Have I killed my frame with ti caliper bolts?- Mtbr.com
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  1. #1
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    Have I killed my frame with Loctite?

    While my Thunderbolt is the best bike I have ridden (and my most used) it's also a frameset that's had it's share of issues (some of them my fault).

    The latest seems to be delamination near the front hole of the rear brake mount. I noticed a crack in the paint and underneath the carbon is simply falling apart:

    Have I killed my frame with ti caliper bolts?-31128454_2048111115217960_1126122636_o.jpg

    I've got everything off for warranty but at the same time I'm wondering if it's user error again. I've used titanium M6 caliper bolts with a liberal amount of Loctite. They certaintly aren't working loose on long descents but... heat transfer may be the core issue. Anybody have an idea?
    Last edited by eric; 04-30-2018 at 10:26 AM. Reason: Changed title to reflect content of thread better

  2. #2
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    Titanium and stainless steel have almost identical thermal conductivity, so that shouldn't be a factor, and Ti has half the thermal expansion coefficient of stainless steel, so it shouldn't be a bolt issue.

    Thermal conductivity coefficient (cal/cm2/sec/C/cm)

    Titanium 0.041

    Stainless steel 0.039
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  3. #3
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    yeah was gonna say ti and stainless steel are nearly identical in the scheme of things related to heat transfer. ti is only a tiny bit better...negligible

    [if you used chro-mo bolts they are far better heat sinks]


    Material Thermal Conductivity
    (W/m oC)
    Admiralty (71 Cu - 28 Zn - 1 Sn) 111
    Aluminum 205 - 250
    Aluminum brass (76 Cu - 22 Zn - 2 Al) 100
    Brass (70 Cu - 30 Zn) 99
    Carbon Steel 45
    Carbon-moly (0.5 Mo) 43
    Chrome-moly steel (1 Cr - 0.5 Mo) 42
    Chrome-moly steel (2 1/4 Cr - 0.5 Mo) 38
    Chrome-moly steel (5 Cr - 0.5 Mo) 35
    Chrome-moly steel (12 Cr - 1 Mo) 28
    Copper 386
    Cupro-nickel (90 Cu - 10 Ni) 71
    Cupro-nickel (70 Cu - 30 Ni) 29
    Inconel 19
    Lead 35
    Monel (67 Ni - 30 Cu - 1.4 Fe) 26
    Nickel 62
    Polypropylene 0.1 - 0.22
    Red Brass (85 Cu - 15 Zn) 159
    Stainless Steel, type 316 (17 Cr - 12 Ni - 2 Mo) 16
    Stainless Steel, type 304 (18 Cr - 8 Ni) 16
    Titanium 19


    IMHO this is 100% warranty. the parts that the caliper bolts onto must be durable enough so -any caliper- will work, no matter how hot it gets*. it is
    a critical safety device (the brake mount) and yours is simply bad and they
    must warranty that.

    *if a bicycle caliper from a respectable brand, and it gets hot from bombing descents, it must stand up to that, as well as the side load and torque from braking.
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

  4. #4
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    Thanks for the responses. The distributor will have a look on Sunday (festival out here) - I'm sure things will be sorted. RMB has taken very good care of me with this frame

  5. #5
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    I wonder if loctite was too much, and 'carrier creep' ate away at the matrix ?
    loctite has a volatile carrier [which can weep as a clear fluid] apart from the colored goo.
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

  6. #6
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    Quote Originally Posted by 127.0.0.1 View Post
    I wonder if loctite was too much, and 'carrier creep' ate away at the matrix ?
    loctite has a volatile carrier [which can weep as a clear fluid] apart from the colored goo.
    Yes, good one. It could very well be - I've seen people damage paint with too much Loctite, so this might very well be a contributor.

  7. #7
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    I'll bet it's the Loctite. Loctite can be very destructive to plastic. I've ruined plastic parts using Loctite even when the Loctite was not in direct contact with the plastic.

    If you need to use a thread lock in or around plastic use something like this. Vibra-TITE 213 VC-3 Threadmate Threadlocker. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

  8. #8
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    Quote Originally Posted by Loch View Post
    I'll bet it's the Loctite. Loctite can be very destructive to plastic. I've ruined plastic parts using Loctite even when the Loctite was not in direct contact with the plastic.

    If you need to use a thread lock in or around plastic use something like this. Vibra-TITE 213 VC-3 Threadmate Threadlocker. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    or dab the bolts and then let the loctite dry completely before screwing in,
    this way no carrier creep. it's still provide some type of locking friction
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

  9. #9
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    Locktite man ALL the way I'm guessing. It should only be used on metal to metal unless you are SURE. I see this kind of stuff happen in aerospace engineering with newer engineers not checking material compatibility.

    Damage to Plastic Components from Loctite

    I also think it can depend on which loctite you are using too as I think some have stuff like acetone etc.

  10. #10
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    Do horst link brake bosses see more forces? I ask because I seem to see more horst brake bosses fatique comparatively.
    I was of the understanding that todays resins and epoxies are far more stable to solvents, heat, glue etc. than years back? Several years back locktite absolutely made plastic and carbon brittle. I don't experience that these days, at least in the RC world. With that said most post style brake bosses on carbon frames have metal inserts.
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  11. #11
    RAKC Industries
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    Could very well see loctite doing this.

    First thing never go liberal with loctite. A little goes a long way. But its about getti f the goo on there and not mostly the carrier fluid. In contact with resin, carbon fiber, plastic, have to let it dry first.

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  12. #12
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    Unfortunately I haven't been able to get any reliable info from the interwebs apart from people using 243 on carbon RC helicopter parts (without problems). Supposedly the epoxy used is hardly affected by anything, even acetone. Hmmmmmmm........

  13. #13
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    Quote Originally Posted by eric View Post
    Unfortunately I haven't been able to get any reliable info from the interwebs apart from people using 243 on carbon RC helicopter parts (without problems). Supposedly the epoxy used is hardly affected by anything, even acetone. Hmmmmmmm........
    That's been my experience. 10-12 years ago was a different story.
    It is no measure of health to be well adjusted to a profoundly sick society.

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