Brembo Caliper Overhaul

    I decided to overhaul my brake calipers and flexible hoses. This involved new seals, pistons and braided stainless flexible hoses.


    When working on the four-pot brembo front calipers I found each caliper had one seized piston. I got an overhaul kit on Ebay which included everything needed, seals, pistons, bleed screws). However, I had previously purchased Stainless bleed screws and braided hoses from Gerry of Phoenix Motorsport a couple of years ago (shows how long I have been meaning to do this job).


    Once the calipers were off the car, I plugged the hose hole and sandblasted them before removing anything so as to keep the sand out of the caliper. Then I air blasted them to remove any grit residue, srayed them with brake cleaner before giving them a primer undercoat.


    Next, I mounted them in a vice and clamped three of the four pistons so they couldn't move. I connected an airline to one of the bleed screws via flexible hose and opened the screw and used compressed air to lift the un-clamped piston. Removing the dust cover and the piston, then fitting new seals and piston. Repeat the procedure for the next piston.


    The seized pistons required soaking with releasing oil and a fair bit of air pressure (make sure you prevent the piston from flying out - they can go with a "POP" - experience!!).


    When all pistons had been done, I removed the old bleed screws and fitted blanking plugs before painting with caliper paint. 5 coats and then 24hrs hardening time before refitting to the car.
    8er.org/forum/index.php?attachment/41183/


    When trying to undo one of the connections between the flexible hose and the steel brake pipes I found it had seized completely and WD40, Easing oil and heat application would not shift it. I had to cut the connection off and fabricate a new connection by cutting in a new brake pipe.


    8er.org/forum/index.php?attachment/41184/


    Once everything was fitted back on the car, it was simply a matter of bleeding the calipers (rear and front) according to the BMW procedure.

    Well done! :top:
    In my opinion, the reason for seized pistons in our Brembos is the badly designed caliper.
    The connection screw-domes are sitting far too close to the sealing rings of the pistons and so a large amount of break dust builds up over time around the sealing.
    Heat can not dissipate under this cover and the sealing deteriorates over time and moisture enters there.


    I had two calipers seized and one of them could not be rescued anymore.
    Taking out the pads and cleaning off built up break dust every now and then helps a lot in my experience.


    I don't really understand why BMW did not used some existing Brembo calipers instead of creating a new one for the 8.
    I bought the last left sided one from BMW a couple of years ago. (I don't know if they produced a new batch since then).
    The whole caliper was painted black including all rubber parts and break fluid hoses.
    I had to rub the the paint off the rubber parts. It was very cheaply made. (I bought it from an official BMW dealer so it's original. No fake.)


    Cheers,
    Steve

    Hi Angus!
    That looks like a top job!
    Remarkably I am doing right now exactly the same job on my 840 :mrgreen:
    I hadn't the chance to sand blast the calipers on my own, so I just brushed them rust clean, sprayed an epoxy rust primer, then spayed the caliper paint in three coats.
    I like to say that I used the Foliatec paint, and I was very glad with the results. Indeed I used for my E46 another brand, which didn't made me as satisfied as Foliatec :dontknow:


    8er.org/forum/index.php?attachment/41186/


    Now I'd really like to know:
    How did you pressed the dust covers seals in their seats once the pistons were already pushed into the pot?
    They have a nasty snap ring which is making me mad... :hmpf: :ahhhhh:

    Hi Danilo:
    The front Brembo calipers are aluminium so you shouldn't have any rust (maybe a little oxidation?).


    I fitted the dust covers to the pistons BEFORE I inserted the pistons into the calipers. This ensured the fit around the piston was correct. As the piston slipped into the caliper I pushed the dust cover outer ring around the lip on the caliper. Finally I used a large (40 mm or 42 mm) socket placed over the dust cover then gently used a lever between the socket and the opposing caliper piston to apply downward pressure on the dust cover to ensure it was snugly seated.


    8er.org/forum/index.php?attachment/41187/

    Thank you very much for your answer, I sincerely appreciate.
    So it's now for me just a matter of finding out the right socket to press the dust covers :top:
    And yes: Rust was basically only on the rear calipers :mrgreen:

    .


    Das was du heute denkst, wirst du morgen sein.
    Buddha


    .

    So... for the record: Job done!


    The problem was, I greased the dust covers with ATE Bremszylinderpaste:


    8er.org/forum/index.php?attachment/41201/


    just like I was used to do with floating calipers and ATE repair kits according to their instructions.
    Unfortunately this way the greasy dust covers just sprang back out of their seats... :hmmmm:


    Rubber ungreased, seat cleaned and... here you are! :mrgreen:


    8er.org/forum/index.php?attachment/41202/

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