[Ducati] Gear change/clutch action

[Martin Philp]

Some thoughts from my experience with bleeding the clutch and brake systems.
 
I've just changed the clutch fluid on my Bimota DB4ie (900SSie engine) to which I've fitted an STM clutch slave cylinder (due to the larger piston there is more travel at the clutch lever so you have to adjust the span to suit). The clutch was working afterwards but the lever had some free play and it was difficult to get into neutral. As has been mentioned however much you bleed from the nipple on the slave cylinder you'll never get the air out from the banjo at the master cylinder, any air bubbles will rise up the pipe and collect there. Since first reading about this I always remove the clip-on  after changing the fluid and angle it so that any air will rise up the master cylinder, and with the pipe to the reservoir at the highest point. Then gently pump the lever, I always get a few bubbles appear in the reservoir. After doing this the lever free play is gone and the gearchange is better. I normally repeat after a couple of rides for peace of mind! This method works so well on both clutch and brake that I'm surprised it isn't given as standard practice in manuals. As suggested you could fit a bleed nipple at the master cylinders to get the air out, haven't got around to that yet.
 
Take care if you try adjusting the screw in the lever, I once tried reducing the lever travel on my Paso rear brake by adjusting the master piston travel but overdid it with dire results. The piston wasn't returning far enough to uncover the hole connecting the cylinder to the reservoir, at a track day as the system heated up and expanded (don't know whether it was the fluid or disk, etc) there was nowhere for the fluid to go so the pads couldn't retract properly and were rubbing on the disk, which in turn heated everything up still more, until eventually the brake locked itself on, fortunately on the slowing down lap. I had to wait for it to cool off then get lifted off the circuit - very embarassing! The pad material had come away from the back plates and 'welded' itself to the disk!
 
Martin Philp
2000 Bimota DB4ie
1989 Ducati Paso 750   
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