More Clutch Problems on my 748...Help!

[thrustercat]

Hiya Chaps, not a good weekend…I fear that I have, yet again, more clutch problems. I have not owned my 1999 748bp for long and I seem to be having lots of problems in a short space of time. I’m kind of new to DSC and hope that someone can point me in the right direction.

I have noticed that the clutch lever action on my 748 seems to have a little extra play than it should. On looking at some of the comments posted by dukess999 clutch problem ‘Stephen’ mentioned that the slave cylinder could have seized… perhaps this could be my problem?! I know for a fact that the clutch is not slipping.

Even when I have the bike in 1st gear and the clutch lever pulled in (when stood still), I have noticed that I cannot move the bike back and forth in a ‘neutral’ gear state.

I had a 12k service at the end of July by TecMoto, primarily because I had the classic slipping clutch problem. The plates were replaced which solved the problem.

I would be grateful if someone can point me in the right direction, or perhaps help me to diagnose the problem further.

Much appreciated for any help you can provide.

:(

[Edited on 28-9-2003 by thrustercat]

[Edited on 6-10-2003 by thrustercat]

[Jon]

thrustercat. Remove the clutch cover and see how much the pressure plate moves when pulling in the clutch. See if by pumping the lever the plate moves any further. The reason I say this is that once when cleaning out my clutch I managed to let the fluid level drop. Don't ask me how because I've no idea, When came to use the clutch I could feel straight away that all was not well. The lever came all the way back to the bar without any real resistance. Once I bled the system it was fine.

[thrustercat]

thanks for the advice Jon, I shall bleed the clutch sometime this week, hopefully this will lead to an easy solution.

[thrustercat]

Right...bled clutch, which took all of 5 minutes. Has the assistance of another pair of hands and now all is working okay - fantastic stuff.

[thrustercat]

I have bled the clutch a number of times now, and each time I take it for its initial 5mile run the same symptoms occur - excess play in the clutch leaver, less resistance and generally feeling very spongy, until you can bring it to the handlebar with no resistance at all!

I have also noticed that the clutch fluid has turned black \ grey when bleeding?! I don't understand what is causing this - it’s as though the clutch fluid is burning up.

I used dot 5.1 synthetic clutch fluid (not sure if other have had issued using dot 5.1). I have now flushed it and am using dot 4. I have read articles where I have to keep on bleeding, over and over again until it is okay…sounds like an air block somewhere.

I am now getting fed up taking my 8mm spanner, bleeding pot and clutch fluid wherever I go!!

Advice appreciated.

[nelly]

sounds like the seal on the slave cylinder piston has gone.
It's pretty common. Check around the back of the slave cylinder and front sprocket for fluid.
Replacement isn't too difficult. You can use either a new Ducati one or an Evoluzione one. The Evo ones has better seals and cost about £3 more at £18.
I stock the Evo ones.
It's far less common but similar symptons can be had from thes eals in the master cylinder failing to.
The fluid will turn black........."they all do that".
I use 5.1 fluid with no problems, so you're OK there.

[antonye]

As Nelly says, the problem is probably a dodgy seal which will be causing air to leak into the system (giving you the recurring bleeding problem) and also causing your fluid to turn black.

I've seen Ashley's bike and I don't know if his clutch slave cylinder is a standard one - it has a star shaped pattern on it, with lots of points (almost like a bi-hex socket!) rather than having the Ducati circle/D shape on it... if that helps!

[nelly]

The cylinder with the star shaped cutout is standard Ducati. It's the later design to alleviate all of the early problems they had, like leaking piston seals :lol:

[Shazaam!]

If you have not already done so, you can make bleeding much easier if you replace the banjo bolt at the master cylinder line connection with a bleeder-type banjo bolt. The master cylinder area is where most of the air rises to, gets trapped, and cannot be bled out (easily) using the bleed nipple down by the slave unit.

http://home.san.rr.com/shazaam/BleederBolt.jpg

If an inspection doesn't reveal a fluid leak, there's another common problem that mimics having air in the clutch hydraulic system. The clutch pushrod is spinning because the bearing in the pressure plate is not moving freely. This causes the pushrod to move the clutch slave piston back into its bore slightly.

So, when you ride for awhile without using the clutch, when you try to use it, you have to pump the lever a little to first move the cylinder back into position, after which it works normally. Low-pull aftermarket slave units accentuate this problem because a full lever stroke moves the slave cylinder piston a shorter distance than it does the stock unit.

You usually just need to lubricate or replace the pushrod bearing on pressure plate to cure the problem.

[antonye]

Nice post Shazaam!

I also know that Ashley's just had a new clutch in his bike (like sub 1,000 miles ago) so I doubt it would be the bearing that is failing...

[thrustercat]

Thank you to all for the advice. I am now on the case and will let you know how I get on. :)

[thrustercat]

Cannot get replacement Slave Cylinder to fit my 1999 748!

I purchased a Ducati Replacement Slave Cylinder from Ron Parkinson, which included a Piston and a Cap. I immediately noticed that the replacement was smaller than the original SC (Slave Cylinder), and after a long conversation with RP (Ron Parkinson) expressing a concern with the actual size compared to the original, the chaps assured me that this was the right one. So...I handed over a nifty and they handed me the replacement SC.

