Losing Clutch Presure.

[Mr C]

Fitted a new oversized Slave Cylinder as the old one just seems to seise up a few weeks ago. Everything was fine for about 20 mins till I came to some trafffic and ended up with no Clutch at all, Just a lose lever. Had to ride home with no clutch. I had fitted the Slave cylinder correctly and bleed it properly.
I got home and bleed it again, it seem to work ok for a short while them loses all presure again and no clutch.
I did notice some fluid up near the Master Cylinder, So im thinking it must be the master cylinder that now needs replacing. Do i have to buy a new one or is there a refurb kit i can buy?

[keefer]

if its not the master cylinder are you sure that the hose is connected at both ends correctly ?.
have another good look for fluid at either end of the hose

[madmav]

Did you need to fit the longer pushrod?

[Mr C]

Originally posted by madmav
Did you need to fit the longer pushrod?
Dont think it is the Push rod as it was fine to begin with.

[keefer]

if you have gone from the old style slave cylinder to the new, Then you will need the longer push rod, if not then its not that.
obvious I know :o

[Mr C]

Originally posted by keefer
if you have gone from the old style slave cylinder to the new, Then you will need the longer push rod, if not then its not that.
obvious I know :o
Well its a 1999 996 so would i need the longer push rod?? But why would the clutch work for a while rather than not at all??

[keefer]

I would imagine that it had the longer push rod in anyway,
does the slave cylinder look the same as the old one ?
other than that I can only guess that its due to the metals getting hot in the clutch plates and expanding just enough to make it inefficient.
but again if its not the push rod which it sounds like it isn't. My only other idea is it is leaking fluid from somewhere. Sorry. not much help really.

[Mr C]

Originally posted by keefer
I would imagine that it had the longer push rod in anyway,
does the slave cylinder look the same as the old one ?
other than that I can only guess that its due to the metals getting hot in the clutch plates and expanding just enough to make it inefficient.
but again if its not the push rod which it sounds like it isn't. My only other idea is it is leaking fluid from somewhere. Sorry. not much help really.

Its going on a trip to Nellys next week so i'll let he have a play with it.

[keefer]

sounds like a plan

[TopiToo]

Hello Mr C

I have had the same problem, with my oversized Slave Cylinder, I drained the clutch fluid, topped up the reservoir then took the cylinder off and pushed the piston back into the cylinder, be careful as air/bubbles will work there way back into the fluid reservoir I think this is called "back bleeding" then pumped the lever with the bleeder valve on the banjo bolt slightly undone, topping up as you go.

Saying all that I noticed that once all tightened up when the lever was pulled I could hear a hissing noise coming from the cylinder, which would suggest air is getting out/in.

I think its coming from the cylinder onto the crank case, not sure yet as it got to cold last night. But seems odd to have a compressed cylinder with no seals onto the crank case. (metal on metal so to speak)

I replaced the pushrod for the longer one.

When I know more will let you know. Sorry not much help I know, but it must be the cylinder end air is getting in:puzzled:

regards

TopiToo

[Mr C]

Mine is not the Metal on metal type. It has a rubber bellow, there is no fluid escaping or any air hissing. :puzzled:

[DAVE HARRIS]

I would check the clutch pressure plate bearing where the pushrod fits into the pressure plate. I have seen it before, the bearing partially siezes and spins the pushrod which twists the piston in the slave cylinder which then retracts and allows air in. the bearing should be comlpetely free.

dave

[Fordie]

Ive just fitted the Cornerspeed Slave cylinder ,I did not have to change the pushrod on my 98 996.There was a small rubber washer that sits between the slave and the casing that the pushrod sit through,if thats been split it could allow air in maybe. Sounds like a leak of some kind, maybe try a splash of weak fairy liquid and water mix around the joints to see any bubbles appearing. 4D

[rockhopper]

I might be wrong but i think the slave cylinder is a sealed unit in its own right, it doesnt need to be bolted to the engine to work. Of course if you operate the clutch lever without the cylinder bolted to the engine then the piston will pop out. All the rubber bellows things does is stop chain lube etc getting all over the piston. Mine split and dropped off ages ago. I must replace it one day!

[Albie]

I had a problem on my monster 900 like yours. I even bought a new master cylinder. And slave cylinders. Borrowed two of Nbs. They were fine.
There was still air trapped in pipe. You need to tip the bike over to the right as far as fluid wont pour out and bleed. It works everytime for me since at least 3 times as I tried new hoses since. It been good now since July:)

[simonducati]

I had the same problem but I found out the hard way, the push rod could be spinning and damaging your slave cylinder , this will course your fluid to go black in the master cylinder to because of the o-ring rubbing in the slave cylinder.

[FiscusFish]

Like Albie my money is on air in the system... It can be a right pig to bleed it completely. Make sure you use a brand new unopend bottle of fluid too. Brake fluid absorbs water as it sits on your garage shelf.

Darren

[Old Yella]

Hmm
I had a similar problem on the 996 and when Nelly stripped it down at the 12K service he found a seized clutch pressure plate bearing and a snapped push rod as it goes through the casing, still workwed but when I lost pressure I just pumped it a few times and all worked nearly fine but seemed to free of if parked for a while which makes me think it was a sticking pushrod?
Poss caused by the split rubber?

Nelly will sort for certain when it gets there, worked for mine.