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Fubar'd rotor bolt - creativity needed!

tom_funtom_fun Posts: 124
edited September 2010 in MTB workshop & tech
Hi there, I am replacing my 160mm front rotor disk for a 185mm but I have a problem. When I was removing the rotor bolts, one of them was too tight and when I was trying to unscrew it, the bolt has worn away on the inside so the allen key just turns and I cant undo the bolt :cry:

Any creative ideas out there to undo it? my best thought was to try and be a bit delicate with an angle grinder and try and wear down 2 sides of the bolt so i can get a pair of pliars on it

all help appreciated!


  • weeksy59weeksy59 Posts: 2,606
    couple of options.

    1. Knock a larger Torx into it,e.g next size up.
    2. As above, then use an impact driver to get it freed up.
    3. Get some plus-gas in there to help release it
    4. using hack-saw cut a flat scredriver slot into it.

    5. Last resort... get a drill out.
  • Are you sure it's an allen as opposed to a torx t25?

    Your idea sounds good. Try and make some purchase on the bolt head. Undo all the other and see if a twist and wiggle of the disk works.

    All else fails just whip the head off with a drill then move to an angle grinder - that can get maessy.
  • shm_ukshm_uk Posts: 683
    In the past, I have used a file to create flat spots on two opposing sides of the bolt head, thus enabling me to use a small spanner to undo the bolt.
  • shm_ukshm_uk Posts: 683
    Or use a hack-saw to cut a slot in the bolt head, then use a flat-head screwdriver to undo the bolt (you may need to use a pair of pliers on the screwdriver shaft to generate sufficient turning force).
  • chedabobchedabob Posts: 1,133
    If you've got another set of allen keys, try them. I've got 3 sets and they're all slightly different sizes.

    Try a thick elastic band too. Place that on the head and then use the allen key as normal.
  • SalsaSalsa Posts: 753
    Try the screwdriver first, if that doesn't work just angle grind the bolt head off & remove the rotor, grab the rest of the bolt with pliers/mole grips & turn it out.
  • tom_funtom_fun Posts: 124
    thanks for the ideas folks, used a grinder as in my original idea, did the trick in 2 mins.

    panic over :lol:
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