Sheared brake boss bolt

tiny_pens Posts: 293
edited October 2011 in The workshop
I loaned my beer bike to a friend and long story short it came back with a few bits of damage.
Chief of which is one of the brake boss bolts (thing that holds the v-brake onto the frame) has sheared off level with the top of the boss. (hence can't use a dremel to cut a slot to get the flathead screwdriver on it.

It has been soaked in penetrating oil.

As its a folding bike frame the seat stay is very close and makes it difficult to get a drill in there to drill the bolt out. So my left handed drill bits aren't doing so well at the moment as I can't get a straight line as any bits I have small enough are too short to reach between the stays - same problem with my stud extractor.

My next port of call will be to try the heat lamp to free it but after that I'm a bit short of ideas. On the subject of heat - any ideas what I might use that is directional enough to cool the bolt without cooling the boss?


  • Gussio
    Gussio Posts: 2,452
    You *might* be able to get a straight enough drill line using a cabinet making drill, designed to drill holes in rightangled corners. Don't know how much they cost though. LBS might be able to help out.

    Sounds a pain. Good luck...
  • davewalsh
    davewalsh Posts: 587
    You may be able to unscrew the bolt by drifting it out with a centre punch on the outside of what is left of the bolt shank. Any chance of a pic so we can have a better look ?
  • tiny_pens
    tiny_pens Posts: 293
    Good idea about the centre punch. Will give that a try

    The frame is steel so my ultimate idea is to chop off the boss and weld a new one on. I imagine this is going to work out a lot more complicated than it first seems (just checked and it looks possible to get something from ebay that might fit) but as I don't weld (yet) it could be an interesting learning experience