Torque calibration

Has anyone knowingly had a torque wrench go out of calibration? I ask because just did a bolt check on my new bike after one ride ( mainly just to get the know the bike and work it out) but snapped a bolt heat off. Luckily easily extracted and will go to the fixing supplier today.
I’ve for a mariposa I received as a gift about 8years ago. I’ve looked at calibration which appears to be about £40. So I’ve bought a cheap one from crc to cross check it with.

How accurate is the “cheap one”?

https://www.engineeringtoolbox.com/torque-lubrication-effects-d_1693.html

Torque settings depend on lubrication used or dry.
https://www.molyslip.co.uk/copaslip/

I would hope the bolt and requirement to were to spec as it was straight from the factory. They were dry as it happens.

Also aware of this as an old timer once recounted a story to me that airbus once spent thousands working out why bolts were snapping in flight. It was eventually traced to some one adding a drop of oil to the bolts to “help them go in”. But tbh they still shouldn’t snap you have to go way over

😂true that. But it’s just a double check

Was it an alloy suspension pivot bolt?

If so some manufacturers are pretty snappy on a brand new bike.

More likely it came from the shop/factory over torqued …

But more than that … Did you back it off first ?

Torque settings depend on lubrication used or dry.

Does that include threadlock ?

Probably a duff bolt, no?

Yes, threadlock affects torque settings also

I hear more stories of people snapping fixings when using a torque wrench than when using a normal spanner/socket whatever.

Apart from silly SRAM cranksets are there any other bolts on a bike that need torqueing up so much that you run the risk of snapping heads off? Most stem (and the like) are down at 4-5Mn. Even pivot bolts are normally around 15-20mn max.

Apart from silly SRAM cranksets are there any other bolts on a bike that need torqueing up so much that you run the risk of snapping heads off? Most stem (and the like) are down at 4-5Mn. Even pivot bolts are normally around 15-20mn max.

i would have expected that the majority of snapped bolts on pivots are due to the lightweight bolts used only just being suitable.

anything more than 15nm is significantly more than tight with an allen key and there is increased risk with the alloy bolts imo. However if your checking them and they have threadlock. If they move you need to take them out, clean them and reinstall using threadlock or it wont be right.

Was it an alloy suspension pivot bolt?

If so some manufacturers are pretty snappy on a brand new bike.

This. Just look at the bolts produced aftermarket, eg unite etc. They aren’t just cos folk like silly colours. Well they do like silly colours, but a snapped bolt gives the opportunity for silly colours.

You can check the calibration of your torque wrench yourself using an accurate luggage scale and some arithmetic. Videos on youtube. I checked all of mine using this method. All of the Norbar wrenches were within plus or minus 3% The older Britool wrench that I’ve had from new was over torquing by 15%.