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Mattthebat

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    "warped back disc"

    in Pitstop

    Posted

    Hello


    With out knowing who did the MOT,the swing on the brake tester or a run out figure....


    An intermitant warped rear disc on an R1200GS could be:

    A dirty caliper or disc, the pins seize in the caliper body. This is the most likely and cleaning the caliper will lessen the effect.

    Do you have a pyramid hugger? or touratech? these apply pressure on the caliper when the pads are half worn also cause the caliper to drag after that. causing pedal fluctuation

    The disc mounts could have corroded causing the disc to rise in one spot,

    the disc carrier could have warped really unlikely but do check the carrier flange by the bolt holes for cracks. A fault reported by very few people on other forums.

    or worse case the wheel bearing could have excessive play.


    or just a warped disc


    If you have servo assisted brakes please be aware that pre 2009 the system is calibrated for organic rear pads after that and on non ABS sintered pads are used.


    But as its only an advisory item and you only feel it at low speed why change the disc if it has plenty of life left. measure the disc and compare that figure to the minimum thickness on the disk. i think its 4mm from memory.


    If you do change the disc its worth noting that to do this you need to remove the rear wheel as the disc comes of that side.Then remove the plastic guard three torx 30 then the caliper. Then the 5 disc bolts are loctited in and the release temprature is 80 degrees.

    The bolts are one time use ( according to BMW) and are accessable from the non exhaust side in a cut out/ dished section in the final drive just below the plastic mudguard.

    You can only undo one bolt at a time hold the disc in place by selecting first as this will stop the rear wheel turning the engine has enough compression to stop the wheel turning.


    The bolts are wheel torx 50, the brake disc is a torx 40 deep reach the caliper is torx 45. Im would reccomend covering the torx 40 with rubber hose so it doesn't mark the paint on the rear drive.

    The disc bolts are done up to 33nm, the caliper to 23nm the wheel bolts are 60nm.


    Sorry for the ramble

    Hope it helps ran a GS for a while and picked up a few things.


    Anything else just PM me

     

    Thank you very much for all of the above, I do have a pyramid hugger, this could be the prob, as you say I think I'll keep it on the thickness is well over 4mm , but I've got the details of how to change it now ! :)

    I'll do it in the spring I tink.


    Cheers to all who helped !


    :)

    "warped back disc"

    in Pitstop

    Posted

    Could be caused by a seized piston thats been pressing on the disc causing it to get hot and warp. happened to my gpz and actually split the disc.

     

    Ouch!


    Took it to another garage "general wear and tear " it's only intermittent at very slow speed under 5mph. Cheapest on eBay is £130

    "warped back disc"

    in Pitstop

    Posted

    maybe you went for a really hard ride out then washed it straight away? Because i am pretty sure putting cold water on hot disks can warp them

     

    That could be the reason. Possibly..

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