Seized brake caliper

displacedaussie
displacedaussie Posts: 356
edited December 2012 in Workshop
After many years and miles of service, both of my (Shimano 105 BR-5501) brake calipers have started seizing up and refusing to re-open.

I've cleaned and checked through everything, and they're both sticking at the Arm Bolt Unit (ie part 1 in the parts list [1]) - the bolt on the right in the image below.

shimaon_105_br.jpg

What is the correct way to remove, clean, lube and then re-tighten this bolt? The service instructions [2] don't mention it at all.


1. http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/BR/EV-BR-5501-2172_v1_m56577569830609048.pdf

2. http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Dura-Ace/BrakeSystem/SI-8FA0H-ENG_v1_m56577569830605105.pdf

Comments

  • desweller
    desweller Posts: 5,175
    1. Take pads off
    2. Drown pivots in WD40
    3. Open/close caliper several times
    4. Run some heavier oil into the pivot.
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  • andyrr
    andyrr Posts: 1,822
    If I recall ,from having done this myself, the bolt, pictured here at the upper RHS holds the 2 caliper halves together and it can be removed (not sure if that one pictured is a hex or torx or what) and then you carefully separate the bits, taking are that nothing pings away. then clean and lube.
    Sometimes it seems dousing in WD-40 and the like effects an improvement but doesn't resolve sticking so dismantling is needed. Bit of a pain but not a major job.
    If it sticks when there is no cable attached then it is obviously somewhere within the caliper parts themselves that are causing this.
    I've seen some people say that once they did this the brake was never the same, ie never as good, as originally, but when I did it the sticking issue was resolved. Maybe easiest to initially loosen that bolt with the caliper still аttached to the frame and then remove to do the cleaning.
  • Full disassembly is fairly straight foward - start by unhooking the spring at the back.

    The rest can be taken apart with Allen keys (note the tiny Allen bolt holding the central bolt in place) and a small spanner.

    Clean, inspect and replace the bushing washers if the arms are rubbing against each other.

    Lubricate and then reassemble. Tighten just enough so that the pivot points can move freely but to not leave too much play inbetween the arms.