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Thread: Brake bleed DIY with DSC

  1. #1
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    Brake bleed DIY with DSC

    I was all set to bleed my own brakes on my 2002 roady until I read the Bentley manual which cautioned against doing this as a DIY. From my searches in this forum it seems the issue is with an electronic module associated with the DSC that somehow traps fluid behind it unless activated. Some of the posts suggest that you bleed the brakes, then drive in gravel or grass to activate the DSC, and then re-bleed.

    What are the risks if you don't do the breed, activate DSC, rebleed sequence?

    I'm concerned that driving hard enough on gravel or grass to activate the DSC could kick up debris that could lead to paint chips or other body damage which would eliminate the cost offset of the DIY approach in the first place.

  2. #2
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    Bleed the brakes...drive.. bleed them again. If your doing regular brake bleeds you should not have to do any tricks to activate the ABS pump.

  3. #3
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    I bled the brakes every few months when the 02 was on the track twice a month. Never had an issue. But I never sucked/pushed air into the system either. I used the old fashioned two person method.
    Dan "PbFut" Rose

  4. #4
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    Quote Originally Posted by SunzOut View Post
    Bleed the brakes...drive.. bleed them again. If your doing regular brake bleeds you should not have to do any tricks to activate the ABS pump.
    Quote Originally Posted by PbFut View Post
    I bled the brakes every few months when the 02 was on the track twice a month. Never had an issue. But I never sucked/pushed air into the system either. I used the old fashioned two person method.
    +1

    Key is to NOT allow air to enter the brake system. Monitor your brake fluid levels closely when bleeding the calipers.

    -2019 F31 Individual M-sport Touring
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  5. #5
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    If you're worried, then bleed w/ the key in the on position. BMW mechanic once told me to do that. I think when the key is switched on, the ABS pump cycles or something.

    I had all my calipers removed, new brake lines installed, and even new brake master cylinder + clutch master cylinder too. I was worried about air in the ABS unit. I just used a pressure bleeder, and switched the key to on position each time I went to bleed a caliper... and now the brakes feel perfect. Nice and firm pedal too. I can pretty much lock the brakes (abs will kick in though) If I get on them too.

    Good luck!~

  6. #6
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    ^ nice, i'm in the middle of doing exactly that and was concerned.
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  7. #7
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    I bleed often and have switched fluid multiple times this year with my S54/DSC car. I have finally found a method that works with out having a GT1 to cycle the DSC pump:

    • Use the old fashioned two person method
    • Before you have the person in the car press the brakes, have them start the car
    • Crack the bleeder
    • The DSC light should go solid
    • Close the bleeder
    • Have the person in the car release the brake pedal and then turn the car off to reset DSC
    • Repeat as necessary


    Doing it this way causes the DSC pump to cycle as you crack the bleeder. DSC will see too much pressure loss and error out. That's why you must restart the car to reset things--hitting the DSC button won't cycle it.

    Enjoy the nice firm brake pedal.

    -bj

  8. #8
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    There is also a relay you can jumper to cycle the ABS pump during a bleed.

    IMHO, this isn't something to worry about. There isn't that much fluid in the ABS pump anyway and if you do a bleed once a year, it will work itself out. Particularly for street driving. If you track the car, the ABS system will likely cycle multiple times per session and the DSC system should be off. But then you are changing fluid VERY often anyway so the fluid should be relatively fresh. If you run good fluid and still need to do an ABS/DSC activation to prevent fluid boiling, something else is wrong. Either technique or no cooling or something....

    This really isn't something to worry about, just bleed the brakes and drive the car.

    The hydraulics are a dead end system and the fluid in the ABS pump doesn't make it's way to the caliper unless there is a leak or you are doing a bleed. But then you should bleed until there is new fluid anyway.

