Front Brake problems and Desperation...

Discussion in 'GS Boxers' started by Cruiser242, Jun 11, 2018.

  1. Cruiser242

    Cruiser242 Adventurer

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    I will do that tomorrow as I am out of time tonight and will need to tighten down forks, bridge, axle ect. before i move onto the bleed screw. I will update again tomorrow ...cheers
    #21
  2. Dan-M

    Dan-M Long timer

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    Reading through this thread, this is the first thing I thought of. If opening the bleeder frees up the wheel, the issue is often a internally collapsed hose. I see the OP changed the hoses though.

    The rotors should both be centered in the calipers. I believe 1/8" difference between inner and outer pad space on the left is your issue. Assuming all parts are the correct ones, and if it is indeed present on both calipers then the wheel is not centered. If it is only one side then it is how that rotor is mounted. It could be that once things heat up and expand, there is not enough clearance for the left inner pistons to retract. It may be a good idea to remove the pads, mount the empty calipers with the pistons fully retracted and measure the distance between the pistons and the rotors. Then measure pad thickness. If that left inner measurement is close with no room for expansion, it could cause drag once things warm up.
    #22
  3. Jim H

    Jim H Been here awhile

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    Cruiser242 - Yes, as others have said, the rotor slot in the calipers should be centered on the on the rotors and piston extension from the calipers should be equal on inner and outer sides. Earlier you had said that the right side looked OK but now it appears you have the same rotor vs caliper offset on the R and L sides. I'm sorry to repeat but that can only happen if the wheel centerline is offset. The calipers cannot be offset if they are mounted correctly to the fork slider attachment lugs.

    Can you take and post close-up photos of the left and right side of axle/wheel hub interface. Try to shoot photo from above R and L sides of front wheel from about 45deg fwd of vertical so the spacer on right side and the speedo drive on left side are visible. I'm still of the belief that something is off on one or the other of these spacers. For instance, the R side spacer OD should fit within the hub, not on the hub. The left side spacer should extend outward about 3/32" from the speedo drive housing to contact the inside of slider leg at axle hole.
    #23
  4. Jim H

    Jim H Been here awhile

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    Right and left spacers should look as shown in photos. Hard to get photo straight on showing left spacer protrusion but it's about .080" beyond speedo housing raised surrounding boss, between speedo housing raised boss and slider inside flat end of axle clamp.

    Attached Files:

    #24
  5. Cruiser242

    Cruiser242 Adventurer

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    ok new update, I did crack bleeder on left side and spun with no change, still dragging, and I know you probably think that calipers need to be rebuilt again, but if I had to describe the condition before rebuilding them twice I could almost say they looked brand new so I really dont think its a caliper pressure or rebuild issue, and yes I know about setting the seals in the right direction and cleaning and the whole rebuild process of a caliper.

    So After a short ride I then removed pads again from left caliper (problem child) and this time noticed that outer pad is wearing on the bottom of the pad and the inner pad is wearing on the upper part of the pad telling me that the rotor OR the caliper is angeled. I installed again and using a spark plug gap guage was able to slide it between piston and pad on upper part of outside piston but not all the way through, which corresponds with the uneven wear of the pads.

    As stated before I have taken both calipers off and spun wheels which spins great and observed both wheel and rotors on both sides of bike marking a spot on the ground and found nothing warped or bent what so ever, as well as putting a runout guage on the front forks and testing distances on both rotor and wheel and found nothing showing a problem.

    Also after having loosened all forks, bridge, axel pinch bolts ect. bouncing on front end and twerking handle bars left to right while holding wheel between my knees I went and observed that the right side pistons extend out evenly now meaning rotor seams to sit in the middle of the caliper and pads. I have not gone for a ride since right side pistons straighted out, im just hoping they stay that way.

    So I have figured out a bit more info but still am at a loss of whats going on, im thinking either im missing something on checking rotor and wheel and its warped so slightly I cant see it or that my caliper is bent or warped or the mounting points that hold the caliper on the fork are bent. I have tried to install a washer on upper caliper mount to straighten things out but didnt make much difference.

