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  • caliper seal replacement

    Has anyone got a good procedure or know of a step by step guide for the replacement of the twin pot caliper seals? Thanks
    1986 Coupe q - 2281cc 3B, chargecooler, 2.75" exh & downpipe, ported head, water injection, CGR box, modified MD357 turbo, 440cc injectors, high power coil.
    2004 A4 2.5TDi convertible, re-mapped to 180bhp
    2011 A5 sportback 3TDi-Backbox delete, remap

  • #2
    are any pistons seized or anything? Or all free moving?
    Panthero Coupé quattro 20vt
    Indigo ABY coupé
    Imola B6 S4 Avant

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    • #3
      Heres a guide my mate Si did for some S14 4pots
      Different caliper but the process is the same - can't remember if the twin pots use circlips to retain the dust seals or not
      For some reason hotlinking doesn't work with these pics

      First of all the brakes will need cleaning up - mine initially looked like they did in the picture below:



      Attack them with a wire brush, remember you don't have to be careful not to nick the seals, as you'll be replacing them anyways, but be wary of catching the sides of the pistons with them. It's worth spending a fair bit of time doing this, as you need a good base to apply paint to. Get any small areas with a wire brush, then clean them up with white spirit. They should come up pretty well:



      Next step is to remove the old seals.
      To do this, place a small flat bladed screwdriver under the metal circlips than run over the seals, and lever them off. Watch your eyes at this step, they have a tendency to fly off! After removing the circlip, remove the seal with a screwdriver/pliers. Doesn't matter if you wreck it, as you really should rebuild with new seals anyways, so just grab them and pull, they should pop right off.



      This should leave you with something a little like below. work your way around all the pistons and remove all of the dust seals.



      Then the pistons will all need removing. Luckily, the pistons have a handy lip to use to get them out. Place a broad flat bladed screwdriver under the lip, and gently lever them out:



      This is the bit that took me the longest - a seized piston will often be a total mofo to remove - if this is the case, pull the piston out as much as you can, and then soak it in WD40. Then push it back in, soak it again, and lever it back out. repeat this a few times and it should eventually ease out. The best way to so the final part is to lever it out with a broad screwdriver, and a rest to put it on to act as a fulcrum as close to the piston as possible, so you can get maximum leverage.


      Next step is to clean up all of the pistons that came out - the best way to clean the piston itself is with some CLEAN brake fluid and a bit of rag - give them a good polish.
      Stubborn marks can sometimes be removed with some metal polish, but ensure that you remove all traces of it afterwards by cleaning it off with brake fluid.
      Remember, the top(lip) of the piston does not have to be spotless, but the sides do - any pistons with nicks/scores will need to be replaced, or they will let crap in and you will find yourself overhauling the brakes again in 6 months time. Hopefully the piston should clean up pretty well like the one below:



      Not like this one :



      Which, unsurprisingly, was from the seized pot. This piston was ditched in favour of a new one from www.brakeparts.co.uk

      The next part is to clean up the calliper itself - takes quite a while but it's worth doing well. Soak up all of the brake fluid, and clean out all of the pots with clean brake fluid. Ensure that they are as clean as you can possibly get them, and that the rag you are using is lint free, otherwise you'll leave lint all over the inside of the pots (not good!).

      Remove the old fluid seals with a pair of needle nosed pliers and a small flat bladed screwdriver - again, don't worry about damaging the seals, as they are going to be replaced, but be very careful not to mark the pots.

      Clean inside the seal lip with some clean brake fluid.

      See next post further down ------>
      Last edited by Error404; 8 January 2008, 17:41.
      Panthero Coupé quattro 20vt
      Indigo ABY coupé
      Imola B6 S4 Avant

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      • #4
        I'm rebuilding a pair of twin pots i've got sitting around pretty soon, so i'll take some pics and revise this guide to suit our calipers
        Panthero Coupé quattro 20vt
        Indigo ABY coupé
        Imola B6 S4 Avant

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        • #5
          overhaul

          Thats great, thanks.
          My twin pots are on the bench cleaned up ready but think I need to attach to car again to get the gentle pressure required to push them to there fully forward position (none are seized, just split seals). Cannot see any circlips on the seals and wondering how they attach to the caliper body?
          Couldn't open the pics up as it keeps asking for a login name and password!
          1986 Coupe q - 2281cc 3B, chargecooler, 2.75" exh & downpipe, ported head, water injection, CGR box, modified MD357 turbo, 440cc injectors, high power coil.
          2004 A4 2.5TDi convertible, re-mapped to 180bhp
          2011 A5 sportback 3TDi-Backbox delete, remap

          Comment


          • #6
            continuation......

            Now it's time to install new seals - using a rubber compatible high temperature grease (ask at your local motor factors), pack the seal cavities, and grease the fluid seals.



            Then install the seal into the cavity, ensuring it's properly seated.



            Repeat this for all of the pots, and then clean off any excess grease from the pots.



            Time to put them all back together...
            Ensure the pots are clean, and then put the calliper on one side, and fill up the pot with fresh brake fluid.
            Lubricate the outside of the piston with clean brake fluid, and gently ease it into the pot until the bottom of the lip is about 5mm from the calliper (not like in the photo below, i know that's not 5mm - it was a 'work in progress' )



            Repeat this with all of the pots - the best order to do this in is to start with the furthest piston from the fluid inlet and work your way back towards it, so the fluid doesn't all run out! watch out for fluid spurting out of the inlet as well...
            Bung the inlet with a bit of rag to prevent any fluid leaking out in the final step.

            Install the new dust seals in the pistons - they are a tightish fit over the top of the piston, but should seat nicely in the recess in the piston - ensure they are seated correctly (if they are not, try rotating them, and they should pop into place).
            Don't pull them too much though, as you may stretch and deform them, and they won't seal as well.

            Repeat this for all pistons:



            Finally, push all of the pistons home, so that the seals are level with the calliper, and install the circlips - these should sit snugly at the bottom of the seal - make sure they are properly seated or they may pop off. the best way to do this is to pull them apart slightly when you pop them over the top, and then pull them apart slightly when they are on and push them home, they should sit nicely on the bottom of the seal.



            Give them a lick of paint (the eagle eyed amongst you will notice that i did a coat half way through - this was just because i was waiting for a new piston)
            I wiped the callipers over with some white spirit first (being careful to not get it on the seals) just to remove any brake fluid that may have been spilt during the re-furb process.

            That's it! stick 'em on, flush and bleed the system (be aware that for the first few bleeds you'll probably get a fair amount of gunk flushed out from the grease used for assembly) and enjoy sticky free motoring!



            Can't remember off hand, but pretty sure the dust seal seats in a channel around the top of the pot
            Panthero Coupé quattro 20vt
            Indigo ABY coupé
            Imola B6 S4 Avant

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