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Thread: Found my clutch's dirty butt

  1. #1
    apriliaforum expert wavz's Avatar
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    Found my clutch's dirty butt

    This is just some photos I took of my last clutch fluid swap using my new brake bleeder and the RFI method (reverse fluid injection).

    I'm not a mechanic and this is the first time I've even touched the clutch slave so the pictures are more for us non-technical type so we know where the black poo comes from.

    The system I am using is the V-12 Brake Bleeder from Phoenix Systems http://www.brakebleeder.com/product.php?pid=2

    It has just about every adapter you can think of for connecting to your brake system.



    I had started off doing the front brakes. There is a handy elbow adapter that fits perfectly onto the nipple.



    Old habits die hard so while I was squeezing the grip with one hand I would use the other hand to hold onto the elbow and "open" the line by using the elbow to turn the nipple. I'd maintain pressure by squeezing the grip on the V-12, open the line using the elbow, continue to squeeze until fluid starting showing up in the MC, then I would close the connection using the elbow, then let off the grip on the V-12 to reduce the risk of any reverse flow or air getting in. Probably not necessary but it's just habit



    The tool has this handy magnetic clip to help keep the bottle from falling over while you work. Here I have it attached to my fork leg.



    Now the clutch slave. I begin by cleaning out the fluid in the clutch's MC reservoir. Yes it was black and here is the towel after I cleaned out the soot left in the reservoir.



    I connected to the clutch slave and began pumping clean fluid up from the nipple to the MC. The fluid kept turning black so went ahead and took the clutch slave off. Make SURE your clutch's MC stays full of fluid before you take the clutch slave off. The reason will become clear in a moment.



    Notice the lub on the clutch slave already. Not sure if this was from Aprilia or from one of the service techs but I was surprised to see so much lub on it. Notice the round drum that the lub is sitting on, that your piston for the clutch and in the center is the infamous o-ring. You can actually force this drum in and out by compressing it. When you do this, take a look at the clutch's MC and you'll see the fluid go up and down with the movement of this piston.



    Notice the black soot on the post as well.



    Finally, here is the culprit. It's no wonder the fluid turns black with all this gunk in there. I believe the proper way to clean this would be to take the slave apart but I chose not to do this. I intend on replacing the clutch slave with an Evo in the future.



    I am hoping this is the right silicon lub for the o-ring. It's basically found in the plumbing section as professional plumber use this on the black o-ring found in plumbing to increase the life of the o-ring. The product says it's good up to 400 degree Fahrenheit, I hope so.



    I really like the fact that it was clear.



    Once I applied the silicon grease to the post and the o-ring I then reattached the clutch slave. The torque settings are 12 nM or 8.8 pounds. Once the clutch slave was back on I began the bleeding process again using RFI. I filled the clutch's MC using reverse flow from the nipple up to the MC about 4 times before achieving clean fluid. Here is the end result, we'll see how long it stays this way!




    The beauty in all this is that it hardly took any time to do by using the V-12. I never even had to touch the clutch or brake lever. When I was done it was as if I had never done anything. I had a full brake and the clutch worked perfectly. No spongy feel before the brake firmed up or anything like that. With the use of the V-12 I won't dread making this a routine part of my maintenance.

    Hopefully this has taken the mystery out of where the black clutch fluid comes from.

    Last edited by wavz; 06-05-2013 at 03:43 PM.

  2. #2
    apriliaforum Member
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    thanks a bunch!!! My clutch lever just seemed to get spongy and now it seems that the clutch disengages (or engages) after farther down in the lever pull. My fluid is soooo black. I didn't know what color it was supposed to be since I've never changed clutch fluid before. I figured I'd try to bleed it first and change the fluid to see if that helped. I will follow these steps exactly and buy that bleeder device. Great post


    Thanks again

    JC

  3. #3
    apriliaforum expert kzmille's Avatar
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    Wavs, I applaud your self reliance. The Pheonix unit is a good tool. I have been using one for several years.

    The black mess in the small seal on the back side of the slave cylinder piston has no connection whatsoever to the fluid in the hydraulic system. The O-ring mentioned so often on these forums is on the outer diameter of the piston and cannot be seen unless the piston is forced further out. All the little seal on the back side does is keep road grunge from getting into the area between the piston and push rod.

  4. #4
    apriliaforum expert wavz's Avatar
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    Quote Originally Posted by kzmille View Post
    Wavs, I applaud your self reliance. The Pheonix unit is a good tool. I have been using one for several years.

    The black mess in the small seal on the back side of the slave cylinder piston has no connection whatsoever to the fluid in the hydraulic system. The O-ring mentioned so often on these forums is on the outer diameter of the piston and cannot be seen unless the piston is forced further out. All the little seal on the back side does is keep road grunge from getting into the area between the piston and push rod.
    Arhgg, so I was one step away from solving this for good? After 500 miles the fluid is already starting to turn black. I was hesitant about taking the drum off because I wasn't sure what was going to happen (imagine springs flying every which way).

    So when the drum comes off is there anything intricate to putting it back together? I'll add photos to this thread of this step once I do it again.

    Thanks kzmille

  5. #5
    apriliaforum expert ohiomike's Avatar
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    I use a childs medicine dropper ( basically like a small turkey baster)and pull most of the fluid out of the resivoir and poor in new stuff about every 500 miles. Takes all of 2 minutes to do with NO bleeding.. Its clear most of the time...

  6. #6
    apriliaforum expert kzmille's Avatar
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    wavz,

    There is really not much to it.

