Spongy brake pedal after rear caliper change.

Discussion in 'E90 Saloon / E92 Coupe / E93 Convertible M3 (2008-2013)' started by Kenneth, Jun 15, 2018.

  1. 15 Jun 2018 at 6:43 AM #1
    Kenneth

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    Hi can anyone offer some advice please.
    I’ve just changed the near side rear caliper on my friends E92.
    Job all went fine and lost minor fluid, bled that caliper on completion the old school way with him sat in the car pressing and holding the pedal down whilst I did the bleed nipple.
    Unfortunately there now seems to be a spongy section of travel on the pedal before it goes hard, if you pump the pedal it goes rock hard after 2 pumps.

    I’ve read sometimes with new pads this happens and they just bed in, can this be the case with a new caliper? Cant see what there is to bed in???
    Existing discs and pads used as these are only a few hundred mile old.

    Any advice on how to get rid of this spongy pedal?
     
  2. 15 Jun 2018 at 6:59 AM #2
    Dave818185

    Dave818185 Rocking a new hat

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    Did you only bleed the 1 calliper. Try bleeding them all. If that doesn’t work you need to plug it in to get the abs pump to cycle.
     
  3. 15 Jun 2018 at 8:34 AM #3
    TrojanHP

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    It’s likely that the pads wore in to how the old calliper sat, had this very recently with an E46 M. If you watch the caliper while someone presses the pedal you’ll often see it twist slightly, and this is the spongy feeling you get. It should go away/get better with miles, but could take quite a while depending on how bad it is.

    Simplest/quickest option is a new set of pads.
     
  4. 15 Jun 2018 at 11:32 AM #4
    Kenneth

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    Cheers chaps I’ll see how it goes and then recommend pads if it gets no better.

    How does cycling the abs work then? There is no way we introduced air.
     
  5. 15 Jun 2018 at 12:24 PM #5
    ccfj1

    ccfj1 Moderator

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    You have air in the system

    Smack the caliper while bleeding, that should shift the air bubbles.
     
  6. 15 Jun 2018 at 1:50 PM #6
    tmpchicken

    tmpchicken On the path

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    You said you used the two-man method, which is my personal favourite, but sometimes when you say 'up' or 'down' you can both get out of sync.

    If the guy in the car goes up when you open the nipple you can get air introduced. Just try bleeding all four legs again, starting with the nearest (front right) and ending with the furthest (rear left) from the master cylinder.

    I'm sure you did this already but my method is this:

    Shout 'down'. Only open the nipple when your colleague has applied pressure to the pedal. It should then sink to the floor and literally squirt fluid/air out of the nipple into your collector tubing. He then stays there with his foot on the floor whilst you close the nipple. You then shout 'up' and up he goes gently. You have to stop every few goes to re-fill the master cylinder.

    If you don't do track days then a litre of Pagid fluid from EuroCarpets is a fiver.

    I used the exact method above on the E92 M3 after I swapped out the ABS pump - thus losing all fluid and introducing a ton of air. This technique easily and reliably got all the air out and left me with a great pedal first time.
     
    Last edited: Jun 15, 2018
  7. 15 Jun 2018 at 4:31 PM #7
    Subzero269

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    Air in the system - 100%. You may think you got it all out but bleed it again and you will see tiny air bubbles coming out (been there a lot!).
     
  8. 16 Jun 2018 at 12:07 PM #8
    Kenneth

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    Thanks chaps. I’ll do it again, all 4 legs to be sure.
     

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