FOR THE DO-IT-YOURSELF DUCATI OWNER |
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REPLACING / BLEEDING A DUCATI CLUTCH SLAVE CYLINDER |
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$140 |
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8, 9, 12, and 14mm Wrenches, 4mm Allen Wrench , Clear Tubing, Container, Lots of Towels, Rubber Mallet, Brake Fluid (DOT 4 or 5.1, but NOT 5) |
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The stock clutch slave cylinders on Ducatis are by no means known for their reliability or ease of pull. Thankfully, one of the few aftermarket parts readily available for a Ducati is the clutch slave cylinder. Two big names in the industry are Yoyodyne (sp?) and Evoluzione. After researching both and asking for opinions, I purchased the Evoluzione unit. |
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Ducati FINALLY arrived. But, I found out I needed both- one for the cylinder, and one to be fitted to the master cylinder for a better bleed (the master cylinder doesn't have the banjo bolt/bleeder screw combo). So, it worked out OK. |
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The Evoluzione unit is very nice. It's all billet aluminum, has three o-ring seals, and is backed by a ten year leak-free warranty. It was also significantly cheaper than the Yoyodyne, but received just as many favorable reviews. Plus I got a free banjo bolt. I'll take this space to plug Evoluzione Cyclesports- I had very good luck with them. The customer service was excellent, I received my order in two days, and the prices were good. Back to the slave cylinder. The installation was well-outlined in the instructions included, but I'll go ahead and skim over it in the following section. The first step in installing it is to cover the entire bike with rags. Brake fluid is extremely corrosive to finished surfaces. If you get any fluid on the paint (or anything else for that matter), immediately wash the area with soap and water. It only takes seconds to leave a permanent mark! |
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-DISCLAIMER- all of this assumes that you have a Ducati with the master cylinder/reservoir/lever in one piece, not the remote reservoir system. However, the rest of the process is very similar, so read on. You don't need to worry about working quickly to avoid getting air in the system- the second it sucks any amount of air you are in trouble, so just take your time. First (with bike covered) unscrew the banjo bolt holding the brake line at the master cylinder. Next, screw the bleeder banjo bolt in place of the plain banjo bolt, being sure to use the supplied crush washers. Do not overtighten, simply snug it up tight. Leave the bleeder fitting screwed in until later. |
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Now remove the two bolts holding the sprocket cover on. Next, unscrew the three bolts holding the old slave cylinder in place. Pull the master cylinder and accordian seal off of the clutch actuation rod. You can let the slave cylinder hang there, just be sure not to pump the clutch lever. |
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Next, unscrew the bleeder banjo bolt from the slave cylinder and pull the line off. Put the new crush washer on the new slave cylinder, then the clutch line, then the crush washer, then finally the bleeder banjo bolt. Again, do not overtighten (i.e. wrench it hard. It only needs to be tight enough not to vibrate loose). |
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All right, now you have the system closed off, but there is air in it. The very first step is to do something called 'reverse bleeding'. This is done with the slave cylinder hanging there. With the lid on the master cylinder (it doesn't HAVE to be on, it just prevents a stream of fluid from shooting ten feet in the air) you hold the slave cylinder in your hands, with the outside facing up. Then take your finger and push the piston inside as far into the slave cylinder as you can. A bunch of bubbles and fluid should come out into the master cylinder reservoir. You will need to then pump up the handle (slowly, with the reservoir covered to prevent a jet of fluid) a bunch of times to get fluid back down into the slave cylinder. BE VERY CAREFUL WHEN DOING THIS. If you pump too much (it takes a LOT of pumping when there is still air in the system) the piston could shoot out of the slave cylinder and you will have to start all over again. So, while pumping the handle, check that the piston isn't about to reach the end of the slave cylinder. The more you pump and push, the less air wil be in the system and the further the piston will travel with each pump. By the time you pump it four or five times and you can feel the piston travel pretty far and there are no air bubbles coming into the master cylinder reservoir (only fluid) you should be ready for a regular bleed. |
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From this point on, you need to monitor the fluid level. Make sure the bars are level, and the reservoir is full. As you bleed, fluid will be used up and you need to keep adding it. If it gets too low, air will enter the system. |
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First for the top. Put a small clear hose around the bleeder screw nipple, and put the end in a cup or something similar. Put the end wrench on the bleeder screw. Pump the handle several times, and while slightly applying pressure, unscrew the bleeder screw from the bleeder banjo bolt you just installed, and continue through the stroke |