    Once again thanks for the help and look foreward to hearing some more opinions.
    #25
  6. Cruiser242

    Cruiser242 Adventurer

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    Also Jim I did take pics of the wheel axel spacers, gaps, speedo but it is exactly the same as you posted and everything I have seen in diagrams and that I have found online, and with the new findings mentioned above I have not posted pics
    #26
  7. Jim H

    Jim H Been here awhile

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    Seems like you're getting close to calling it done. Don't need photos of your install if you compared your assembly to my photos and yours matches; that's all good. It looks like what you had was one or the other or both of the sliders rotated slightly off of exactly forward facing. This can happen if you released the lower fork bridge slider clamp bolts at some time during fork seal change and didn't get the sliders reinstalled back to the exact correct rotational position and parallel alignment before you finished fork reassembly and front wheel, axle and brake caliper reinstallation. If you were able to install the front axle without too much difficulty the sliders were not very far off of proper alignment.
    #27
  8. Cruiser242

    Cruiser242 Adventurer

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    Well I wish I had the same optimism as you Jim in regards to almost being done. So the funny thing is I replaced fork seals from the top only loosening stantion nuts and pulling up and out, never loosened bridge or anything else. Still at a complete loss of whats going on with cantered caliper or rotor. I'm thinking at this point maybe I bent rotor or wheel when cranking tire irons during tire replacement and I'm just missing something, not sure how thats possible after a good visual spin inspection and runout gauge inspection. Looks like I'm gonna miss another great weekend of riding, )uhhhhgggg so frustrating....
    #28
  9. Jim Moore

    Jim Moore The Real Deal

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    I'm not sure it's possible, but is your wheel on backwards?
    #29
  10. Jim H

    Jim H Been here awhile

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    Hmmm. Running out of ideas here if you didn't loosen the slider clamps at the lower bridge, unless the sliders were originally off proper alignment. Nothing seems to be amiss with the caliper assemblies but from your last inspection it seems the caliper pad "slot" fore/aft axis is misaligned with the rotor fore/aft axis. If you still have the old pads were they worn off angle front to back, meaning the contact surface of the liner is off parallel with the backing plates?

    To be sure sliders are aligned properly you can use the bare axle (not with front wheel installed), run axle through R slider until the female threaded end is just inboard of the L slider axle clamp. Tighten R slider lower axle clamp bolt a bit to make sure the axle is fully seated in the R slider clamp but will still move with light tapping. Look through the L slider axle clamp to see that the axle female threaded end is centered in the bore of the L slider axle clamp and parallel with the bore of the clamp. If one or the other slider (or both) is rotated out of proper alignment, the female threaded end will not be centered or not be parallel with the L slider clamp hole and it will not slide in to the L slider clamp easily when you slightly release the R slider axle clamp bolt and tap it in place.

    The only other thought is your axle may be bent slightly, which can be checked with a metal straight edge, or a fork tube can be bent, which you can check by rolling each fork tube on a flat surface. Once again, if everything was working correctly before you started on this effort and you didn't release the slider clamps and nothing appears to be assembled incorrectly but you now have a misalignment, I'm running out of ideas...
    #30
  11. Ron50

    Ron50 Been here awhile

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    Three thoughts from me, Cruiser242:
    1. When you cracked the bleed screw and the dragging persisted, even if there was some misalignment the fluid pressure should have reduced and lessened the drag. So if no fluid came out maybe the valve is blocked by crud.
    2. If the caliper is not aligned with the rotor the ears on the fork leg are bent, as you've tried to compensate for with washers.
    3. Is there a chance that the rotor was bent in EVENLY in the tyre fitting process? Usually this would occur unevenly and show up as a wobble in the rotor as it turns but you've checked for runout.
    #31
  12. JimVonBaden

    JimVonBaden "Cool" Aid!

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    Did I miss it, or did someone already say deteriorating rubber brake line contaminated the caliper?
    #32
  13. Ron50

    Ron50 Been here awhile

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    Pretty much: Drone in post No. 7. He referred to bits of rubber obstructing the flow of fluid in the caliper.
    #33
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  14. Cruiser242

    Cruiser242 Adventurer

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    Oooohhhhhh Houston i think I found a problem. So Jim thanks again without your last comments I probably would not have taken the wheel off, so here is what I have found. Right side bearing center cog sits flush with outer raceway and is tight to inner center spacer. Left side center cog is pushed out about 1/8" and not flush with outer bearing raceway. This explains why left fork and caliper mount is not pushing in all the way and causing caliper to pull out on rotor.
    So I am going to replace bearings, I know they need to be pressed in but anyone with experience on these for DIY with socket and hammer trick?
    I will report back after bearing replacement and let you know how things worked out, once again thanks for your time and help.
    #34
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  15. Ron50

    Ron50 Been here awhile

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    Eureka!

