Magura Clutch Reservoir...HELP...Never seen THIS before....

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Joined
Jan 29, 2007
Messages
11
Location
Caledon, Ontario (1 hr N. of Toronto)
I was out riding and my clutch lever action slowly went dead, then pumped back up, then died for good. No clutch.

Back in the garage I replaced the the reservoir piston kit - I was told they wear out from clutch happy racers like me. Took off the slave and cleaned it checked the o-ring, all good, replaced the mineral oil - bled bottom up. Clutch felt fine again.

BUT - when I started the bike the clutch action went away again in under 30 seconds. Then a hissing noise came from the tiny bleed hole in the reservoir followed by a small geyser of fluid!! I took the lid off and the fluid looked like it was boiling - but it wasn't hot - it looked like just air blowing back up thru the clutch hose.

What the heck is this? Help please! :?

BTW - the bike is a 06 fe450 - it is Valterri Salonen's 2006 factory fe450 WEC bike if that matters - but the clutch ***'y is stock Magura .
 
Have you also serviced the slave cylinder? It may be that the slave o-rings are worn also - or that when you bled the clutch you still have air bubbles in the slave..

Cheers,
Simon
 
Bruce when you find out PLEASE let me know, I have been battling for months with the same problem. I have replaced all the o rings, the bleed nipple (they split from over tightening), changed the type of fluid ( magura blood, fork oil, baby oil ), back bled the clutch VERY carefully, replaced the reservoir kit(not the actual reservoir).
Mine fades as soon as she gets slightly hot. I had a post on the site called "fading magura clutch".


I am not the best mechanic, so I am sending it in to get the clutch replaced and hopefully they can sort the fading clutch out.
 
Captain - I sure hope this will not be a "months" problem. I have a packed race schedule. I took it to the local KTM shop yesterday to look at it. Will let you know.

Simon - I have not replaced the o-rings - the bike is an 06 with about 30 hours on it. Should they wear out in such a short time? I refilled the fluid from the bottom up, ensuring there were no bubbles in the syringe hose, then bled it again top down. lever action felt great - until I statred the bike. Did this 3x same results.

I am not losing fluid at the slave. So I am thinking the seals are good. The bleed nipple could be suspect. But what is causing the fluid to blow out the bleed hole at the reservoir?? And i mean it blows out with force.

Crankcase pressure blowing back thru the slave seals?? Or, is air getting sucked in thru the bleed nipple??? Can it be the rubber bootie/seal in the rervoir cover leaking??

thx

B.
 
I have heard of this problem before and this is what I was told was happening.

The slave piston/cylinder is spinning in the housing. Which is what is causing the fluid to get aeriated or foam.

Check the slave piston and cylinder for galling to see if it is indeed spinning. There are a couple of reasons I can think of why this is happening. The bearing in the pressure plate is seized which in turn is spinning the push rod. You should also check the height of the clutch pack to see if the plates are worn out or maybe there is a plate missing. If the slave piston and or housing is galled you willl have to replace both.

The slave piston should only have light contact with the push rod, if the clutch pack is worn down there will be pressure on the slave piston, and if it's bad enough it will be pushed back into the cylinder and with no where else to go will begin to rotate.



Hope this helps,
 
Great info. Is it as easy as removing the slave cylinder to inspect for galling? I have a clutch that feels like it never completely releases. Figure while I'm checking that I'll look at other possible problems.
Lou.

DaleEO said:
I have heard of this problem before and this is what I was told was happening.

The slave piston/cylinder is spinning in the housing. Which is what is causing the fluid to get aeriated or foam.

Check the slave piston and cylinder for galling to see if it is indeed spinning. There are a couple of reasons I can think of why this is happening. The bearing in the pressure plate is seized which in turn is spinning the push rod. You should also check the height of the clutch pack to see if the plates are worn out or maybe there is a plate missing. If the slave piston and or housing is galled you willl have to replace both.

The slave piston should only have light contact with the push rod, if the clutch pack is worn down there will be pressure on the slave piston, and if it's bad enough it will be pushed back into the cylinder and with no where else to go will begin to rotate.



Hope this helps,
 
Magura Clutch Reservoir....the answer...

OK - here's the answer...and the result is so simple because of a huge DUH! on my part.

The vent tube from the head was crimped. Thats it.

Now let me explain. My bike has the vent tube from the head routed up and arching over to the right and then down to vent all the way at the bottom of the frame on the R hand side. It is a WEC factory set up trick supposedly to keep any oil from blowing into the airfilter and possibly carb in the event of a real crash thereby hurting performance. Fry can explain it technically better than I can.

I replaced all the hoses over the winter. ( I bot the bright blue Goodyear hoses from BOSS - but I don't know if they route the head vent hose like I did and would have experienced that) I am guessing that the heat of the first ride sagged the vent hose and crimped it.

Consequently, the crankcase pressure built up and was blowing fluids out the clutch reservoir ( and the water pump gasket , and the head gasket).

Captain - I hope this helps - check the vent hose - do you have a slight crimp. Are you leaking from the water pump or head?

Simon - you were partly right - it was the crackcase pressure that was causing the slave piston/ cylinder to spin and aerating the fluid.
 
RE: Magura Clutch Reservoir....the answer...

Interesting. This was a common problem with KTM RFS models a few years ago if the crank case vent was rerouted. Many people put filters on the ends or one way valves and lost their clutches.
 

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