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  • Occasional hard brake pedal

    After startup, I normally have a very hard brake pedal when driving a few metres then it goes ok after about 1 minute. Occasionally during driving I get that same feeling, very hard brake pedal and almost no assistance when braking, what could the problem be in this case? Perhaps I need to re-bleed the brakes?

    Think the accumulator is working fine as after startup then the pressure builds fine. Also I do have two rear daff ABS sensors (I think two at least!) would that have anything to do with it? Cheers
    1996 S2 ABY Silver

  • #2
    Originally posted by rynaqui View Post
    After startup, I normally have a very hard brake pedal when driving a few metres then it goes ok after about 1 minute. Occasionally during driving I get that same feeling, very hard brake pedal and almost no assistance when braking, what could the problem be in this case? Perhaps I need to re-bleed the brakes?

    Think the accumulator is working fine as after startup then the pressure builds fine. Also I do have two rear daff ABS sensors (I think two at least!) would that have anything to do with it? Cheers
    I had that when my servo went Bad
    RS 2 580HP

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    • #3
      I have been fearing this actually..

      Are there any more suggestions before I take the plunge on a new brake servo? My accumulator is new (only 1 year old).

      Can't really get this car finished can I
      1996 S2 ABY Silver

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      • #4
        It is endless Ryan. Mine is now all sorted and then my temp gauge starts reading a bit low. Now my brakes seem to be short of assistance for a mile or so after startup before feeling fine. Assume that might be a weak bomb but like you say, these cars are never perfect.

        Good luck with it.

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        • #5
          Correct me if wrong but isn't that the brake bomb. From what i understand it keeps pressure in, so your brakes will be efficant when you first drive off as the servo takes a few seconds. But this should also throw a light on with the issue ...... Or have I got it wrong. Sorry if I have got it wrong.

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          • #6
            You refer to the accumulator Jim. Ryanaqui make sure the wires to the pressure switch are actually connected.
            my bmob failed after a year the check valve stuck open causing the car to dump pas fluid

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            • #7
              Originally posted by Monkeymagic View Post
              You refer to the accumulator Jim. Ryanaqui make sure the wires to the pressure switch are actually connected.
              my bmob failed after a year the check valve stuck open causing the car to dump pas fluid
              They are connected and I never get the light, I used to get the light before I replaced the brake bomb so I am sure it is working fine. Also I got it when I replaced my hydraulic fluid with genuine Audi G00400.

              The problem started when I had the car sat for about four months, new rear brake kit and front calipers rebuilt, so all the fluid was drained and bled. Maybe I could try and bleed the system properly again..
              1996 S2 ABY Silver

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              • #8
                I'm a Doctor Jim, not a bomb disposal expert

                Originally posted by Human Joist View Post
                Correct me if wrong but isn't that the brake bomb?
                Originally posted by Monkeymagic View Post
                You refer to the accumulator Jim.
                RS2'd 93 UrS4 5 spd sedan
                94 UrS4 V8 6 spd manual avant

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                • #9
                  Does the pedal pulse when it goes hard?
                  Cheers'en, AndyC
                  1994 ABY Coupe - Projekt Alpinweiss

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                  • #10
                    Anybody else notice the difference in consistency of the rather gloopy G002000 OE fluid version it's replacement G004000 ?

                    They are both green but the new stuff feels desperately thin in comparison. Sorry for slightly OT.
                    Paul Nugent
                    Webmaster http://S2central.net
                    Administrator http://S2forum.com

                    1994 S2 Coupe ABY - aka Project Lazarus
                    2001 A6 allroad 2.5TDi - family tank
                    2003 S4 Avant 4.2 V8 - daily burble

                    Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

                    There are only 10 kinds of people that understand binary - those that do, and those that don't

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                    • #11
                      Just go vacuum Ryan.

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                      • #12
                        Check the pas pump.

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                        • #13
                          Bad servo
                          Panthero Coupé quattro 20vt
                          Indigo ABY coupé
                          Imola B6 S4 Avant

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                          • #14
                            I have a few second hand hydraulic servo's if required... £45 + post
                            Audi Nut!!!

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                            • #15
                              Just an update on the situation.

                              The brake pedal is now taking a good 3 minutes or so to free up. After stopping at a petrol station and chatting with some friends then starting up again, the pedal is also hard and took a while to free up.

                              What do you guys think? I was pointing towards brake bomb but the light isn't coming on and I get a good 40 pumps from the pedal when turned off before it goes hard.
                              1996 S2 ABY Silver

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