    When you get it apart check whether the outer race has been forced too far into the hub or even worn the hub away by seizing and rotating in the hub. Or what has caused the inner race to be proud of the outer race.

    Just make sure you don't hit the inner rings of the new bearings when installing them; use the old bearings as drifts so that all the force goes directly to the outer rings. This prevents the balls and races being deformed in the installation process.

    If you're sure you have a socket that is the perfect fit to line up with the outer ring you can use that (easier to get the installation force centralised by hitting on an extension bar then) but you can be sure the old bearing is the right diameter.
    #35
  16. Jim H

    Jim H Been here awhile

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    Sounds like perhaps a smoking gun has been found but unfortunately there remains some concerns. The left bearing is a double row bearing and of the two, it's considerably more resistant to failure of this type. This bearing is also fitted with a center bush during assembly that steps down the bearing ID from 25mm to 20mm axle diameter. The flanged end of the bush covers the outer end (L side) of the bearing inner race and is proud of the bearing inner race by close to 1/8". (see pc 8 on parts fiche diagram #36_0178 at https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51668&rnd=07242017) .

    In other words, you may not have a damaged bearing at all. You may just be seeing the flange on the center bush in the bearing inner race... Suggest you look at it again to make sure you're not seeing this flanged bushing instead of the inner race.

    The other concern is if the bearing is indeed damaged to the extent that the inner race is offset that far from the outer race, both rows of bearing and/or their races would have to be ground to near dust to provide space for that much offset. Also, the wheel would definitely not spin freely as it did when you had the calipers off. One can never say never about such things but...

    If you're sure the bearing is broken, and need to remove it (or both) and don't have a blind bearing puller of the correct size it will be a struggle to get these bearings out without damaging the center spacer. This spacer is an aluminum tube and fits tightly between the inner races of the two bearings so you can't use a traditional blind bearing puller. Also, the outer races stop on a circular ledge within the hub bore so you can't easily tap them out from the opposite side either. Motion Pro sells a drive-type bearing puller that works for these bearings but you'll need both a 20 and 25mm size head. There is a YT video showing use of this tool but the bike involved was not one with the center bushing in the L side bearing. . You can pull either side bearing first but if you pull the R side first with the 20mm puller you can extract the center spacer and use a long drift to tap out the L bearing center bush without using a puller. Then use the 25mm puller to extract the R bearing.

    Hope this isn't new information regarding the presence of a flanged center bush in the L bearing that you may have been seeing. The good news is that it may save you some time and money chasing ghost feathers if indeed that is what you were seeing sitting proud of the L side bearing inner race...
    #36
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  17. Zoef zoef

    Zoef zoef Been here awhile

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    Sometimes you can move the spacer, then use a long drift to tap the bearing out.
    #37
  18. Cruiser242

    Cruiser242 Adventurer

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    yup started thinking the same thing because bearings moved good and once I saw the parts diagram it was confirmed, im just seeing the reducer thats sticking out past the bearing.....dang it thought I had it, thanks Jim saved me the money of new bearings, I guess back to pounding my head on the drawing board.
    #38
  19. Cruiser242

    Cruiser242 Adventurer

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    so I just dont get it, the caliper sits between the fork bridge and the axel, both of which are fixed lengths with no room for play, lets assume all parts are complete and aligned, that leaves only the wheel, rotor, and caliper to be mis-aligned, checked wheel, and rotor both visually and with runout guage showing all good, only part left is caliper, so how can that thing get mounted out of alignment if every other little thing is good.
    #39
  20. Jim H

    Jim H Been here awhile

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    Caliper can be misaligned if caliper mounting tabs on one or both sliders are bent but that seems unlikely to me. If the front end and brakes were operating correctly before the brake pads and tire were changed, I don't see how the mounting points could now be misaligned.

    Something else may be causing brake drag as suggested by others and that is the possible contamination of the brake system with rubber bits from the original OEM brake hoses. Rubber bits in the brake system could cause both port blockage and stodgy piston movement/drag. A thorough system flush with new brake fluid without calipers installed and thorough back flushing of caliper internals may disclose the presence of such rubber contamination. This is a fiddly and messy process but this is exactly what cured a rear brake drag problem on my 1150gs several years back. You can use compressed air to "back flush" the calipers but it will still be messy...
    #40