    Take a look here:

    http://www.apriliaforum.com/forums/s...d.php?t=153541

  7. #7
    apriliaforum expert dougan's Avatar
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    I wanna poor some mud on your bike..... I could eat breakfast off that chain.

    great write-up wavs.
    Project Svensk: Husq 510
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  8. #8
    apriliaforum expert wavz's Avatar
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    Thanks kzmille!

    If you don't mind I've included your post to this thread to keep the content useful.

    Thanks dougan! I love gooold! I keep the bike's chain clean to match the bling that I wear round my neck during outings. The ladies love my gold pinky ring, 24k gold log chain and 8 inch gold clock that I wear.


    credit to kzmille

    Quote Originally Posted by kzmille View Post
    The pictures below are typical of what you find in the aprilia slave and clearly indicate (to me anyway) a lack of adequate lubrication. Two years ago I assembled my original 01 Mille slave cylinder with the original seal using silicone O-ring lubricant. I filled the system with DOT 5 silicone bake fluid and the fluid in the reservoir is still crystal clear. There have been no leaks, no dramas, no problems of any kind. It is due for a fluid change. I will pull the slave apart and show you what I find.

    By the way, I do not recommend using Dot 5 silicone fluid in Brembo brakes. I used it in my Brembo equipped BMW for over twenty years. It does not damage the seals or any other part of the system but it does cause problems with pad retraction due to the design of the brake caliper O-rings. The clutch system does not use the square section O-rings used in brake calipers so there are no problems of this sort when using silicone in the clutch system.
    Attached Images Attached Images   

  9. #9
    apriliaforum expert wavz's Avatar
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    Continued....

    Quote Originally Posted by kzmille View Post
    When I first disassembled my slave cylinder two years ago it looked much like the pictures above. Black rubber residue smeared all over the piston OD and cylinder ID. I've just taken it apart and this is what I found. No smeared rubber anywhere. There is a very small amount of rubber particles in the bottom of the cylinder that are hard to see in the pictures. This is my original slave cylinder and seal. Just short of 19,000 miles. The bike is used for Sunday sport rides and track days. Very little highway droning and I always use the clutch to shift.
    Attached Images Attached Images    

  10. #10
    apriliaforum expert wavz's Avatar
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    Ok, so I dug into this project again tonight and wanted to add some things. Sorry, I did not take photos of the additional steps but kzmille's photos are pretty self explanatory.

    Be SURE to turn the handlebars both directions completely, you'd be surprised how much air gets caught in the MC. I'm using Motul 5.1 for the clutch fluid and Motul Dot 4 for the front and rear brake.

    A side benefit to doing this is the reduction in clutch pull. The clutch is super easy to pull in now and probably equates to a 30-40% reduction in effort.


  11. #11
    apriliaforum expert kzmille's Avatar
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    Yes, optimizing the position of the MC is key to easy and thorough bleeding.

    Good work guy.

  12. #12
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    Quote Originally Posted by jamminjc12 View Post
    thanks a bunch!!! My clutch lever just seemed to get spongy and now it seems that the clutch disengages (or engages) after farther down in the lever pull. My fluid is soooo black. I didn't know what color it was supposed to be since I've never changed clutch fluid before. I figured I'd try to bleed it first and change the fluid to see if that helped. I will follow these steps exactly and buy that bleeder device. Great post


    Thanks again

    JC
    Hey JamminI sure as old as this post is you have all this more than under control but i just replaced my clutch slave seal yesterday and there were a few things worth noting.

    Even if your fluid isn't turning black, if your clutch is getting spongy and losing pull length before disengagement bleeding the system will likely only mask the symptom. and will probably get spongy again and with shorter times between as the seal gets more wear. Once seal wear start a fluid starts seeping out i gather grit and grime around it which even further speeds up the deterioration of the seal.

    Here are a few lil tips i thought i would add for members future use.
    - Once you have removed the 3 slave cyl. bolts, pull the slave cylinder out and clean with brake cleaner and a small brass brush (before splitting it)

    - Spray the clutch pushrod a few times and if needed clean lightly with a scouring pad to remove build up.

    - Sometimes the slave cylinder halves are stuck together because of all the gunk but put two large crescent wrenches (one on each half) and lightly twist and they should start moving enough so that you can separate them.

    - Now slide the piston out of its bore and set aside. Clean the cylinder bore really well especially down towards the bottom where there is a grove all the way around (stuff likes to build up in there) And clean the to slave halves inside and out because you have to assume anything you leave on the outside will end up on the inside before you done.

    - Pull the spring off of the piston and set aside and use a pick set and small needle nose to remove the old outer seal. Now clean the piston and make sure there is no crud in the seal groove.

    - I like to use a light film of seal safe lube on the inside and outside of the seal but like i said a light film. Now work the seal onto the piston and replace spring to in position.

    - I also use a film of the same grease around the lip of the bore. Now slide your piston in the bore just be careful that you don't get the seal caught up.

    The rest is just the opposite of removal and then the bleeding that already explained here.

    Like i said i was just replacing the one yesterday and then saw this thread and thought i would share how i go through the matter.

  13. #13
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    I too saw my fluid go back to black very quickly after a short distance - is this normal?
    The clutch functions well - but dirty looking juice is a bit disconcerting.

  14. #14
    apriliaforum Junkie UKWes's Avatar
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    It's normal, my 06 has been like it for the 3 years I've had it.
    Not done the seal story as above, so don't know if this is a real cure, but refreshing the fluid sees it go black again within a short time.
    The rear brake reservoir also shows black fluid....but the front never does
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  15. #15
    apriliaforum prov-nov grizzlymann's Avatar
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    Anyone happen to have some backups of the pictures?

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