Next job...fix the SC to the 748. Fitting was simple, bleed the clutch, remove bleed nipple and banjo bolt...and off with the three bolts, take out the old and replace with the new.

I lubricated the piston placed in the cap and slid the unit over the pushrod. I noticed that it was difficult to push the RP SC onto the Pushrod. I had to give it some elbow grease to get the thing on. When I looked down the eye of the SC where the banjo bolt usually goes I could see the piston and pushrod was very close to the start of the SC cap. After scratching my head, and the assurance of RP I got on with the job.

Anyway, I continued to bolt up the 3 screws, bled the clutch through. Got some clutch resistance after 20 minutes of bleeding...then all of a sudden the clutch lever went completely solid, until I could not bring the clutch lever back to the handlebar. I consulted the Book of Lies (Haynes Manual) which did not really help.

At this point I was sure that the replacement SC had to be the wrong part. It was either the Pushrod was too long (I would say by 1 cm) or the replacement SC was too small.

Armed with more cash, I took a trip down to TecMoto (nr A12/M25) to buy their "Oversized Clutch Slave Cylinder". After another long conversation with my existing problem; they assured me that their SC would fit my 748.

I got home, fitted the thing and exactly the same symptoms occurred. Quite luckily most of my mates are petrol heads, and another was a DukeSPS owner. All were pretty much dumbfounded by the problem. All came to the decision that the SCs were too small or the Pushrod was too long (will post some pics tonight !). Took off the clutch cover, and released all the springs to ensure nothing was a miss. All looked okay, and the centre nut was done up securely. Put the springs and the clutch cover back on, and proceeding to put the original SC back on my bike. Bled the system through and all was okay - fact - I know that the original SC will not last long before I loose clutch resistance again.

In light of my issues, I would really appreciate if you boys can give me some advice.

Question: Is my pushrod too long? Can anyone give me a default size of a Pushrod. I would like to compare it to mine. Has anyone had any success fitting the TecMoto Oversized Slave Cylinder? Are my SCs to small?

Much appreciated.

[Edited on 6-10-2003 by thrustercat]

[nelly]

There has been a change in SC but whether or not the pushrod was changed I couldn't tell you for sure.
I have a 748E in at the moment with the new SC and the pushrod on that is 326mm long.
There are different length pushrods, but as I said, I couldn't tell you for sure if they are a result of the different SC's.
The slave cylinders I have had made seem to work OK whatever bike they've gone on so I don't know why the Tecmoto product should play up??
Is your pushrod OK. They have been known to snap, in isolated cases, around the undercuts where the two o-rings sit.
Only other thing I can suggest is to check the master cylinder is returning OK.
There is a small screw that adjusts the amount of free play on the lever.
There is a "trick" to screw this in to gain a little more cylinder movement, but if over adjusted prevents the cylinder returning properly. The cylinder then pumps up and prevents the pressure being released when the lever is let out.

[thrustercat]

Just been on phone with TecMoto, and they tell me that the standard size Pushrod for their Oversized SC is 325mm. Mine is around 330mm, and apparantly Duke Pushrods can go up to 335mm. Once I hack off 5mm it should be okay.

TecMoto told me to bring in my Pushrod next Sat and they will hack of 5mm which should then fit comfortably in the SC.

I also heard that the different Pushrod lengths were related to the range of SCs that are on the market.

[Edited on 6-10-2003 by thrustercat]

[Shazaam!]

It's interesting to note that Ducati slave cylinders are not interchangeable between the pre-2001 and 2001+ superbikes because the pushrod length is different.

When Ducati solved the slave cylinder leakage problem in 2001, they modified the slave cylinder on all bikes, except the SPS. That modification to the housing design required the use of a 10mm longer pushrod. Check out:

http://www.moto-one.com.au/performance/clutch_slave_cyl.html

So, you should have the shorter pushrod unless you installed the revised slave and pushrod. From antonye's above description of your Ducati slave unit it sounds like you had the updated Ducati slave cylinder installed so you'll also have the longer pushrod. If so, that's probably part of your problem.

At least one manufacturer now offers two models of aftermarket clutch slave replacement units. For example, Yoyodyne offers two versions:

Part No. D001 - Fits up to year 2000 with the shorter pushrod
Part No. D002 - Fits 2001 - and up with the longer pushrod

Tecmoto and evoluzione only offer one version on their website so it appears that some aftermarket units are expected to work well with the longer pushrod length.

My guess is that your (new) clutch pack height (check that it's not too short) combined with the longer pushrod is the source of the problem.

[Edited on 10-6-2003 by Shazaam!]

[Mark853]

Hi all,
if you have the star in the middle of the slave cylinder it is the latest ducati one, it also uses the longer pushrod.

If you fit an aftermarket slave cylinder you will have to purchase the shorter earlier push rod. They are about £14 and i would do this rarther than cut your original one.

Interesting to know that the modified Ducati one failed just the same as the earlier ones though!