    Now, if you get air in the system, that's another story.....
    Last edited by osborni; 01-06-2011 at 09:46 AM.
    - Ian
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  9. #9
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    Quote Originally Posted by osborni View Post
    There is also a relay you can jumper to cycle the ABS pump during a bleed.
    That doesn't work with DSC, only ASC. You have to have a GT1 to cycle DSC unless you use my method above. Using my AutoEnginuity I can cycle the DSC pump on later E46 M3s with the MK60 DSC system, but on cars like the Z3M that have the MK20 system you can't.

    Quote Originally Posted by osborni View Post
    IMHO, this isn't something to worry about.
    The way DSC works is much different than ASC. DSC actually has it's own feed off of the master cylinder and an inline feed with each caliper independently.

    You're right, it doesn't make much of a difference on a street car, but I have never felt like the pedal get truly firm unless I cycle DSC.

    -bj

  10. #10
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    Thanks to all. Great info. It is a pleasure to learn from your wisdom. I appreciate the the spirit in which these more "basic" questions are answered.

  11. #11
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    The DSC system I'm familiar with is off the e39. IIRC, abs=dsc there. But that was 6-7 years ago.

    Surprised you still have DSC on a track car.... It just wears out brake pads faster if it's on.
    Last edited by osborni; 01-06-2011 at 11:14 AM.
    - Ian
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  12. #12
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    Quote Originally Posted by cincychuck View Post
    Thanks to all. Great info. It is a pleasure to learn from your wisdom. I appreciate the the spirit in which these more "basic" questions are answered.
    The AutoLogics system that I use has an ABS bleed function, so if you're up for the drive to Toledo, we can do it. Just want to make sure that my lift is open before heading up.

  13. #13
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    Quote Originally Posted by osborni View Post
    The DSC system I'm familiar with is off the e39. IIRC, abs=dsc there. But that was 6-7 years ago.

    Surprised you still have DSC on a track car.... It just wears out brake pads faster if it's on.
    Just a case of deactivating it for track use, right?
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  14. #14
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    Quote Originally Posted by osborni View Post
    Surprised you still have DSC on a track car.... It just wears out brake pads faster if it's on.

    I leave it on my track car because ABS is integrated in to DSC. In the dry I always run with it off (ABS is always active).

    I usually consider myself a pretty good rain racer: neither of my LeMons cars nor my 944 race car have ABS or traction control. I usually get around great in the rain.

    For grins I did some testing at Watkins Glen in the rain and snow last April. I found that in the M Coupe I was slightly faster with DSC on than off. Part of that may have been that it was my first time at the Glen and I was willing to push it a little more with DSC on.

    -bj

  15. #15
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    I've done the two person method twice in the past two years on my 97' 1.9, no problems yet. Good info in this thread tho, I didnt know about any of this..
    Always in progress!

  16. #16
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    hey everyone,

    i rebuilt (incl. new pistons) and painted my calipers. i did the bleeding procedure three times (key in the off position). now i have the problem, that the pedal does not feel as tight as it felt before, i can force the pedal to the ground, but just with the engine started. on top of that, i just need to tap the pedal and the car immediately starts to brake. usually there is a bit room left, isn't it? do you think this might have to do with the interchanged brake pads (right brake pads installed on the left caliper and so on)?

    hope you can help me.

    edit: i forgot to mention i own a '98 s50b32 m-coupé without dsc.

    best regards,
    Phil
    Last edited by RST Driver; 01-10-2011 at 02:17 PM.

  17. #17
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    Quote Originally Posted by loftygoals View Post
    I leave it on my track car because ABS is integrated in to DSC. In the dry I always run with it off (ABS is always active).

    I usually consider myself a pretty good rain racer: neither of my LeMons cars nor my 944 race car have ABS or traction control. I usually get around great in the rain.

    For grins I did some testing at Watkins Glen in the rain and snow last April. I found that in the M Coupe I was slightly faster with DSC on than off. Part of that may have been that it was my first time at the Glen and I was willing to push it a little more with DSC on.

