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NS Front Brake Not Working - ABS Issue?

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  • NS Front Brake Not Working - ABS Issue?

    Today I decided to look at the NS brake calliper as the car is swerving to the right when braking. One the capper was removed from its mounting I depressed the brake pedal to force the pistons out but they never moved. Next I undid the bleed nipple and engaged the assistance of Mrs Brown with some down/up brake pedal operation. Surprisingly nothing canes out so I then removed the calliper to check the flexi hose and still nothing came out despite inserting a wire and checking for blockages. Last of all I undid the brake pipe from the outlet on the ABS unit and that gave the same result. Anyone had anything similar, maybe it’s the brake bias valve? The only other thing I’ve noticed is the brake pedal is quite hard but after a while it has freed up and the calliper starts working again but goes back to normal after leaving for a week.
    Attached Files
    Steve

    1990 RR 20V
    1982 SWB UR - RS2 Engine


  • #2
    Alright steve it could be the solenoid in the abs unit as this happened to a friends s2 coupe aby

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    • #3
      After a good period of driving it will operate as normal like it did on the journey back from Torquay to Doncaster. I think I will start taking a look at the unit this weekend.

      Can someone please tell me how to purge the ABS?
      Last edited by steverrquattro; 24 February 2023, 12:25.
      Steve

      1990 RR 20V
      1982 SWB UR - RS2 Engine

      Comment


      • #4
        That is odd. As Mac say's could be the solenoid in the ABS unit.

        I was going to suggest a collapsed fleixi pipe but you've ruled this out by the sounds of it...
        1989 B3 2.0 3A 80 quattro... Budget 1.8T Project.
        1992 C4 100 2.8 Avant quattro... Mobile Sitting Room.
        1995 RS2... MTM K26/7 380 BHP Conversion.
        1990 Corrado G60... Breaking For Parts.

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        • #5
          I have a spare abs unit here if you are stuck.
          Nothelle S2 Avant
          Black Ur project
          Ocianic Ur project gone
          S2 Coupe project gone
          Urs6 plus project gone

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          • #6
            First of all I gave the block on top of the ABS unit several taps with the mallet as I’d read this on another thread. I then tried pressure bleeding and when I opened the bleed nipple nothing came out but it did dribble out from around the threads. The bleed nipple was then removed and found to be blocked. When installed back in I was finally able to bleed the brake.

            However when road tested the calliper on the NS was still not engaging. So it was removed once more from the carrier and the brake pedal applied. This time the piston came out but just one whereas I expected them both to come out? It was then pushed back in and the pedal applied again and the other one came out. Pushed it back in and then road tested and now working.

            All I will say at the moment is that the fluid looks dirty and I’ll do another test drive tomorrow to see if it’s still working.
            Attached Files
            Steve

            1990 RR 20V
            1982 SWB UR - RS2 Engine

            Comment


            • #7
              That fluid looks well passed it's best. I would also look at a rebuild kit for the callipers. My guess rust has got on the piston and that's what is causing it to stick. I would also look a rebuilding the rear at the same time.

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              • #8
                Originally posted by B5NUT View Post
                That fluid looks well passed it's best. I would also look at a rebuild kit for the callipers. My guess rust has got on the piston and that's what is causing it to stick. I would also look a rebuilding the rear at the same time.
                It’s got the best service history of any car I’ve ever seen but that brake fluid is rank. Where do you get your rebuild kits from?
                Steve

                1990 RR 20V
                1982 SWB UR - RS2 Engine

                Comment


                • #9
                  Sometimes you have to take service history with a pinch of salt! One of my neighbours always has his car serviced every year, but refuses to have any fluids changed other than oil, his car is on an 07 plate he has had the car since new. He's thinking of selling it and claiming it's got full service history

                  Think I got my kits from autodoc, but you can get them from ebay as well

                  Front
                  D41719C AUTOFREN SEINSA Repair Kit, brake caliper Front Axle ➤ AUTODOC
                  Rear
                  D4845C AUTOFREN SEINSA Repair Kit, brake caliper Rear Axle ➤ AUTODOC

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                  • #10
                    Agree. Those brakes need an overhaul.
                    Nothelle S2 Avant
                    Black Ur project
                    Ocianic Ur project gone
                    S2 Coupe project gone
                    Urs6 plus project gone

                    Comment


                    • #11
                      Originally posted by B5NUT View Post
                      Sometimes you have to take service history with a pinch of salt! One of my neighbours always has his car serviced every year, but refuses to have any fluids changed other than oil, his car is on an 07 plate he has had the car since new. He's thinking of selling it and claiming it's got full service history

                      Think I got my kits from autodoc, but you can get them from ebay as well

                      Front
                      D41719C AUTOFREN SEINSA Repair Kit, brake caliper Front Axle ➤ AUTODOC
                      Rear
                      D4845C AUTOFREN SEINSA Repair Kit, brake caliper Rear Axle ➤ AUTODOC
                      Absolutely brilliant that and very much appreciated. Also thanks to Tractor Dave for the offer of the spare ABS unit.

                      Rebuilding the brakes is a job I've never done as it's always been a case of not having the time resulting in an emergency exchange at GSF. However I fancy doing these myself and save a bit of cash as well.
                      Steve

                      1990 RR 20V
                      1982 SWB UR - RS2 Engine

                      Comment


                      • #12
                        Not too difficult and very rewarding. Send me a pm if you get stuck. I've done quite a few now. I would recommend getting a kit with new pistons.
                        Nothelle S2 Avant
                        Black Ur project
                        Ocianic Ur project gone
                        S2 Coupe project gone
                        Urs6 plus project gone

                        Comment


                        • #13
                          Originally posted by steverrquattro View Post

                          Absolutely brilliant that and very much appreciated. Also thanks to Tractor Dave for the offer of the spare ABS unit.

                          Rebuilding the brakes is a job I've never done as it's always been a case of not having the time resulting in an emergency exchange at GSF. However I fancy doing these myself and save a bit of cash as well.
                          We did the front calipers on my lad's Skoda recently, we were fitting new pads and pistons were quite hard to push in. I looked under the dust seals and could see rust.
                          Got pistons and seals from Autodoc, not expensive and the job went well and he now has excellent brakes.

                          S2 Coupe 3B Project


                          Ur quattro restoration

                          S2 Avant

                          Boost is the new rock and roll!
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                          • #14
                            AndyP has rebuilt quite a few sets of brakes for people

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                            • #15
                              Be careful ordering from Autodoc, their parts cross referencing system is crap and you'll inevitably get the wrong kit! I get all mine from Biggred.

                              https://www.biggred.co.uk/audi-coupe...er-repair-kits


                              sigpic
                              1991 Audi S2 3B - 2.5 Stroker engine
                              1997 A6 2.5TDi quattro avant - C4
                              1976 RD250E / 350LC cafe racer

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