Clutch pump/fade
 

I am having problems with the clutch on my 748! When i had it serviced had new clutch plates, and fluid, which then resulted in the clutch fading like rubbish brakes might on a track day when they get hot. On motorway runs when the clutch was spinning fast (over 8k revs) the biting point would come right back to the bars....

I bled the fluid, got some air out - this improved it and i thought it was fixed. BUT, it came back when i did a track day and every session after about 5/10mins the clutch would come back to the bars without doing much (scary going down the gears into a corner! Engine braking comes a bit sooner than expected ;-).

So far any air has been bled out of the fluid twice now, so it's not that anymore - anyone have any ideas what it might be now????

Also makes a BIG vibration when i give it big revs to pull away.... (not sure if related)

Thanks for any advice!

Clutch slave seals are the most likely suspect, could be you clutch slave cylinder on it's way out. Look for fluid weeping from it.

If the reservoir needs topping up regularly there's a leak somewhere.

Other than the slave cylinder, check all the banjo joints and hoses for signs of leaks, it could also be your master cylinder but that's less likely than the slave

I had a similar problem with the 996, clutch would be all right until the bike got hot especially in traffic,then it would sart to bite even when the lever was back to the bars. Last week I stripped down the clutch,gave it a dusting down,also removed the slave cylinder and cleaned around the push rod seals,removed the push rod, re-assembled the clutch plates and refitted every thing. Bled the master and slave cylinders took her out for a spin and low and behold the clutch worked a treat .
If the clutch is all right until the bikes gets hot then its got to be some thing to do with the fluid,old fluid can absorb moisture this can boil if close to a heat source, causing a failure to pressurise the system properly. The juddering at take of sounds like dusty plates . 4D

Also check the pushrod bearing at the clutch
 

I had very similar problems recently.

I've replaced the clutch slave piston (which was leaking slightly), greased the pushrod, replaced the pushrod gaiter, renewed the fluid and bled the system (twice). The pushrod at the pressure plate end had obviously been binding somehow as the hole in the slave cylinder piston had been machined by the rod spinning in the hole.

All working fine now :D

BTW ~ I bought a really good gizmo bleeder thingy on eBay - all it consists of is 3 or 4 syringes and some tubing, but for £4, its halved the time taken to do the job as it enabled me to reverse bleed the lines by sucking fluid through rather than pushing air out

I'll find the link and paste it up.....<edit> that link is for a 749 kit, but it may well be the same, if not, check his other items.

http://cgi.ebay.co.uk/DUCATI-749-DAR...cm dZViewItem

BRB

Push rod not spinning in its bearing is the most likley cause. When you think about it, if you are blasting down the road at 8000rpm then the clutch should be generating no heat at all plus the air flow at speed will keep it cool as well.

good thing you solved it zhed. On mine, i completely flushed the system and cleaned the slave cylinder. I also greased everything and filled in some fresh Dot 5.1 fluid. It's ok, but only if i bleed it from time to time... every 300-400 miles. Otherwise the lever release point get's closer to the bar.

I still have to replace the pushrod (i belive it's bent cause i had a serious fall on the clutch side)

thing is it goes back to normal in just about 3 or 4 minutes after i've pulled in - and it isn;t effected by heat from tick over or anything - only when the plates are spinning really fast as in revving high.

I took the slave cylinder off and with the engine running in neutral i could stop the pushrod moving by holding it with my fingers so the bearing seems ok, and there doesn;t appear to be any fluid leaks or anything it's all bone dry.

Maybe as Shazam says there's water vapour in the system somewhere? I'll give that a try....

HI Jody
Was you on the Yellow 748 at cadwell that nipped out at dinner?? Intermediate group??

ive had exactly the same. no problem with hard road riding but on first trackday at oulton park with the 748 lost the ckutch after about 4 laps, changed the rubber hose to a braided one and changed the fluid. second trackday at oulton lost the clutch after about 4 laps! noticed that when it was hot the slave cylinder was weeping. bought a norton products slave cylinder off ebay used the same brand fluid and next time out at oulton the clutch was fine all day. mine was the early type slave not the uprated one but sounds very similar to me.
hope this helps,
mark.