All the best


Mark

[thrustercat]

Thanks to all for your input chaps - much appreciated. I shall let you know how I get on next week. :)

[Road Runner]

My 996 had its first MOT at Snells today and I asked about the colour of the clutch fluid as mine is very dark and they said its ok it will discolour very quickly but thats normal on Ducati's.

Mark :sing:

[rcgbob44]

Roadrunner, methinks you have just been told a load of crap! The fluid in my 998s remains clear and even the fluid in my Jota (which takes a lot of stick) is always clear!!!!!

[Shazaam!]

rcgbob44, Road Runner's experience is more common.

Perhaps the reason why your clutch fluid remains clear is either because you've changed it or Ducati finally is using a different fluid at the factory.

I've been following this topic with interest for a few years now and I've collected a lot of anecdotal information about this phenomena from discussions on the web. Here's a summary of reported observations and my own experience:

(1) The clutch fluid darkens on new bikes before leaving the showroom.

(2) Replacing the clutch hydraulic line has stopped the color change.

(3) Replacing the clutch slave cylinder has stopped the color change.

(4) Replacing the clutch master cylinder has stopped the color change.

(5) Honda claims their new clutch fluid will minimize fluid darkening on their bikes.

(6) The clutch, but not the brake, hydraulic fluid changes color.


Speculation on the source of the contamination includes:

(1) Particles shed from the rubber hydraulic line material.

(2) Particles worn from the slave cylinder seal material.

(3) Aluminum particles worn from the OEM slave cylinder bore material.

(4) Contamination of the fluid by debris flung from the chain.

One observation has been that if you change to one of the aftermarket slave cylinders that have a different seal material that either has no carbon black or is more abrasion resistant, then the fluid color shift stops, or at least slows significantly. Since these aftermarket units have a hard-anodized finish on the bore, it's been suggested this also helps to reduce seal abrasion and particle release. The aluminum stock unit piston bore isn't hardened, so it's been assumed that minute aluminum particles also contribute to the darkened color.

I believe that this is a red herring. In all cases, the common factor in minimizing or eliminating this problem has been to replace the Ducati OEM brake fluid that is installed at the factory. Whatever fluid (extra-virgin olive oil?) they're using, it darkens from some combination of moisture, heat and age, or more likely by just by chemically attacking the rubber lines and piston seals that releases their carbon black into the fluid. (Remember, when you change out a component you also end up changing a good portion of the fluid.)

I suspect that continuous heat plays a part in breaking down the synthetic rubber slave seal and hydraulic line material, since the slave cylinder (and adjacent line) is mounted directly to the engine casing. Brake hydraulic fluid that sees intermittent higher temperatures does not undergo this discoloration. However it's possible that Ducati uses a different fluid for the clutch and brakes.

One important clue is that Honda claims that their new improved clutch fluid is formulated to minimize the same color change in Hondas, suggesting that Honda has found that the problem is somehow accelerated by the hot hydraulic fluid chemically attacking certain materials rather than by seal wear alone. So they reformulated their fluid or changed vendors.

Another clue is that black hydraulic fluid has also been observed in automobiles. A chemical analysis by Detroit gurus determined that the color came from carbon black suspended in the fluid. It was leached out of piston seal material or the hydraulic line and into the fluid, turning it black.

Reliable reports from Ducati owners say that if you replace the clutch slave unit and/or the stock hydraulic line with aftermarket units the color change stops. This is not the real solution to this problem however. The common thread is that owners flush the fluid when they change these components. Several owners reported that the color change stopped after simply changing the fluid.

The bottom line is - ignore it. It doesn't hurt anything. If you can't live with black fluid, flush out the factory fluid. Change it every 18 months or so to remove moisture buildup (absorbed from the air) that will corrode any metal that it comes in contact with.


Anyone care to comment?

[thrustercat]

I orginally thought that the clutch fluid was burning up on my duke, as when I went to bleed the fluid looked as though it had somehow coagulated; dark grey(ish) black fluid. Apparantly I hear that all bikes do this; heat, pressure, etc.

It my case I had to change the fluid a number of times, and depending where I broke down will dictate the different types of clutch fluid that were available to me at the time. Could this not be the reason why the clutch fluid changes colour?

Out of interest, has anyone else experienced the same symptons if Dot 4 and Dot 5.1 are mixed. I am aware that mixing the different types is bad for the bike, but what is the real effect on mixing the two?

On another note, Ron Parkinsons only supply 335mm PushRods from Ducati?! TecMoto alledgedly sell all 3; 325mm, 330mm and 335mm. However, I expect that these are all aftermarket PushRods.

[antonye]

Ashley - see Shazaam!'s post here for an explanation about mixing fluids:

http://ducatisportingclub.com/control/boards/viewthread.php?tid=2740

[Shazaam!]

Just to clarify:

DOT 3 and DOT 4 fluids are compatible with DOT 5.1 - but are NOT compatible with silicone-based DOT 5. DOT 5 brake fluid is dyed purple to warn against accidental mixing.

The use of the 5.1 designation is really confusing.

5.1 is a lighter viscosity glycol-based fluid with that was developed for use in ABS systems that need to cycle on and off quickly. It really has no advantage over the DOT 4 fluid recommended by Ducati.