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  1. #1
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    Brake help - please!

    Sorry if this is the wrong place to post this. I have a 1991 Stumpjumper Comp and decided to put the OEM brakes on. (Shimano XTís black) I trade for a set that appeared to be in very good condition. For the life of me I cannot get the front brake with the spring adjustment to spring back. Iíve watched videoís and set up other brakes and had no problems. Cant get this one brake to work. It only springs back if the hanger is completely misaligned. The rear brakes work fine. Iíve tried 2 different hangers - Dia Comp and Shimano and same results.
    Perhaps I should shine the OEM thing and put something else on.
    Any help would be really appreciated.

  2. #2
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    Quote Originally Posted by bp101 View Post
    Sorry if this is the wrong place to post this. I have a 1991 Stumpjumper Comp and decided to put the OEM brakes on. (Shimano XTís black) I trade for a set that appeared to be in very good condition. For the life of me I cannot get the front brake with the spring adjustment to spring back. Iíve watched videoís and set up other brakes and had no problems. Cant get this one brake to work. It only springs back if the hanger is completely misaligned. The rear brakes work fine. Iíve tried 2 different hangers - Dia Comp and Shimano and same results.
    Perhaps I should shine the OEM thing and put something else on.
    Any help would be really appreciated.
    Maybe try Park Tool's site.

    Brakes Repair Help Articles | Park Tool
    Ripping trails and tipping ales

  3. #3
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    Quote Originally Posted by Vader View Post
    Maybe try Park Tool's site.

    Brakes Repair Help Articles | Park Tool

    Thank you. Iíll take another look there.

  4. #4
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    Check the end of the cable outer, the inner cable might be catching and if the hanger is misaligned, might be enough to "miss" the obstruction.

    Being a spiral wound casing, it's easy for a bit of the spiral to curl in when you cut the outer. Open it up with an awl or pick or something.

    Of course, now you're gonna tell me it's the old outer and never had the problem before and blow my theory out of the water.

    Grumps

  5. #5
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    Quote Originally Posted by bp101 View Post
    Sorry if this is the wrong place to post this. I have a 1991 Stumpjumper Comp and decided to put the OEM brakes on. (Shimano XTís black) I trade for a set that appeared to be in very good condition. For the life of me I cannot get the front brake with the spring adjustment to spring back. Iíve watched videoís and set up other brakes and had no problems. Cant get this one brake to work. It only springs back if the hanger is completely misaligned. The rear brakes work fine. Iíve tried 2 different hangers - Dia Comp and Shimano and same results.
    Perhaps I should shine the OEM thing and put something else on.
    Any help would be really appreciated.
    Need pic's of your brakes, are you sure that you have the correct springs in the correct sides? As I remember those springs inside the brakes all look the same and you might have the wrong spring in the wrong side or belong in some other brakeset, swapped out before you traded for them

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    Quote Originally Posted by Uncle Grumpy View Post
    Check the end of the cable outer, the inner cable might be catching and if the hanger is misaligned, might be enough to "miss" the obstruction.

    Being a spiral wound casing, it's easy for a bit of the spiral to curl in when you cut the outer. Open it up with an awl or pick or something.

    Of course, now you're gonna tell me it's the old outer and never had the problem before and blow my theory out of the water.

    Grumps
    Old outer and never had this problem but I do appreciate you taking the time to help. I think the reply below is the issue. I'm just about ready to start over and get different brakes.

  7. #7
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    Quote Originally Posted by sbsbiker View Post
    Need pic's of your brakes, are you sure that you have the correct springs in the correct sides? As I remember those springs inside the brakes all look the same and you might have the wrong spring in the wrong side or belong in some other brakeset, swapped out before you traded for them
    I think this is the issue. I traded with a very reputable and knowledgeable guy. I think some how this brake has faulty parts inside.
    I have no idea how to go about finding new and correct spring. I'm about to throw in the towel and get different brakes.

