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Rear brake shoe caliper wear 82 XJ1100J maxim

Discussion in 'XJ Technical Chat' started by Cudaguy, Jun 19, 2019.

  1. Cudaguy

    Cudaguy Member

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    Rear caliper was hanging up and would not release, but some taps with a rubber deadblow would ease it up, and eventually it would release. I am replacing the original brake lines and pulled the caliper today. The pads are worn diagonally in the caliper. The piston appears to be extended properly, not cocked to a side.

    Any ideas on why this happened and how to keep it from re occurring?
     

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  2. Chitwood

    Chitwood Well-Known Member

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    Those pads are like that brand new. It has to do with how that particular caliper pivots rather than slides. I dont have my manual handy to tell you the wear limits on the pads
     
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  3. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    +1. The caliper piviots on the pin, so the pads have to be made at that angle in order to lay flat to the disc as they wear. The Maxim 650 front pads are made the same way.
     
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  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    rear limit 1.2mm

    1100 pads rear.PNG
     
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  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    I'd like to add that the brake not releasing isn't likely going to be solved by just replacing the brake lines. The return port in the master cylinder is blocked.
    The safe thing to do is rebuild the whole system. Rubber parts have a lifespan, and yours seem to have exceeded theirs.
     
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  6. Cudaguy

    Cudaguy Member

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    OK then. I have the new pads, but I did not open them up yet. I just checked them and they are angled as well.
    As far as the line s, that was a separate update and not related to the rear brake issue. I was hoping to find an issue with the caliper as those are parts that can still be acquired. The rear master seems to be unavailable anywhere.
    I'll look into it after I get the lines done. My replacement kit did not include the hardline under the tank and the rear fitting got pretty hacked up in the removal and replacement. We'll see how things go from here, thanks for the info on the rear pads.
     
  7. mlew

    mlew Well-Known Member

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    You can still easily get rebuild kit for the XJ11 rear master cylinder and calipers. I did mine less that a year ago.
    Send a PM to Chacal at XJ4ever, he has the parts and will get them to you quickly.
    Go ahead and rebuild the front calipers at the same time, it will save you headaches in the near future.
    Remember when you start bleeding the brakes that the rear and front are linked together. Bleed the front first then the rear.
     
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  8. Franz

    Franz Well-Known Member

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    Are the rear and front brakes linked like Moto Guzzi's used to be and probably still are?
     
  9. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Pretty much. I think the newer small-block Guzzia are not linked.
     
  10. Cudaguy

    Cudaguy Member

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    Status update
    Replaced all original soft lines with stainless braided lines. The hard line remains in place, thought the fittings got pretty messed up in the process. I don't understand why they are such a soft metal. I sliced open on off the lines (they were date coded 02/82) and they looked excellent, no detritus, discoloration, or other sign of deterioration.

    Replaced all pads with new semi metallic sintered pads.

    Disassembled the rear caliper and installed new seals after a thorough cleaning. There was a lot of gunk in the caliper.

    Disassembled the rear master cylinder, cleaned out a minor amount of gunk, thoroughly cleaned remaining parts which were in great shape and re assembled.

    Disassembled left front caliper, deep cleaned and re assembled with the existing components which were in good shape. Have ordered the correct front caliper kits and will repeat
    that step when they arrive.

    Disassembled the right front caliper, which was seized up tight and would only release the piston after applying front master cylinder to the line with no other components attached. Compressed air would not release the piston, and even using the hydraulic pressure, it was a slow process. It was very gunked up. Cleaned it nad reassembled as above.

    Used a mityvac to bleed the lines, then followed up with "conventional bleeding methods" to get a solid pedal/ grip.

    Test ride today showed much better front grip braking power, a significant improvement. The unified/ foot operated works as well as before, but does required greater distance in foot movement to achieve desired braking. I believe I need to adjust the pedal rod to MC , but I'm not sure why. It would seem the pedal travel should be shorter since there are thicker pads in place now. I will make that adjustment after a couple rides.

    any observations are appreciated
     
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  11. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The amount of travel of the foot pedal dosen't need to be adjusted in hydraulic systems for pad/shoe like it does with mechanical brakes.
    The extra travel you need is probably due to a small amount of air still being in the system. Yamaha calipers have a few places where air likes to get trapped until the machine has been ridden (or the air bubbles vibrated out with a sander). Re-bleed the brake and see if the pedal feel improves. You might also have to remove the master cylinder cover, tie the lever back, and tap the caliper and lines to float any trapped air out. Sometimes I find that I need to move the lever a bit by hand to help the air move past the piston and through the return port (note that is my experience for other machines. I don't have an XJ100, but the hydraulic systems are pretty much like what I've worked on).
     
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  12. Cudaguy

    Cudaguy Member

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    Follow up.....
    I was riding today and had a bit of a panic stop situation. I will say that the brake line upgrade and other brake upgrades showed up strong in how well the bike stopped safely under a panic stop. Well worth every bit of effort and money it took to do.
     
    Last edited: Aug 20, 2019

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