Shimano 105 Chainring bolts
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tackleberry
Posts: 82
in Workshop
When re-attaching my 105 4-bolt chainring, I appear to have cross threaded the bolts so that the inside thread of the integral bolt is damaged and even using new "male' bolts has no remedied the problem. I expect the chainring is a write-off however is it possible to re-do the thread? Guessing this is a (very) longshot - have a replacement on order, y'know - just in case.
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Comments
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Any chance of just using a normal tap in there or is it all too tight?.
The camera down the willy isn't anything like as bad as it sounds.
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I believe the thread is M8x .75 You can get a bottoming tap that thread but if you have removed or pulled the thread out of place that may not help.
A thread insert would mean drilling out bigger and I don't think there is much meat around the hole for that to work well. Finding an M8 x .75 insert is likely to be a bit of a mission. You could use a normal m8 x 1.0 'metric fine' insert but then you would have a non-standard bolt to find.
I think given the outlay you'd need to make for any of those options and the probability of the fix being poor, replacing the chainring is probably the best option. Check the prices too - often a complete chainset is not much more than just the rings.0 -
I would bin it as any fix is pretty shady considering where it is and the possibilities of what could happen if it fails .0