Help! Rounded off bolt on Hollowtech 2 cranks.
neil_sheehan2000
Posts: 529
I'm fairly sure this has been asked before but I couldn't find it with the Search function- sorry.
Anyway, I've managed to round off one of the bolts that holds the crank arm on on my Hollowtech 2 cranks (the non-drive side arm that clamps on to the bottom bracket). Took it to the LBS who told me to take it to an engineer. I live with an engineer, and he seems to be of the opinion that the bolt is too small to guarentee that it can be drilled out with those reverse-thread things without damaging the crank arm. Tried to stick an allen key in there with Araldyte (sp?) so I could just unscrew it and that didn't work.
Basically, I need to ride my bike for Pedal For Scotland this Sunday. I was thinking maybe if I cut the bolt in half (there's a slot down the middle of the crank arm that a hacksaw blade could fit down) I would at least be able to get the cranks off and fit my spare set, leaving me time to worry about the rounded off bolt at my leisure. I'm thinking that with no strain left on the bolt I could at least get the top half of it out using just an allen key. Is this a bad idea? Would it make it even less likely that I would be able to get the bottom half of the bolt out? If this is a bad idea, what should I do instead?
Any help gladly appreciated as I'm running out of time and ideas.
Cheers.
Anyway, I've managed to round off one of the bolts that holds the crank arm on on my Hollowtech 2 cranks (the non-drive side arm that clamps on to the bottom bracket). Took it to the LBS who told me to take it to an engineer. I live with an engineer, and he seems to be of the opinion that the bolt is too small to guarentee that it can be drilled out with those reverse-thread things without damaging the crank arm. Tried to stick an allen key in there with Araldyte (sp?) so I could just unscrew it and that didn't work.
Basically, I need to ride my bike for Pedal For Scotland this Sunday. I was thinking maybe if I cut the bolt in half (there's a slot down the middle of the crank arm that a hacksaw blade could fit down) I would at least be able to get the cranks off and fit my spare set, leaving me time to worry about the rounded off bolt at my leisure. I'm thinking that with no strain left on the bolt I could at least get the top half of it out using just an allen key. Is this a bad idea? Would it make it even less likely that I would be able to get the bottom half of the bolt out? If this is a bad idea, what should I do instead?
Any help gladly appreciated as I'm running out of time and ideas.
Cheers.
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Comments
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Ive used a bolt extractor on a brake lever clamp bolt(4mm allen key) without doing any damage, you just need the correct size, id say it would be tight enough, your only supposed to do them to 15nm max which is well below what the average person could tighten them to by hand.
http://www.machinemart.co.uk/shop/produ ... extractors0 -
maybe you could use a torque bit slightly larger than the allen head, and hammer that into the head of the allen bolt0
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Have you put the other one in and tightened it up a bit more, should loosen off the stuck one a bit and you might be able to get it out with a torx bit0
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dont forget that the other end of the bolt is also accessable.
but other bolt in (or a new one if that is also looking poor) norrmally works."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0
