Hydraulic Clutch Issue

Team Strada,

Have a strange issue with my clutch. It's a hyd swap on 2013 and I've been running it for a year without issue. Recently, I noticed difficult engagement in the low gears nearing the end of my route. I have to stop and show a badge and new right away my clutch was gone. Pushed it to a garage since I couldn't engage without stalling in 1st or 2nd to pull from dead stop. Figured this must be air in the system from my experience with car clutches. Also, the clutch pack is relatively new, maybe 7K miles. Came back a day later with tools to bleed the line, which is extremely easy on my Ducabike setup. Did notice some fluid weeping from the reservoir but I did check the fluid a couple weeks ago and assumed I just didn't clean up very well. Reservoir was full and I got to work bleeding. Lots of bubbles so thought I was on to something. Got it pretty clear and no dice on op test. Put almost half a bottle of fluid through it with op checks in between. By this point, it was spitting atomized bubbles which I couldn't determine if they were from the running motor or vigorous actuation of clutch.

Eventually got it drivable, but not 4.0. Still walked pretty hard in first, clunked into gear, impossible to find neutral and there wasn't much friction zone with a very shallow and abrupt bite. On the way home, it just magically went back to normal. After a week, I've had similar instances of it going back to rough, but not disabled. It seams that if I just ham the clutch lever a bunch of times and shake the bike like I'm an ape trying to get to a banana under the seat, it gets better again. Don't think it's running temp related, but still testing.

Gotta be air in the system, right? Think I'm just gonna order stainless lines since never did it and they have some age (brake side). Any thoughts welcome.

Nick - It's Ducabike kit, not Ducati. The lines are nothing fancy but the slave is very high quality.
Tim - I didn't even think about adjusting the throw. My ASV shorty's are adjusted pretty close to the knuckle.

Either way, I have a leak for sure. Reservoir was at min when I rode home tonight. Leak is not at the reservoir, initial lines, or the slave area. I can't find any witness areas but it's been raining a lot. Gonna order some braided lines and will have to investigate this weekend. Kinda shocked it still works as is. What damage do I have to worry about if I run it a little longer in this condition? I'm taking it slow and using the QS when I can.

I installed myself and was confident fluid couldn't get past the actuator-to-pushrod junction. I'll check the slave but there is no fluid leaks anywhere. I had some funny smells coming from engine but I just cleaned it recently and thought it was my polish burning off, common from overspray on the exhaust. I ran my finger along the line from the lever to as far into the frame as I could and dry as a bone. Perplexing...

Overtightening is my middle name. Sounds like new lines is a decent place to start.

Nik - It's a very low shelf Brembo with full metal box reservoir integrated into the lever assembly. Spitting image of the OEM brake system.

I'll probably pull the whole thing apart this weekend. Not finding an obvious leak has me scratching my head.

It stopped raining and I can definitely now smell a fluid dripping on the engine or burning on some other hot part. There's only like a 10" section I can't inspect that runs through the frame. This is perplexing...

hyperbruno said:

An spinning push rod can cause slave cylinder failure. Does yours have the anti-spin pin on the slave cylinder end?

Click to expand...

I'm not sure but have determined it's definitely the slave cylinder or pushrod actuation. There is no leak. I don't recall a pin on the rod. Adjusting the lever throw all the way out helps, so it seems I'm not getting enough travel on the pushrod (the tremendous adjustment range of my ASV levers really helping out). If that's the case, I can only assume the slave piston is malfunctioning or damaged.

The slave came apart as I removed it. Like, the case came off and the piston assembly stayed somewhat attached to the rod. This could be bad seals or it was just under pressure (didn't release pressure first). Just gonna clean and lube, maybe replace the spring since I might have a good replacement. Don't know about the seals. They are unique. I bought what I could find at the hardware store and some better fluid. Let you know when I get it back together.

I'm at a loss. Rebuilt and bled about 1/4 pint of new fluid through it. Prepping/purging the slave confirmed all the seals are good. Still had a few bubbles towards the end but tension in the lever felt very good. Used full throw of lever. Upon first test, same. I pumped the lever in neutral and it seems to function normally. Adjusted lever throw back to preferred setting and it held.

I've got a power bleeder in the mail and will give it a proper flush when that arrives. I wish it was just some air in the system, which my bike has been notorious for (see my rear brake thread from 2015). But it's probably still shifting like **** and missing 4th-5th under hard acceleration, with or without the quick shifter. I can feel it grinding the cogs a little if I don't really but my foot in it and forcefully shift up. Downshifts seem to require more effort than normal, too. And the clutch shouldn't affect the QS operation at all, right?

I just don't get it. After first install of QS, everything was amazing. Just perfect, low effort flicks of the toe and it was banging up the gears at full chat. Literally just messed with the sensitivity settings in software, then dog crap. Think I got a new pair of boots at the same time and thought I just needed to adjust the shifter position. Nope. Then noticed the locking nut on the haim bolts-QS solenoid had backed off. Nope.