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of the handle. At the end or near the end of the stroke, tighten the bleeder screw and release the handle. DO NOT RELEASE THE HANDLE UNTIL BLEEDER SCREW IS TIGHT! The only time the bleeder screw should be open is when you are pulling on the handle, and slowly. Do not pump the handle when the screw is open, because every time the handle is released it sucks fluid (and the air in the fluid) back inside. You must repeat this until you see no air bubbles coming out with the fluid. |
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UPDATE: An alternate method that seemed to work well was pulling in the clutch lever, then holding it and at the same time realeasing the bleeder screw. The springs in the clutch pack will force the piston back in it's bore, but since the screw is open, the fluid will take the path of least resistance and essentially bleed for you. Once the fluid stops flowing, tighten the screw, then pull in the handle and hold it again, then realease the bleeder screw, etc. With this method I was able to get a little better bleed than before, so you may want to try it out. |
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You'll notice that I didn't say to install the slave cylinder before bleeding. That's because interspersed with the bleeding, I would throw in the occasional reverse bleed from before. This isn't absolutely necessary, and it requires more dexterity to assure that the piston doesn't shoot out of the slave cylinder. I prefer to do this so that I know there is no air being trapped. You can now switch to the bottom fitting and repeat the entire process again. All of the above steps are applied to the bleeder screw on the slave cylinder. You can bleed the bottom screw with the slave off the bike, because most of the pressure will be directed out of the bleeder screw. Just be extra careful when pumping the handle that the piston doesn't shoot out. After you have bled the top and bottom, you need to tap the slave cylinder and fluid line with a mallet to dislodge any trapped air bubbles. |
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Now comes the fun part- doing it over again. Simply bleed the top and bottom bleeder screws again to make sure there is NO air. After that, you can install the old slave cylinder. Clean off the clutch rod, and apply some high temp grease. Be sure to read the instructions of whatever slave cylinder you are installing and get all the required parts in there (seals and stuff). Put some Loc-Tite on the bolts and simply snug them up. Then install the sprocket cover. |
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Now you're done. Take it for a test ride. If it doesn't work properly (i.e. no neutral finding at stops, no gear shifting at stops, hard shifting, etc.), then the most likely cause is still air in the system. Try bleeding again. If that doesn't work, here are some more suggestions: |
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Bleed it again. Yes, I am repeating myself because it takes a LOT of bleeding time for all air to exit. When I bled mine, I waited a week and bled it again, only to find an air bubble at the top and bottom. Same thing when I bled it two weeks later. Air bubbles will lodge in the lines and then surface later. |
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Or, maybe your clutch lever needs to be adjusted. There is a little screw on the side of the handle that actuates the piston inside. To adjust it, the slave cylinder needs to come off. Once it's off, remove the master cylinder reservoir cover. Using the reverse bleeding technique, push the piston in the slave cylinder and notice that fluid comes out. Now screw the screw clockwise about a 1/4 turn. Push on the piston again. If fluid still comes into the reservoir, screw the screw in again, and so on until you can't push the piston in with your fingers (i.e. no fluid can travel back into the reservoir with you pushing on the piston). Next, back it out 1/2 turn. Push on the piston again to make sure fluid travels back into the reservoir, and you're set. What happens if you screw the screw all the way in, but can still push fluid back in (and can't get neutral when stopped)? That's what happened to me, and some people suggested that I get an adjustable clutch lever from another model Ducati. I haven't done that yet, but I am sure it will work. |
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I have also heard of putting shims inside the slave cylinder piston to increase the travel of the rod, but am very hesitant about doing that. |
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This page is in no way associated with Ducati.com, nor is it an entity of Ducati Motor Holding, S.p.A. All content, information, and views expressed herein are those of myself and do not reflect those of Ducati or its affiliates. The "DUCATI" logo and "Circle D" are registered trademarks of Ducati Motor Holding, S.p.A., all other content on this website is copyright 2002, Monster Man Productions. If you would like to link to my page, feel free to do so. If you would like to use the pictures or text on your own page, please e-mail me, or at least give me credit and install a link to this web page. |