MegaSack DRAW - This year's winner is user - rgwb
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Bolt that snapped wasn't a Thomson - unknown provenance so may have been low spec BUT
the lower bolt on this has always been strange - it felt “sticky” and made a cracking sound when tightened/loosened. Never felt “smooth”.
I use a torque wrench at home but obviously if the bars get turned in a crash out on the trail that’s not an option. Forks were off the bike last week so I cleaned up the stem and bolts with white spirit and replaced the lower bolt, which was slightly rounded off, with one from my stock. Bolts well greased and torqued with a torque wrench.
Headset came loose at the weekend and when I tried to loosen the lower bolt it made a familiar cracking sound and the bolt snapped.
Could this be a faulty stem - I’m wondering if the threads on the two halves of the steerer clamp are slightly out of alignment - it feels like something is causing that bolt to bind or be under an unusual stress? I’ve never had this happen on another stem (and I’ve had a lot of Thomson over the years).
I had a similar thing, lower steerer bolt always felt "tight" in the threads and was difficult to torque correctly, then undoing it one day it just snapped. I ended up using a dremel to cut the bolt at the slot in the stem, but couldn't get the stubs out so ditched the Thompson and now probably wouldn't buy another.
the lower bolt on this has always been strange – it felt “sticky” and made a cracking sound when tightened/loosened. Never felt “smooth”.
Not very helpful advice now it's snapped, but if I come across a tight thread like this, I'll just run a tap through it to clean up the threads. It's amazing how often you'll find rough or unfinished threads on all sorts of things (even on expensive bikes) and a set of taps and dies are a great investment for such situations.
For the snapped bolt, you could try a reverse-thread bolt extractor to get it out. Might not have much luck if it's very tight in the threads, but got to be worth a go to save the stem and there's nothing to be lost.
Sprung Suspension at FoD pushed the broken bolt out from the other side with a screwdriver (Great service - K sends her thanks) and put a new bolt in. I'm just wondering if it's going to go again.
Thomson are doing the usual 'fill in a form' potential warranty that they'll likely refuse because I've no idea where I'd find proof of purchase and it will be outside their warranty anyway. Pretty sure it was sat new and unused for a year or two before it went on k's bike.