Clutch pump ?

[Tängri]

Hello!

For two or three days, the speeds have not passed so well... This evening, leaving my broadcasting studio in Paris, I found the clutch lever very very soft, and the speeds passed with very difficulty.
It seems to be the clutch pump. On the french website "Ducatannonces", they sell a clutch pump for 750 Paso (1989). My question is : is it the same than a 907 one's ?
Best regards

[ducinthebay]

If I am not mistaken, the slave cylinder on a 907 is the same as current Ducati motors. As always, bleed the system first, and check for leaks.

Cheers,

[Jaffa]

Hello there,

This sounds like a bleed problem to me. Loosing pressure in the line as a result of a fluid leak somewhere. This usually occurs at the slave cylinder (engine) end of the system.

When you squeeze the lever at the handle bars, fluid is forced into the line, causing a piston to push on the clutch rod which disengages the clutch plates. The piston has an o-ring on it to stop fluid leakage. This is protected by a rubber boot behind the slave cylinder. Sometimes, (well quite regularly actually) this rubber boot can become worn or dislodged from its usual position, allowing crud from the road and chain fling to enter, stuffing the seal around the o-ring.

The o-ring is fairly easy to replace, though bleeding the system can be a pain in the butt. (There a number of blogs here describing how to re-pressurise the clutch system)

Have a look before going to the expense of purchasing replacements.

Good luck.

[jcslocum]

I think you mean the clutch master cylinder.

I'm sure it will work fine.

[Laddie907]

check the fluid level in the reservoir.
if the reservoir is full it's unlikely you have air in the system or a hydraulic problem.
the system seems to bleed easily - mine does, anyway - just keep slowly pumping the lever.

the master cylinders seem to give few problems..so unless you've had a major seal failure at the slave cylinder (which seems to be a common problem) loss of clutch tension can be caused by a broken spring hub screw.
Over-tensioning the screws is easy - they're just tiny M5 screws.

the loss of a spring will lower the lever pressure a fair bit
so if the bleeding doesn't improve things the next thing to look at will be the clutch springs

[Tängri]

Thank you for your explanations, guys. I understood it's the slave cylinder, and I'll have a new one next week. It's impossible to find an o'ring only... The slave cylinder is not diifficult to change, I know. The fluid is gone in the carter and I think that it would be better to change the motor oil after that, because the fluid is very corrosive. I'll tell you how it has been.

[ducbertus]

The fluid has gone into the carter??
how do you know that for sure?
there is no direct connection between the slave cilinder and the casings.
the slave cylinder operates a pushrod system across the main drive shaft.
so leaking from the slave would cause oil spill around the front sprocket, I assume.

Ducbertus

[persempre907]

It seems to me very odd, too.
No matter, an oil change is always worth.
Ciao

[Tängri]

Hello!
Some news about my clutch (not really poetic but august news...)
The leak is actually in the clutch control's area...The mechanic sold me a new one : a very new one, because it fits only with the recent Ducati's... He didn't see that the 907'one has a hole in the middle to fit the clutch hose. May be it's hard to find a 907's clutch control (and piston, and so and so) -- I don't know. So I cleaned the original system, replaced the lip joint (thank you for your advice), purged it, and took my bike for a dream trip in the quite desertic streets of Paris (hum! not so desertic, because too much people have no money to escape for hollidays)...then I discovered that the end of the clutch hose had a leak ! And it seems to be close to the "banjo" connection. Two days after, there is no more fluid in the reservoir. I don't think that to purge and to change the clutch fluid three times in a week is an interesting hobby... And fluid is not good for my precious hands !
Four conclusions and two questions :
1 - The clutch pump is not guilty.
2 - The clutch control piston has a serious problem, because I found a big quantity of joint past in it... It seems not to be regular...
3 - The previous owner had some difficulties to find a clutch control system, or he was quite mean.
4 - An old Ducati is as exciting as a good novel, and you find every day a new subject of brain sport.
5 - According your great experience, has the problem one chance to be in the hose connection ?
6 - Is it possible to fit a new clutch control system, for instance by some junction of the purge valve and the clutch hose ?

Best regards

[englishstiv]

T mate

Hello

I have followed this thread with interest and I think I understand that the problem is that you are losing fluid where the lower bango bolt meets the small pump (housed in the rear left casing by the drive sprocket) that pushes an internal piston onto the clutch rod which in turn passes through the engine onto the clutch mechanism and releases the clutch..................Yes?

If this is the case then the part you require is the full pump body and is known in the UK as a "PISTON 748-996B" that kind of also tells you that it's a fairly standard part and interchangeable with a few other bikes. UK STOCK CODE 19590023B they cost around £20.00 so probably 20 Euros for you.

Also just make sure that you have copper washers on the bango bolts incase it has been damaged there aswell, although for what it costs I would stick a new hose on.

Your problem sounds like one I had and would drain the clutch fluid in less than half hour riding or overnight in the garage and was solved by changing the piston it takes about twenty minutes.

[riascns]

Looking at other forums, and from personnal experience last year, it seems that there are several issues with the slave cylinder and seal.

If the slave cylinder is not corroded and marked, then a seal from a 916 should solve the problem.

If the cylinder is corroded, then for the 907 you need to buy a new cylinder, plus a special connecting bolt as Ducati have redesigned the cylinder and changed the positions of the hydraulic hose and bleed nipple on the newer design.

From what I have read, one should consider this seal a consumable item, and therefore it should be changed every year and the cylinder cleaned and reassembled.

All in, I think I payed about £45 from Ducati Manchester for the official parts.

[Tängri]

Hello!

About our dear clutch system, something new : yes, it's possible to fit a new clutch control and piston. I did it ! Fortunatly, because the previous system is not available at the factory... The new one is better than the older, we know that, even it's not a general rule...
The only thing that makes me anxious (we must be anxious for our Ducatis!) is the hose: don't know if a quarter of a round, to fit the clutch hose on the same hole than the bleeder, is so good for it... Hope. All we need is hope.
The result is very pleasant : the gears pass so well, so smoothly, just like a Ducati !

Read you later.