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Thread: Getting air out of ABS unit - brake bleeding

  1. #1
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    Getting air out of ABS unit - brake bleeding

    They say the Smart need be connected up to a Star machine to get all of the air out. ABS pump has to run and some normally closed valves probably need be open. ICM's WinStar regrettably does not yet have the capability to do this.

    Above photo shows ABS circuit on a Honda Civic. I assume the Smart is very similar.

    I think it will somehow be possible, without a Star machine, but with some clever tricks to fool the ABS unit such that ABS pump will run and internal valves be opened at will:

    1. Create sine waves using signal generators.
    2. Send signal generator output through an amplifier.
    3. Excite each wheel speed sensor using electromagnetic transducers (ET) driven by signal generator.
    4. ABS unit can be activated by reducing frequency on one wheel at the time. ABS pump will run, the internal normally close valve will open and the corresponding internal ABS circuit can be bled.


    Any thoughts?

    and

    Could anyone with access to a Star machine kindly advise how bleeding the ABS unit is carried out?
    Last edited by tolsen; 28-06-2010 at 07:37 AM.
    Drives a Smart Cdi - 65 to 85 MPG

  2. #2
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    Basically what happens is the Star machine runs the ABS pump and while that is happening you need to press the brake pedal while someone else releases the bleed nipple on one wheel at a time then shuts off the nipple when you release the pedal as with normal brake bleeding. The procedure is carried out the exact same way as usual just that the Star is running the ABS whilst you do it.
    It is sometimes possible to do it by taking the car out onto a gravel road and braking hard causing the ABS to cut in then bleeding the brakes.

    Regards
    DJP
    Its Nice To Be Important..... But Its More Important To Be Nice!!!

    Proud to be a Lincolnshire Smartie


    PureSmart - Smart Car Servicing Specialists
    Servicing, Diagnostics, Magna Carta Remaps, Parts & Accessories, Genuine Ultraseal


  3. #3
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    Quote Originally Posted by DJ-Power View Post
    Basically what happens is the Star machine runs the ABS pump and while that is happening you need to press the brake pedal while someone else releases the bleed nipple on one wheel at a time then shuts off the nipple when you release the pedal as with normal brake bleeding. The procedure is carried out the exact same way as usual just that the Star is running the ABS whilst you do it.
    It is sometimes possible to do it by taking the car out onto a gravel road and braking hard causing the ABS to cut in then bleeding the brakes.

    Regards
    DJP
    Thanks for explaining DJP.
    I assume all valves go to open position. Is there any time limit on for how long the ABS pump can run? Can it overheat?
    Cheers,
    TK
    Drives a Smart Cdi - 65 to 85 MPG

  4. #4
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    Yes correct. The Star recommends that the ABS is run for a maximum time of 60 seconds.

    Regards
    DJP
    Its Nice To Be Important..... But Its More Important To Be Nice!!!

    Proud to be a Lincolnshire Smartie


    PureSmart - Smart Car Servicing Specialists
    Servicing, Diagnostics, Magna Carta Remaps, Parts & Accessories, Genuine Ultraseal


  5. #5
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    Not sure this relevant to the aim of this particular thread but it is connected to brake bleeding.
    I heard that the Pela can be used, but lacking experience of vacuum bleeding on non ABS cars even, I am wondering if there is any use for it on a smart.
    Once more, I want to achieve something on my smart by mechanical methods rather than by using computers!

  6. #6
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    Quote Originally Posted by DJ-Power View Post
    Yes correct. The Star recommends that the ABS is run for a maximum time of 60 seconds.

    Regards
    DJP
    Thanks for that DJP.

    Is there any vibration in the pedal when you push it to bleed whilst ABS pump is run by the diagonistics?
    Drives a Smart Cdi - 65 to 85 MPG

  7. #7
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    Now finally working actively on my ABS bleed contraption. May get it operational within a couple of days. Extremely simple design. Using a dead cheap dual channel signal generator (PM me if you want one), a bunch of resistors and four SPDT centre off switches to run ABS pump. Parts cost about 10 pounds but overall cost much less, more like minus 40 pounds. Have spent a lot less on ale whilst designing and making my prototype.
    Drives a Smart Cdi - 65 to 85 MPG

  8. #8
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    Any chance of a photo sounds very interesting

  9. #9
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    Quote Originally Posted by tolsen View Post
    Using a dead cheap dual channel signal generator (PM me if you want one),
    Hi TK. The above I'm intersted in (for a project I'm researching). Have you a link to the item in question?
    In your opening post, you mention using an amplifier. What type of amp do you have in mind?

  10. #10
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    Quote Originally Posted by pinger View Post
    Hi TK. The above I'm intersted in (for a project I'm researching). Have you a link to the item in question?
    In your opening post, you mention using an amplifier. What type of amp do you have in mind?
    A German chap named Christian Zeitnitz has made an amazing sound card oscilloscope program. He has made the software available freely on the internet for private use. The oscilloscope software has integral frequency analyser and signal generator.
    I don't need the amplifier as I am hard wiring the signal to the ABS unit at the connectors for each ABS sensor. Signal from an ABS wheel speed sensor is only 0.8 volts peak to peak. Max voltage from headphone jack on my PC is 0.3 volts RMS so OK.
    Drives a Smart Cdi - 65 to 85 MPG

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