How Stella got her clutch back - Ducati.ms

mbohn · Jul 19th, 2006, 4:58 pm

Thanks to all the great info on this forum I was able to diagnose and fix a clutch problem on my 749s today.

I noticed a couple of weeks ago that getting down from 3rd to 2nd and 1st while approaching a stop was getting balky. More recently I thought the clutch friction point was getting closer to the bars, but I couldn't be sure it wasn't all in my head. On my ride today I became sure it was the bike and not my head. When I got home I had at least 1" of free play in the clutch lever. I'm close to my 3000 mile service so I considered letting the dealer fix it but decided I wanted it done now.

After searching/reviewing related threads, I bled the master cylinder. After just one bleed, the clutch lever came back to almost no free play! I bled a couple more times and then went down to the slave and bled it a couple of times.

Went for a ride and all is good again. Very smooth getting into and out of all gears. It is especially helpful for blip shifting to have the friction point further out from the grip.

Thanks again for all the help.

Slower than you · Jul 19th, 2006, 5:50 pm

There ya go! A little learnin and tinkerin saved you $80 at the dealer.

mbohn · Oct 2nd, 2006, 9:29 am

Now it appears that I've got to bleed the clutch master cylinder about once per 1000 miles. Defective master cylinder?

**amullo** · Oct 2nd, 2006, 9:44 am

Or defective bleed-valve.. Maybe the O-rings could do with a new set.

//amullo

mbohn · Oct 2nd, 2006, 10:01 am

Is that common on a new bike?

I'll likely have the dealer look at it at the 6000 mile service but it seems odd.

RichD · Oct 2nd, 2006, 12:01 pm

I had a similar problem... but it was the slave cyl. (I started bleeding it there first). If only one bleed got you fixed the air probably was your master cyl., since it got it in one shot.

I put a Yoyodyne in... no problems since.

I hear you can get seals/o-rings to rebuild the factory slave. I'm sure that is a cheaper route.

GJN749s · Oct 2nd, 2006, 12:11 pm

bleed me brakes and clutch at least 6 times a year
only takes 15mins and makes all the difference

talon101 · Oct 2nd, 2006, 2:35 pm

i "have" the same problem. I bought a evo slave clynder and installed it, quick and easy. I bled the line and thought I was done, unfortunately on 3 separate occasions i grinded my 1st gear a bit (when downshifting) because the clutch didn't seem to engage.
I thought about bleeding it again but it hasn't happened since that 1 day. I don't know, also on the bleeder valve i have 2 metal washer and there seems to be fluid just under the base of the bottom washer. I don't know if that's a problem or not.
what do you guys think? should i bleed the line again? the bleed valve is tightened as much as the screw will allow.. any suggestions?

mbohn · May 27th, 2007, 1:45 pm

Well, I'm still fighting this. Bleed after every track day or 500 road miles. My dealer told me it was because of the hard track duty. Seriously, that's what the SM said!

Never mind that it does it after 500 road miles too.

Anyway, I searched herein and didn't find much except a bunch of people buying aftermarket slave pistons or slave cylinders. These are mainly folks that don't like the (high?) clutch lever effort. That's not my issue.

Has anybody considered excess temperatures at the slave causing brake fluid breakdown? If that evolved some vapor that didn't re-condense it would feel like air in the system and work its way up to the master and bleed just like air. I noticed the damn thing was way too hot to touch last week after a track session. I sure don't see any signs of fluid leaking anywhere. How can you get air in the system without having fluid come out somewhere?

I'm considering trying some Motul RBF 600 Dot 4 fluid. It is rated for nearly 600 deg F. Give it a good flush with that, then go abuse it at another track day !

Mac900 · May 27th, 2007, 2:56 pm

For all you folks that are continually having to bleed your systems: You have a leak somewhere. Period. It may be a slow leak and hard to find but you have a leak none the less. If by pumping the clutch lever a few times (without bleeding) the clutch action gets better then you will likely have a weak seal somewhere. Slave cylinders are the usual suspect for leaks and bad seals although masters can go too, but far more likely the slave. Clutch fluid should never reach the temperatures that brake fluid does because there is no huge build up of heat like rapid, continued, hard braking produces. Either that or there is lots of moisture in the fluid and it boils into a gas/vapor. A total flush may be in order but if the problem persists after that then it's a leak.