How To: Rear Brake Caliper maintenance

Discussion in 'GS Boxers' started by JasonF, May 30, 2012.

  1. JasonF

    JasonF Been here awhile

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    A friend of a friend mentioned the other day that his GS was in for service because of the rear brake. This got me to thinking I should probably spend some quality time with the rear stopper on my 2007 R1200GSA to see how everything was looking after 19,000 miles.

    This past weekend I took a look at things and was shocked to find out that my rear caliper was barely able to float on its guide pins as designed. If you aren't familiar with this design, it's a simple 2 piston caliper that only pushes on the right hand brake pad. As this pad is pushed to the left (inward), the entire caliper moves to the right, applying force to the left hand brake pad. This is enabled because the caliper floats on a pair of guide pins that are supposed to be lubricated and sealed by some rubber seals. What I found was that the front guide pin was dry and rusting, and essentially seized in place. The rear slide on the other hand was still well lubricated. After some head scratching I figured out how to disassemble the caliper slides, clean and lube everything, and reassemble. The whole process probably takes 20 minutes once you see how its done. I would recommend this be done every 12,000 miles.

    Remove rear mud guard (possum scraper). Pull out the cotter pin at the rear of the caliper that secures the brake pad slide pin. Now you can tap the brake pad slide pin out from right to left. A punch would work best, but I made do with a nail in my toolbox.

    [​IMG]

    Remove the two torx bolts that attach the caliper mounting bracket to the swingarm and lift up the caliper. Carefully remove the brake pads as they'll be free to fall out at this point. Once the caliper is clear of the swingarm, try to slide the black caliper side to side relative to the silver mounting bracket. It should slide back and forth about 1/2" and you should observe the little accordion rubber seals at the caliper slide points stretching to permit the back and forth movement. If it does not slide easily, time to proceed to the next step.

    [​IMG]

    Using a 11mm open end wrench, loosen the lower slide pin from the caliper mounting bracket as shown in the photo above. Unthread it completely. If you're lucky, once unthreaded, the caliper mounting bracket will slide right off of the guide pins and separate from the caliper. If the front slide is seized, you'll have to work it a bit to free it up and get it off. I had to spend a few minutes working the front slide on mine back and forth to get it to come free.

    Once the rear slide is unthreaded from the mounting bracket, it comes out of the caliper like so:

    [​IMG]

    My front slide pin was dry and rusted and had a rough surface on it instead of the smooth surface it's supposed to have to slide properly. Using some WD40 and a strip of 320 grit sandpaper I cleaned off the rust to restore the smooth finish. I also cleaned out the hole in the mounting bracket as it had some dry rust debris inside.

    [​IMG]

    This is the collection of parts you should now have:

    [​IMG]

    Clean both of the slide pins and lube them liberally with silicone brake grease. I like Sil-Glyde from NAPA. Apply some extra silicone grease inside of the slide pin holes as well.

    [​IMG]

    Put the rear slide pin back into the caliper and then reattach the caliper mounting bracket and tighten the rear slide pin into the bracket. Test that the caliper now floats easily on the bracket..you will be amazed how easily it moves.
    Apply some copper anti-seize to the brake pad slide points at the front, at their pin holes at the back, and on the back side where the caliper's pistons will push. Use extra care not to get anything on the pad material or your brake disk. Slip the pads back into the caliper, and then coat the brake pad pin with anti seize and slip it back into the caliper to secure the brake pads. Before seating this pin, align the cotter pin hole vertically so that the cotter pin will be able to fit back in. Once aligned, seat the brake pad pin all the way into the caliper with a tap from a hammer. Reinstall the cotter pin.

    [​IMG]

    Fit the brake caliper back over the disk. It will take a little maneuvering to hold the brake pads apart so that they will fit back over the disk. Once it's on the disk, reattach the caliper mount to the swingarm, reinstall the mud guard, and you should be good to go. Press your rear brake pedal a few times to move the pads into position and test your rear brake carefully before charging into that first turn. If it's weak, you may have inadvertently gotten something on the disk or the pads, and their effectiveness may be compromised until it's cleaned off.

    I'm interested to hear if anyone else finds their front slide pin as dry and rusted as I did.