    -bj
    I can see in the rain that it might be faster. But in the dry, DSC on my old e39 never allowed enough slip to get power down. Might be different calibrations though. There aren't enough people that are willing to give up information on ABS/DSC calibration that I'm aware of.
    - Ian
    2000 M Coupe, stripped and DE prepped

    46mm wheel bearing socket for rent - $30 deposit + $10 fee. PM for details.

  18. #18
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    Quote Originally Posted by osborni View Post
    ..., DSC on my old e39 never allowed enough slip to get power down.
    Totally agree in the dry. DSC interferes too much with big slip angles, also.

    -bj

  19. #19
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    Don't know about US spec cars and I don't know if this is general or for the E46 M3 only, but when you press the DSC switch once, it's only half of. Supposedly you can press the switch and keep it pressed. The light should then blink and then it should be totally off.

    I don't have DSC so I can't check.
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  20. #20
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    Quote Originally Posted by MParallel View Post
    Don't know about US spec cars and I don't know if this is general or for the E46 M3 only, but when you press the DSC switch once, it's only half of. Supposedly you can press the switch and keep it pressed. The light should then blink and then it should be totally off.

    I don't have DSC so I can't check.
    On the S54 Z3M, it is either on or off. If you press and hold you can enable dyno mode, though. Once you enter dyno mode, you can't turn DSC back on. You must turn the car off and back on to enable it.

    -bj

  21. #21
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    Quote Originally Posted by loftygoals View Post
    On the S54 Z3M, it is either on or off. If you press and hold you can enable dyno mode, though. Once you enter dyno mode, you can't turn DSC back on. You must turn the car off and back on to enable it.

    -bj
    Dyno mode? Interesting. What exactly does this do? I would say turn it off, but you can also do that with a single press.
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  22. #22
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    Quote Originally Posted by MParallel View Post
    Dyno mode? Interesting. What exactly does this do? I would say turn it off, but you can also do that with a single press.
    If you put a S54 car on the dyno, the DSC system keeps the car from reving to redline. On pre-2003.5 S54 E46s and MZ3s, you can defeat this with the press and hold on the DSC button.

    There are quite a few threads about this over in the E46 M3 section.

    -bj

  23. #23
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    Quote Originally Posted by RST Driver View Post
    hey everyone,

    i rebuilt (incl. new pistons) and painted my calipers. i did the bleeding procedure three times (key in the off position). now i have the problem, that the pedal does not feel as tight as it felt before, i can force the pedal to the ground, but just with the engine started. on top of that, i just need to tap the pedal and the car immediately starts to brake. usually there is a bit room left, isn't it? do you think this might have to do with the interchanged brake pads (right brake pads accidentally installed on the left caliper and so on)?

    hope you can help me.

    edit: i forgot to mention i own a '98 s50b32 m-coupé without dsc.
    no one?
    shall i try bleeding with the ignition turned on?

    best regards,
    Phil

  24. #24
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    Bumpin' this. Has anyone else had success with these aforementioned methods?

  25. #25
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    Quote Originally Posted by loftygoals View Post
    I bleed often and have switched fluid multiple times this year with my S54/DSC car. I have finally found a method that works with out having a GT1 to cycle the DSC pump:

    • Use the old fashioned two person method
    • Before you have the person in the car press the brakes, have them start the car
    • Crack the bleeder
    • The DSC light should go solid
    • Close the bleeder
    • Have the person in the car release the brake pedal and then turn the car off to reset DSC
    • Repeat as necessary


    Doing it this way causes the DSC pump to cycle as you crack the bleeder. DSC will see too much pressure loss and error out. That's why you must restart the car to reset things--hitting the DSC button won't cycle it.

    Enjoy the nice firm brake pedal.

    -bj
    Yes, the above method works
    Quote Originally Posted by Eazy-E46 View Post
    Bumpin' this. Has anyone else had success with these aforementioned methods?

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