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vanishing fender mount plug screws seized

macleod113macleod113 Posts: 560
edited February 2014 in Workshop
Hi All,

i have recently ditched my crud road racers due to excessive rubbing and have bought some bontrager approved ones.
i have also purchased the hidden fender mount screws (£15 for 4! blimey) but last night i was unable to remove 3 of the 4 original grub screws the bike had installed (Trek 2.1 2013). its a 2.5mm allen screw but the 3 that are stuck wont budge. i have tried spray lube but they wont shift. i have tried different allen keys also with no joy (long l shaped one and my multitool one). with too much force they feel like i am rounding the holes off.
does anyone have any experience with shifting these stubborn boggas?

any help much appreciated
Cube Cross 2016
Willier GTR 2014


  • oxomanoxoman Posts: 9,733
    Sometimes if you try to tighten them slightly it will break the bond and allow you to undo. However doesn't always works and you might have to drill out, not for the faint hearted or caggy handed either. Might be worth letting your LBS take the pain.
    Too many bikes according to Mrs O.
  • Tyr soaking them well with PlusGas for a good while and the try removing with either a larger allen key or torx key for better grip. If that fails I would try cutting a slot for a flat head screwdriver before I would contempalte drilling them out.

    Never tried PlusGas myself but several really knowligable people on here say its the best for anything that's siezed. Good luck
  • Thank you for the tips. will try again this evening.

    i've never heard of PlusGas so will be googling that next :-)
    Cube Cross 2016
    Willier GTR 2014
  • balls! tried additional lube and tightening the bolts last night. sadly i must have rounded the screws completely as now it feels like chucking a chipolatta down the mersey tunnel!
    looks like a trip to the LBS to get them drilled out or maybe i can use the o ring mounts from my cruds. will look ugly as sin i reckon but could work out just fine!
    Cube Cross 2016
    Willier GTR 2014
  • keef66keef66 Posts: 13,123
    Once they are rounded your options are

    a) try tapping in a slightly larger Torx bit

    b) very careful drilling and use a screw / stud extractor

    c) admit defeat and take to LBS

    If you don't already have the tools, c may well be cheaper than a or b.
  • arlowoodarlowood Posts: 2,527
    If all else fails take a look at what this guy did to solve the perennial mudguard problem on bikes with no eyelets.


    Might be a better option than the risk of damaging forks/frame when drilling out the grub screws.
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