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Lost clutch pressure?

R

r896neo

Joined Jul 2008
167 Posts | 0+
Belfast
Hey whilst riding today the clutch lever suddenly started losing pressure and coming further and further back to the bar before biting. It went from normal to floppy lever and hardly biting at all within 2 miles. Was close to home and bled it when i got home but cannot get any pressure in the system. Fluid had obviously leaked onto the bellypan from the clutch cylinder (the engine cylinder where you bleed it)

I'm thinking its a seal gone somewhere in there but i couldn't see or have time to take it apart as it was getting dark and i have no garage. This is my daily commute so any ideas on a what may have gone so i can get onto it quickly.

Cheers.
 
have you tried bleeding at the bleed nipple attatched to the clutch lever thats where mine normally collects air as this is the highest point...just a thought....:thumbup
 
No but there is no pressure there at all, its not just slightly spongy. The whole thing was a sudden and rapidly deteriorating event which has me pretty sure its a seal somewhere in the slave cylinder.
 
If you have fluid in your belly pan then the slave cylinder seal must have failed or the banjo union has come loose.

Check it's not the union, if that's ok then take this opportunity to upgrade your slave cylinder.
 
No not the union, that i could clearly see. Must be a seal in there somewhere. Will pull it apart tomo.
 
It will probably be the piston seal in the hole the pushrod fits into.

Chances are if you take the slave off the engine you will be able to see that it has leaked past the pushrod and run down from there.
 
no way the exact same thing happened to me this morning on the way to work today, only bled it a few weeks back aswell,
 
MPL Tuning Billet Slave Cylinder is the best money spent...go'oorn ya know ya want to!
 
This is a common problem with the RSV due to slave clutch construction. Air from the engine is forced into the slave clutch hosing. Also the reason for the fluid to turn black.

AF1racing.com have a good after marked slave clutch.

Bleeding prosedure:
If you have an 04 or later RSVR or other model with the OEM Brembo radial clutch master cylinder the position decriptions above do not apply and you will need to do some additional bleeding/Purging to bleed out the master cylinder itself through the bleeder there. You can do this in either of two ways.

1st) Put a length of your vinyl tubing on the bleeder at the MC, open the bleeder, pull the lever to the grip, close the bleeder, release the lever. Repeat several times till there is no air.

2nd way) Attach your syringe, full of fluid, to the bleeder on the slave cylinder. With another length of tubing on the bleeder on the MC, open both bleeders and inject the fluid up through the system. Obviously with both methods you'll want the loose end of the tubing from the MC bleeder in some kind of container.
 
terje said:
Air from the engine is forced into the slave clutch
Click to expand...

You sure about that.

The reason it gets air in it is cos the seals get dirty from chain lube etc and wear and so hot they turn to mush and allow air past.

There isn't any air coming from the engine itself.

The fluid turns black from the seal/metal type used in the slave.

No cheap Uk source. Still waiting on Uli to come back with a deal on MPL.
 
foooker dont get bringing the hammertime in the equation!! i told you id let you win next time we were out :laugh
 
Can't quite manage the Cash for the billet so just got a gasket enroute.

Cheers y'all
 
Changed the original clutch slave cylinder twice since 2006, but I still had to bleed after just 1000km. My local Aprilia mechanics told me that the original piston seal (only one)works one way, which means it prevents brake fluid to leak, but not the opposite direction.

Have just bought a Evoluzione Billet Clutch Slave Cylinder. The piston has 3 seals to prevent leak. I will install it soon and report how it works. I'll be back...
 
Thanks all for advice but changed the gasket within the slave just now, took 20 mins and its sorted. A+ for next day delivery from Ultimate parts (formerly aprilia yorkshire)

That allen bolt inside the fairing stay rod thing was a *****!
 

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