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  1. #1
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    Marta SL bleeding - what am I doing wrong?

    Previously, I started a thread asking about this, and after reading the responses, I discovered that I had the wrong bleed fitting. BTW, thank you to everyone who responded to help me figure that out. So, I got the correct fitting (thanks Lonnie @ Magura) and bled the brakes again. I was successful with the front brake, but I have done the rear twice now and it's not at all powerful like it should be. I'm seriously ready to give up on these unless I can figure it out.

    So, here is what I am doing (remember, rear only, because the front is fine now):

    1. mount bike in workstand so that it is somewhat vertical (brake line is about at a 45 degree angle this way - best I can do)

    2. unbolt caliper from frame, dangle it so that the brake line exits at the topmost portion of the caliper

    3. remove brake pads, retract pistons, and insert yellow transport device

    4. fill up bleed syringe (no air bubbles), remove bleed screw on caliper, and connect bleed syringe to caliper. I am not using the rubber o-ring on the bleed fitting, per someone's advice in the previous thread. Is this my problem? I tried using the o-ring when bleeding the front brake, but I kept getting fluid leaking out - it seems to seal better without the o-ring

    5. position master cylinder horizontally and remove cover and rubber membrane

    6. push fluid in bleed syringe through the system, taking up excess fluid from master cylinder with the other syringe as needed. I tap the caliper and brake line several times throughout to dislodge any air bubbles. But I'm not getting air bubbles at the master cylinder at this stage, which is surprising

    7. when the bleed syringe is empty (I am careful not to push air into the caliper), I start to get confused. Per the November 2003 directions on Mike T's Cult page FAQs, I am supposed to cycle the brake lever 20 times, keeping the master cylinder full at all times. However, it doesn't say what to do with the bleed syringe while I'm cycling the lever. I am gently manually drawing fluid into the bleed syringe as I cycle the lever, because I can't see any reason to cycle the lever otherwise. Am I doing the right thing? If not, what am I supposed to be doing while cycling the lever?

    8. once I have cycled the lever 20 times and filled the bleed syringe back up, I top off the master cylinder, replace the rubber membrane and cover, hold down the cover, and push fluid back into the system from the bleed syringe, taking care not to push any air into it. I stop when fluid starts leaking out the tiny hole atop the master cylinder cover. I then screw the master cylinder cover back down

    9. I replace the brake pads and put the caliper loosely onto the rotor and push fluid back into the system from the bleed syringe until I feel resistance

    10. I remove the caliper from the rotor, remove the brake pads, undo the bleed fitting, top off the bleed fitting hole with fluid, and replace the bleed screw

    11. I replace the brake pads and remount the caliper

    At this point, the system is theoretically properly bled. At first, the lever cycles all the way to the grip several times, which I assume is normal. However, the rear brake has no power, and the lever pulls back way too far (almost to the grip). No matter how many times I cycle the lever at this point, it doesn't get any better, and a quick test ride reveals that I have virtually no stopping power still.

    I get the feeling that I'm doing something wrong at (my) step 7. If so, can someone please explain in gory detail what I should be doing as I cycle the lever? For example, as I pull the lever back towards the grip, what should I be doing? Then, when I release the lever away from the grip, what should I be doing? Something different? I've been doing my own maintenance for years, and this is really driving me crazy. I don't want to have to rely on a shop to do something so simple, but if I can't figure it out, I'm just going to abandon the brakes for something else - I'm tired of my buddy telling me "you should have gone with Hayes."

    Sorry for the similar thread to before, but I'm at my wit's end, and I've missed too many nice riding days as a result.

  2. #2
    Bodhisattva
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    My only suggestion...

    I agree that Step 7 may be where air is getting in.

    Don't pull back on the syringe. Fluid will move through the system and up into the syringe when you cycle the lever. I suspect that you may be drawing air into the system when you manually pull back.
    I bleed both ways 3 times just to be sure. 3 times from the syringe and 3 times via lever cycling.
    Otherwise I'm out of ideas. Everything else is hunky-dory.
    Life....the original terminal illness

  3. #3
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    Thanks Squeaky! When you are cycling the lever, does your bleed syringe take in a significant amount of fluid on its own (without you manually working the syringe)? My syringes have a lot of stiction, so they don't slide very smoothly - it's always a jerky movement (I'm always splashing the master cylinder as a result), so that's why I didn't think that just cycling the brake lever was enough to push fluid into the bleed syringe by itself. I ask because you say that you do each three times, so your bleed syringe must be filling back up at the lever-cycling stage, correct? If so, that makes perfect sense, and I'll try it. Just want to confirm first, so that I can get this right once and for all.

  4. #4
    Bodhisattva
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    You got it.

    I fill up a 30cc syringe to start and just keep cycling the fluid back & forth.
    You may want to get a new syringe if the one you have is sticky. Try a good pharmacy or medical supply shop. If you have a friend who is an EMT or nurse then ask them to bring a few home from the office.

    I also use a long tube on my bleed syringe and velcro it vertically to my workstand so the air always stays up & the oil stays down.
    Life....the original terminal illness

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