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  #11  
Old 29-Sep-2003, 11:39
thrustercat
 
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Thank you to all for the advice. I am now on the case and will let you know how I get on.
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  #12  
Old 06-Oct-2003, 13:09
thrustercat
 
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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]
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  #13  
Old 06-Oct-2003, 13:33
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nelly nelly is offline
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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.
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  #14  
Old 06-Oct-2003, 14:40
thrustercat
 
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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]
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  #15  
Old 06-Oct-2003, 19:08
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DSC Member Shazaam! Shazaam! is offline
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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/performan...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!]
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  #16  
Old 06-Oct-2003, 20:06
Mark853 Mark853 is offline
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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
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  #17  
Old 06-Oct-2003, 22:08
thrustercat
 
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Thanks to all for your input chaps - much appreciated. I shall let you know how I get on next week.
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  #18  
Old 06-Oct-2003, 23:18
Road Runner Road Runner is offline
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clutch fluid

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
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  #19  
Old 07-Oct-2003, 09:48
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rcgbob44 rcgbob44 is offline
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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!!!!!
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  #20  
Old 07-Oct-2003, 15:41
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Black Clutch Fluid

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?
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