Results 1 to 6 of 6
  1. #1
    RoadBikeReview Member
    Reputation:
    Join Date
    May 2008
    Posts
    55

    Dura Ace 7900 Brake Caliper - Rear Pivot Bolt too small?

    I am installing the rear 7900 brake calipers on my 2006 Lemond Tete de Course and I think the rear pivot bolt used to install the caliper onto the frame is too short. The front caliper went in perfectly but the rear one is not. According to Shimano's website, the rear caliper's bolt is 1.5" but there is no way that is going to be long enough. It is #4 in the attached diagram link.

    http://techdocs.shimano.com/media/te...9830651588.pdf

    Am I doing something wrong? Are there different lengths available and I need to order a longer pivot bolt?

  2. #2
    wim
    wim is offline
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2005
    Posts
    10,452
    Just use a longer pivot bolt nut. Get one (any LBS) long enough so it engages at least six pivot bolt threads when it's tight. If you want a genuine DA 7900 nut, get one of the nuts listed for the front brake.

    /w
    Last edited by wim; 07-05-2009 at 05:04 AM.

  3. #3
    RoadBikeReview Member
    Reputation:
    Join Date
    Jul 2006
    Posts
    24
    Sorry Wim but a longer nut will not magically make more threads engage it. Longer nuts only prevent the bolt from bottoming out in case the bolt is too long.

  4. #4
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    10,126

    ???

    Quote Originally Posted by swifty
    Sorry Wim but a longer nut will not magically make more threads engage it. Longer nuts only prevent the bolt from bottoming out in case the bolt is too long.

    You're confused. A longer nut is indeed the solution to a frame with a thicker than normal brake mounting area. It's not often a problem with the rear brake, but frequently an issue at the front. Most forks come with an appropriately long nut, to mate with the standard length mounting stud.

    A brake mounting stud would never be 1.5 inches long. Perhaps 1.5cm.

  5. #5
    duh...
    Reputation: FatTireFred's Avatar
    Join Date
    Jan 2005
    Posts
    9,823
    Quote Originally Posted by swifty
    Sorry Wim but a longer nut will not magically make more threads engage it. Longer nuts only prevent the bolt from bottoming out in case the bolt is too long.


    that was true in the days of non-recessed nuts, but those days are long over...
    .


    Quote Originally Posted by mikagsd
    Fat tire Fred....you are the bike god of the universe and unless someone agrees with your reasoning they are just plain stupid

  6. #6
    RoadBikeReview Member
    Reputation:
    Join Date
    Jul 2006
    Posts
    24
    Oops, I apologise for the brain fart. You are right of course.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

INTERBIKE

Contest

Hot Deals See All Hot Deals >>

Interbike Featured Booths

Check out the hottest road bike products from these brands!



















See All Interbike Coverage - Click Here »


Latest RoadBike Articles


Latest Videos

RoadbikeReview on Facebook