Hi! I accidentally used an aluminium bolt when test-mounting a rear rack, and when I tried to unscrew it, the bolt sheared off. I only had the rack on for a few minutes, so I don’t think there’s any corrosion inside.
I asked my dad to help and he tried drilling it out and doing some other things, but now it looks like this (see photo). I don’t know what to do next.
It’s been like this for 2 days now. The frame is aluminium.
Does anyone know what I can do, and if it’s even possible to fix? Thamks in advance!
by Swimming_Evening_876
8 Comments
Might have overdrilled it, but the general advice would be a screw extractor
How does it look from the other side?
If there are some threads left showing you could go at it with a 5mm tap from that side. Go slowly and keep it lubed. Back it up frequently.
Carefully finish drilling this out, use a button head bolt from the inside out and use a tylox nut on the outside.
You could try tapping it as-is. Use lots of tapping fluid and a tapered tap. It’ll either clear out the old bits and leave you with fresh threads or it’ll indicate that the hole is now drilled too large. If too large just use a nut and bolt right through the frame to mount stuff. Don’t drill it any larger.
if any threads on the back side to ~~bike~~ *bite.*.. id try a brand new tap. slow and easy, a little bite of 1/8th-1/16th turn at a time then back out, to clear any chips and clean… and and with lube.
oie. best of luck.
Forgot to mention but the part that is stuck is max 5-6mm long
You are close to a point where you could damage the frame threads, at some point you will start to engage the frame threads.
Try to drill all the way through the screw and find an easy out that fits without engaging the frame.
You could try to find a screwdriver that press fits in the hole, grind or file a slight sharp edge to the screwdriver so that it bites into the screw.
Lube the area from both sides with a couple drops of transmission fluid mixed with a drop of paint thinner or some other penetrating fluid, PB or whatever you have.
If all else fails you can gently file as much screw as possible and pick the remaining material out of the frame thread with something like a dental pick or o-ring pick.
Be calm and patient, you got this.
For the benefit of others in the future, once the bolt is sheared it has no preload and is usually easy to back off if you can manage to file a slot in it for a screw driver or use a small, sharp punch and small hammer near the edge of the screw to impart a counter clockwise impact.
Or for drilling out, a left-handed drill bit will often back the screw out well before you get through. Or in this case, a normal drill bit from the back might have worked.