  8. #8
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    Quote Originally Posted by bp101 View Post
    I think this is the issue. I traded with a very reputable and knowledgeable guy. I think some how this brake has faulty parts inside.
    I have no idea how to go about finding new and correct spring. I'm about to throw in the towel and get different brakes.
    Don't do that, those spring were a problem to keep straight back in the day, like I said get a pic of the parts on this site and maybe one of us old timers can see if we can tell if one of the spring is incorrect, also a good chance one of us has what you need to make these work.

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    Quote Originally Posted by sbsbiker View Post
    Don't do that, those spring were a problem to keep straight back in the day, like I said get a pic of the parts on this site and maybe one of us old timers can see if we can tell if one of the spring is incorrect, also a good chance one of us has what you need to make these work.
    I can see the plastic cover is shot so I tried a different cover from another XT brake I have and same result. Anyway, here are some pics.
    Again - thanks for your help.Brake help - please!-pic-1.jpgBrake help - please!-pic-2.jpg

  10. #10
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    I know that back then, often times the adjusting screw would slip past the spring. If you turned the screw all the way out, then readjusted, it would engage with the spring.

  11. #11
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    Quote Originally Posted by 202cycle View Post
    I know that back then, often times the adjusting screw would slip past the spring. If you turned the screw all the way out, then readjusted, it would engage with the spring.
    I suppose that could be it. I tried backing out the screw several times with no luck. I'm sure it my lack of knowledge on these. Just strange that the back brakes had no problem and I threw on another older XT brake and it works no problem.

  12. #12
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    If you lossen the bolt that holds it to the brake boss does it freely move. Many times in the olden days the boss was slightly too short so when the bolt was tightenned the brake would bind. Also take some sand paper and clean off the boss as they would rust up a bit, same with the inside of the brake. Then a light coat of grease prior to install.

  13. #13
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    Quote Originally Posted by AKamp View Post
    If you lossen the bolt that holds it to the brake boss does it freely move. Many times in the olden days the boss was slightly too short so when the bolt was tightenned the brake would bind. Also take some sand paper and clean off the boss as they would rust up a bit, same with the inside of the brake. Then a light coat of grease prior to install.
    Thank you for the tips. I did try loosening the bolt but that did not do the trick. It will spring back until you connect the cable.

  14. #14
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    Quote Originally Posted by bp101 View Post
    Thank you for the tips. I did try loosening the bolt but that did not do the trick. It will spring back until you connect the cable.
    If the arm springs back when the straddle cable is not connected, but does not when it is connected, it means that there is not enough spring tension on the arm. The cable is being pulled (likely by the spring in the brake lever) and is over-powering the spring in the brake arm. You need to increase the spring tension.

    - If your brake boss has multiple holes for the pin, use the one that gives the most tension.
    - Make sure that the spring is sitting in the holes that secure it on both ends.
    - Make sure that you're using the correct right/left spring in that arm.
    Each bicycle owned exponentially increases the probability that none is working correctly.

  15. #15
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    The pic that you show has the wrong spring in it. The spring that you show will unwind as the arm rotates towards the rim, you need the spring to wind as the brake is tensioned. The mounting hole is pretty grimy also, clean it up so it rotates freely.

  16. #16
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    Quote Originally Posted by laffeaux View Post
    If the arm springs back when the straddle cable is not connected, but does not when it is connected, it means that there is not enough spring tension on the arm. The cable is being pulled (likely by the spring in the brake lever) and is over-powering the spring in the brake arm. You need to increase the spring tension.

    - If your brake boss has multiple holes for the pin, use the one that gives the most tension.
    - Make sure that the spring is sitting in the holes that secure it on both ends.
    - Make sure that you're using the correct right/left spring in that arm.
    Whew - this is way tougher than I imagined. So ready to toss these itís not funny.

    Ok - if the spring is the wrong spring - why does it spring back without cable?
    Also - both brake and fork only have one hole for spring.
    I used another brake and spring looks to be the same and it works fine.

