the pistons back when changing brake pads, but because of the week spring
it keeps pushing the piston back when you let go of the leaver. Brakes dont need a spring behind the piston because they do not have oil pressure trying to push the piston back in all the time.The spring is only to hold the piston agenst the push rod so the piston has not got 3 or 4mm of travel before it contacts the push rod.
If your dealer has not got the correct part go to a auto shop and see if they have one a bit stronger than the standared one.
I will find that part number ASAP 1st.
 
Sandman,
I've got a spring and a seperate rebuild kit on order.
In the mean time I took the slave unit off the 03 and put it on my 04 EC300, and the clutch works just fine. I took the 300 out for a couple hour ride today, and never missed a beat. The 03 acts the same way with the 04 slave unit on it.
I didn't pop the pistons out to compare springs.
I use Rotella 5-40 in all 3 GG bikes.
 
Mike,

Have you tried riding it?
I had some strange problems on a Honda road bike after changing fiber plates. The clutch would only just disengage and dragged a lot. After riding a little while and using the clutch it all settled down and went back to normal. I put it down to the fiber needing to wear a little and things to settle. Until it did the actuating rod had nothing to push against until the very last bit of lever travel. Only took about 10 miles and a few takeoffs to settle back into place.
 
Yes, I've ridden it around the neighborhood for 10-15 minutes. I will continue to do that hopefully things will go back to normal.
I soaked the plates in oil over night before I installed them.

Thanks.



I took it out today (1-12-08) with the clutch slave unit still acting up, during the ride the clutch starting working like normal. Don't know why, but it works.
I'll install the 1.5mm spring another day.
 
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