    Ride safe

    Jason
    #1
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  2. portablejohn

    portablejohn Long timer

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    Excellent post! I hadn't really thought about it, but it would be very easy to overlook the condition of the rear brake. Once it gets stuck, the problems just seem to multiply...
    #2
  3. malloy

    malloy Been here awhile

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    Good one, Jason:clap.

    There's a similar, though long winded, detailed w/many pictures version in the Hall of Wisdom.
    #3
  4. tallguy-09

    tallguy-09 Smile 4 Miles

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    I've looked but can't find it in the Hall of Wisdon, anybody?
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  5. pcwirepro

    pcwirepro Aspiring Adventurer

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    I just looked for the article in the hall of wisdom this weekend and couldn't find it so I just got after it. Front was completely seized, and the rear pin wasn't in much better shape. They're both pitted now so I expect this will be an ongoing problem. I used anti seize on them (wasn't aware of your special brake silicone) but was curious about other high temp options. Wish I had caught it before I tore up my new pads in one week. Argh! Are the pins and rubber boots available as replacement parts or is a whole new caliper?
    #5
  6. Chubb1

    Chubb1 Going going gone

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    I found the same problem on my 07GS. Mine was seized well and good. Took about 30 min to separate. I now check mine every time I do the FD oil change. Good write up.
    #6
  7. JimVonBaden

    JimVonBaden "Cool" Aid!

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    It is a link at the bottom of this page.

    Jim :brow
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  8. FatChance

    FatChance Road Captain

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    Look at "BFD-rear" in the Hall of Wisdom...
    #8
  9. pcwirepro

    pcwirepro Aspiring Adventurer

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  10. tallguy-09

    tallguy-09 Smile 4 Miles

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    #10
  11. JimVonBaden

    JimVonBaden "Cool" Aid!

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    The write-up is technically accurate, but makes me anxious just reading it. Lots of excess joking and discussion that makes it a bit hard to follow.:deal

    No, not that complicated at all. The write up may make it seem hard, but it is an hour of basic tear down and rebuild that shouldn't be too difficult for even a more basic wrench turner.

    Jim :brow
    #11
  12. scooteraug02

    scooteraug02 Dog Rancher

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    My rear pin on an 08 GSA has groove/rings on it. What are they for?
    #12
  13. pcwirepro

    pcwirepro Aspiring Adventurer

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    To hold the rubber boot in place?
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  14. tallguy-09

    tallguy-09 Smile 4 Miles

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    Used the above pictures/text and had no trouble removing everything. Only 10.000Km here and everything slides like new.
    Torque for the 2x M8 x 25 brake calliper to final drive screws is 24Nm (BMW RepRom)
    Use Loctite 243 to secure Splasguard screws (BMW RepRom).
    #14
  15. EJ_92606

    EJ_92606 Rider

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    Can you clarify, did the pins slide like new when you tore it down or are you saying after you cleaned/greased? My bike has about 10,000 miles, so I'm wondering if I need to look at this yet.

    thanks.
    #15
  16. tallguy-09

    tallguy-09 Smile 4 Miles

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    Yes, like new after 10.000Km/3years (hardly any rain) could slide black calliper back and fourth easily, just put it back together, 20min work.
    #16
  17. JimVonBaden

    JimVonBaden "Cool" Aid!

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    IMHO You should clean and lube them at 6K, because the factory sends them dry. Then do it every 24K, unless you are changing pads, and they will never wear out or notch on you. Helps to keep brake wear even as well.

    Jim :brow
    #17
  18. tallguy-09

    tallguy-09 Smile 4 Miles

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    I've checked my slider pins and after 11.000Km they were totally fine and factory silicone greased (2010 R1200GS)
    Those 2 rubber boots do their job.
    I'd only check them when you notice the black caliper not sliding easily on the pins, then something needs to be done.
    #18
  19. aculate

    aculate Herk, herk,...Ptooey

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    Wear indicators. There are three ring grooves, representing 75%, 50%, and 25% of the pads left. When the 25% ring disappears, it's time for new pads.

    The front brakes are different. The wear indicators are grooves/slots in the pad material itself, not the pins. When the slot is only showing 1 mm left, it's time for new pads.
    #19
  20. JimVonBaden

    JimVonBaden "Cool" Aid!

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    Including the retaining pin for the pads? That is the one that is nearly always dry!

    Jim :brow
    #20