    I feel like Iím becoming a bother hear and donít want to wear out my welcome. When I originally posted this question I thought it was going to be an easy fix.

    Very perplexed and weary at this juncture. Pretty sure it would be easier to shoot the lock off my wallet and buy new brakes.

  17. #17
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    Quote Originally Posted by bp101 View Post
    Whew - this is way tougher than I imagined. So ready to toss these itís not funny.

    Ok - if the spring is the wrong spring - why does it spring back without cable?
    Also - both brake and fork only have one hole for spring.
    I used another brake and spring looks to be the same and it works fine.

    I feel like Iím becoming a bother hear and donít want to wear out my welcome. When I originally posted this question I thought it was going to be an easy fix.

    Very perplexed and weary at this juncture. Pretty sure it would be easier to shoot the lock off my wallet and buy new brakes.
    It's not a bother at all. It's how we learn and trust me, we've all been in the place you're at now.

    Incorrect spring is often the culprit. I've had M734 brakes missing that little washer with the 'cut' out of it that takes the alignment screw out of play. The plastic cover shouldn't make or break the functionality.

    Those brakes are looking pretty well used though. Is everything thoroughly cleaned and regreased? Might be worth getting a second set to pirate parts from.

    For us to help you trouble shoot, the more photos the better.
    -eric-

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  18. #18
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    Quote Originally Posted by Rumpfy View Post
    It's not a bother at all. It's how we learn and trust me, we've all been in the place you're at now.

    Incorrect spring is often the culprit. I've had M734 brakes missing that little washer with the 'cut' out of it that takes the alignment screw out of play. The plastic cover shouldn't make or break the functionality.

    Those brakes are looking pretty well used though. Is everything thoroughly cleaned and regreased? Might be worth getting a second set to pirate parts from.

    For us to help you trouble shoot, the more photos the better.
    Very good to know. I got these brakes in a trade and he is sending me another set of XT brakes so hopefully I can swap parts and make it work.

    As a side note - your website is amazing!

  19. #19
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    Quote Originally Posted by bp101 View Post
    As a side note - your website is amazing!
    Thanks man! Which reminds me, I have some updates to post.
    -eric-

    http://www.rumpfy.com
    Wanted: NDS Suntour XC Pro Microdrive 175mm Crank Arm.

  20. #20
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    Quote Originally Posted by bp101 View Post
    Also - both brake and fork only have one hole for spring.
    It's possible that the spring is distorted enough to not be functional on a frame with only a single hole for adjustment. Does either the other mounting point (front/rear) have multiple holes?

    I had a bike with single holes that even with the tension adjusted as high as possible did not have enough spring tension to work with a pair of Shimano brakes. I ended up using a set of brakes that do not require the use of the holes for tension adjustment (i.e. Dia Comp, Paul, Avid, etc.).

    In general brakes are one of the "less fun" things to work on, in my opinion. Some brakes are super awesome and easy to work on (Avid Tri Align) while others are less so. Shimano brakes are "in the middle" for me - not particularly difficult, but not nearly as easy as other designs. Spring tension adjustment on Shimano is really laking compared to many other options.

    Try taking a good spring (assuming you have one working pair on the bike) and using it on this arm to see if it works. If it does, you know it's the spring. If it does not, then you know that there is some other issue going on.
    Each bicycle owned exponentially increases the probability that none is working correctly.

  21. #21
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    Quote Originally Posted by AKamp View Post
    The pic that you show has the wrong spring in it. The spring that you show will unwind as the arm rotates towards the rim, you need the spring to wind as the brake is tensioned. The mounting hole is pretty grimy also, clean it up so it rotates freely.
    AKamp - I will never second guess you again. That was exactly the problem. The super cool guy I got these from sent me another set and that's when I discovered you were right. Wrong spring was the culprit all along. Popped it in - adjust the tension screw and I'm in business. I feel like a little kid at Christmas. A major thank you to all who helped. PROBLEM SOLVED!

  22. #22
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    We have probably all done it more then once. Glad it working better.

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