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Couple of questions on replacing caliper seals/pistons

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  • Couple of questions on replacing caliper seals/pistons

    Last year my offside rear caliper started sticking so I had it refurbed by CPC when it was serviced. I'm now getting the same thing on the front nearside caliper and am thinking of doing it myself - probably both of them while I'm at it as it does seem to have got to the age/mileage when these things are starting to happen

    I have had a read of the refurb thread in the Knowledge Base and have a couple of questions:

    Looking at www.brakeparts.co.uk there are 3 things listed:

    Caliper Service Kit (BCK6003) @ £15.48
    Caliper seal kit (BCS6003) @ £12.04
    Caliper piston (BCP6019) @ £18.46

    What's in the caliper service kit and am I right in thinking that it includes the seal or do I need the seal kit as well? I'm assuming that replacing the piston at the same time is the sensible thing to do (Phil did)

    In the Knowledge Base thread the writer said that they had used an air line to blast the old piston out. What the best way of doing this if you don't have an air line? Any particular tools recommended for this and the rest of the job?
    www.tracking-shot.com

  • #2
    I got my service parts from there. The service kit includes the seals, rubber bushes and nipple covers. The seal kit is just the seals.

    A new piston is not always a necessity, it depends on the condition of the old one. When I refurbished some front calipers I cleaned up the top of the piston with a wire brush and some slight corrosion on the piston skirt with Duraglit. Good as new!

    The real key is to get all the years of brake dust and crap off the caliper and mounting bracket. Its either plenty of elbow grease or take it a local media blaster. Remember to use plenty of silicon grease during reassembly. Getting the piston back in with the dust seal is tricky. I replaced the bleed nipples as well, but its not essential.

    Best of Luck.

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    • #3
      Originally posted by siwilson View Post
      Best of Luck.
      Is that in the service kit to....?!
      2002 '52 S54 - Titanium Silver with 18" BBS LMs, AP Racing BBK, KW V3, H&R anti roll bars & ACS flippers (previously 2000 'X' S50 - Arctic Silver)

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      • #4
        I've bought the service kits from the same place a couple of years ago when the calipers kept binding. Quite simple to do and as above the pistons clean up (I actually wet'n'dried mine as there was a bit of corrosion but they've been fine so far).

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        • #5
          Nice one - thanks guys

          Any tips on how to get the piston out?
          www.tracking-shot.com

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          • #6
            An air line will do it and failing that a bicycle pump. Cut and pull the outer dust seal away first and then be careful not to spray brake fluid anywhere.

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            • #7
              No need to cut the old dust seal. Just take out the piston completely. The old seal is a perfect protection if you want to sandblast the calipers and paint them afterwards.

              Gently push the brake pedal when the caliper is removed from the discs. A piece of wood between the piston and the counterside of the caliper (where the other brake pad usually is installed) protects the piston from getting damaged when pressed out.

              If this does not work due to heavy corrosion try it with an air compressor. The sticky caliper of my brake system needed 8bar / 112psi of pressure to come out of the caliper.

              By the way all 4 pistons were corroded when I rebuilt my calipers last year. New seals, new pistons and fresh paint, looks like new.

              Best regards,
              Phil

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              • #8
                New piston and caliper service kit ordered from Brake Parts yesterday afternoon, arrived this afternoon. Top service inc text alert advising an hour delivery time slot

                Now just need to get up the nerve to take my brakes to bits - thanks for the suggestions, very helpful. Need the car for a job next week so better get it sorted...
                www.tracking-shot.com

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                • #9
                  Funnily enough just doing mine at the moment. Last time I serviced the calipers I didn't change the pistons and just wet-sanded any corrosion smooth - not ideal I know and now it's come back!! (as in the old post above!!). So I've got two new pistons to go in (also from Brakeparts!). You'll likely need new rubber boots as the old ones will probably have expanded and will be hard to refit to the caliper.

                  The trick is to put the rubber boot over the new piston first (check it's the right way round!), slide it to the internal end of the piston and then fit both at once into the caliper; fit the boot lip inside the caliper groove whilst the piston is just at the mouth; once it's slotted in place the piston can then be aligned and pushed inside the caliper. I use a small flat screw driver to feed the rubber boot in to the slot.
                  Last edited by c_w; 19-10-2011, 07:51 PM.

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                  • #10
                    Was checking vids on YouTube this morning and looks like this one is showing a similar technique to get the piston/rubber boot back in - http://www.youtube.com/watch?v=QXcClOfFmlg

                    Haven't got that far yet - car is currently up in the air, wheel off and cleaned up, locating spring off, sensor disconnected and caps off the retaining bolts and I have just discovered that my allen key set jumps from 6mm to 8mm, and I don't have the 7mm one that I need anywhere!

                    Just nipping out to get one and some brake cleaner as the caliper is proper filthy
                    www.tracking-shot.com

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                    • #11
                      Aaaargh! OK have got the bolts out but the caliper won't come off. Am I missing something or does anyone have any suggestions?

                      The disk is spinning free-ish so it's not that the pads are locked onto it so tightly it won't move
                      Last edited by twink; 20-10-2011, 04:52 PM.
                      www.tracking-shot.com

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                      • #12
                        Originally posted by twink View Post
                        Was checking vids on YouTube this morning and looks like this one is showing a similar technique to get the piston/rubber boot back in - http://www.youtube.com/watch?v=QXcClOfFmlg

                        Haven't got that far yet - car is currently up in the air, wheel off and cleaned up, locating spring off, sensor disconnected and caps off the retaining bolts and I have just discovered that my allen key set jumps from 6mm to 8mm, and I don't have the 7mm one that I need anywhere!
                        Yes 7mm does seem to be left out of some allen key sets for some reason. The youtube video is exactly how it's done, although as said I used a small screwdriver to gently feed the last part of the boot lip into the caliper.

                        If you're talking about the 7mm allen bolts fully withdraw them out of the caliper, they will snag unless you pull them back a bit. The only other reason could be if your disc has a lip you'll have to retract the piston a bit to get it over the lip.

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                        • #13
                          Have got the bolts right out and there's play but it won't come out. I'm pretty sure it's because of the lip but I'm having a right game getting the caliper back any further

                          Any suggestions? I can't get the brake line off to remove the pressure as it's twisting the pipe when I try to do so as that seems to be seized as well. This is driving me nuts - gotta love those "simple" jobs

                          EDIT - Another 45 minutes later and I'm having a proper sense of humour failure now. Can't get the C clamp to stay on as it's got the smallest of lips visible on the piston to hang onto. It's getting cold outside and I haven't even got the effing thing off yet. Grrrrrr

                          EDIT - 9.30 and I've given up for the night. Have tried releasing the bleed screw to ease the pressure but still can't get the caliper off no matter what I try. Brilliant
                          Last edited by twink; 20-10-2011, 08:36 PM.
                          www.tracking-shot.com

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                          • #14
                            Oh dear, this is supposed to be the easy bit lol

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