A forum for owners of Yamaha TTR250 trail and enduro bikes!

Broken bolts or chewed up screw heads can often be removed using left hand spiral drill bits which back the problem stud or bolt out its hole without damaging the thread. Screw extractors are brittle and can snap. Left hand spiral bits drill in an anti-clockwise direction and can release the pressure on the thread when compared to standard right hand spiral bits that will continue to tighten the bolts in its thread. Or so says the advertising blurb.

But today it worked! I used a LH drill bit on a caliper pin where the hex had rounded and it worked a treat.