Has anyone succeeded in taking out a broken bolt from a thumbie mount?

[Tootyred]

Left hand drill bit.....

 

[Tootyred]

Trying to remove a steel bolt from an alluminium thread is best done in one bit. If you try to break up the bolt by drilling it multiple times with a conventional drill bit you are likely to force the broken bit further in or damage the softer alluminium. Also, as the hole is blind, when it bottoms out (or not if its that stuck), you will just rip the tread out as the bolt trys to go into the thread and cant.

Left hand bit will grab the bolt and spin it in the direction to remove it. Most times, just the grip of the bit on the bolt will be enough to remove it, without multiple drillings.

If the thread is knackered after, just pop a helicoil in the mount. Done this exact job many times on various thumbies and never had a helicoil fail.

Good luck.

 

[Prodigal Son]

Yup: left hand drill. That´s how i will fight this thing today. Let´s see how it goes. I am not too optimistic about it but i will give it a try. Otherwise it will be zip tied it to the brake lever till i find a replacement.

 

[donk]

Drill a small hole from the backside, slide in an allen key and apply pressure from the backside to the bolt as you turn it, the pressure from the backside can be enough for the threads to grab and work the bolt out.

If the threads are totally gone and you get the bolt out, drill through and install a nut and bolt. This is the fix on mine, going strong for 25 years.

 

[Tootyred]

There's no head on the bolt....it snapped. Also if you drill through from the other side, you will damage the shifter mounting perch.....xt perches are already flimsy enough that's why they crack at the seam as soon as you flip the bike to change a tyre!

 

[donk]

OOPS, missed that the head had broken off. That is a different can of worms.

 

[Prodigal Son]

The left hand drilling went all wrong: not only it shattered the bolt remains, it also ate the shoe where the allen bolt should sit while forceed open the tabs.. The guy with the drill called quits. Being the stubborn type; i took a bolt w/ a sharp end and began tapping over the missing bolt and bringing the "ears" back to place using several nuts as leverage. I had a hunch the broken bolt would be bad duraluminum and a sharp steel bolt could tap inside it. Well, it did. Mind you; it´s far from ideal. There is no space for a proper length bolt and the one inside is very short but so far the mount is back to it´s job.
Now i can look patiently for a pair of suntours.