Preventing slipping disc rotors

junglist_matty
junglist_matty Posts: 1,731
edited April 2013 in MTB workshop & tech
I put new rotors on my MTB, tightened up the 6 (brand new with the anti slip coating) torx bolts and slotted the wheels back in.... After a few miles of riding, the rotors seem to work themselves loose. The best way to describe it is to apply the brake so it is clamped on the rotor, then rock the bike forward and back, you can notice that the rotor is "slipping", in other words, it's as if the bolts are not tight enough, but tighten them up and a few miles later, the same issue.

Any ideas to prevent this so the rotors are rock solid on the hubs?

Comments

  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Are you sure it is the rotor bolt coming loose?
  • nicklouse
    nicklouse Posts: 50,675
    pads rocking in the caliper.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • junglist_matty
    junglist_matty Posts: 1,731
    Nope, definitely the rotor slipping...

    Hubs are factory wheels - Mavic CrossRide 29

    Hubs, Rotors, Bolts all brand new
  • nicklouse
    nicklouse Posts: 50,675
    poor undersize bolts then.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • junglist_matty
    junglist_matty Posts: 1,731
    These are the bolts I'm using:

    http://www.chainreactioncycles.com/Mode ... elID=69619
  • RobJ20
    RobJ20 Posts: 48
    Put some higher strength thread lock on. I have never had this issue though, its usually the pads moving a bit inside the caliper.
  • nicklouse
    nicklouse Posts: 50,675
    junglist_matty wrote:
    These are the bolts I'm using:

    http://www.chainreactioncycles.com/Mode ... elID=69619
    just as i thought poor. no shoulder.

    also alloy so dont do them tight as you will strip something. bolt or hub.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • junglist_matty
    junglist_matty Posts: 1,731
    nicklouse wrote:
    junglist_matty wrote:
    These are the bolts I'm using:

    http://www.chainreactioncycles.com/Mode ... elID=69619
    just as i thought poor. no shoulder.

    also alloy so dont do them tight as you will strip something. bolt or hub.

    Yep, they're not screwed in "incredible hulk" style, I try not to over-tighten bolts; I'm thinking of trying some Ti bolts
  • The Rookie
    The Rookie Posts: 27,812
    Just use steel! Ti is better than alloy, but other than weight inferior to steel.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • jairaj
    jairaj Posts: 3,009
    nicklouse wrote:
    ... just as i thought poor. no shoulder....

    Can you explain what a shoulder is and how they are beneficial?
  • nicklouse
    nicklouse Posts: 50,675
    jairaj wrote:
    nicklouse wrote:
    ... just as i thought poor. no shoulder....

    Can you explain what a shoulder is and how they are beneficial?
    threads all the way to the head mean the bolt where the rotor is held is not the correct size. this can be more pronounced on some hubs with some discs as the thread lines up to give worst case situation.

    have a look at some OE bolts. most have a shoulder on them so the discs are held inplace without needing massive clamping forces.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown

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