I really ought to know the answer to this question but I’ll ask it all the same. Ever since I messed about with cars as a lad I have always thought that these two values were tolerances. It didn’t matter then becasue I coudn’t afford a torque wrench. But I am probably wrong. It occurs to me that there are other posibilities such as;
Someone will probably correct me but where there are two figures given it’s , as you said, the tolerance. The correct torque setting is between these figures.
And I was taught that the figure was for a “dry” thread: i.e. no grease.
Yep, the 2 figures are the tolerance and that’s dry with no lube on the threads.
There’s a good sheet and settings here, http://www.leytonfasteners.co.uk/pdfs/TorqueValueGuide.pdf but most of us learn common sizes using handtools on a bike when we’re young don’t we. As the man said, tighten it til it strips then back off a quarter
Use the pneumatic impact wrench on the highest setting so no one without a 6 foot breaker bar will have a hope in hells chance of undoing them.
Set the torque wrench to the correct setting and go round the wheel nuts “clicking” the torque wrench on each nut (torque wrench set about 110Nm, wheel nuts done up to 200Nm in operation 1).
Any wheel studs/bolts snapped off to be superglued back on before customer notices.
It is a very hard thing to teach Alan, when to stop with different metals and nuts and bolts, you either get it over time or not, i am just lucky i guess
So the general concensus is that the two figures are tolerance after all.
It’s just that the difference between high and low setting varies between 6% and 30% on some figures. Why give two settings why not just quote a single figure to set to, I still think there is a bit more to this question. Thanks to all for your input anyway.
The minimum is the least required to do the job (stay done up, and hold the bits together firmly enough). The maximum is the most the bolt, or component, can take before breakage becomes more likely (although you would have to exceed it a fair bit normally, if everything is in good nick)
I generally use a torque qrench set to the middle of the range (this allows for inaccuracy of my tool). However, I only really bother using a wrench on suspension and brake parts or head bolts, where mistakes matter most. Normally, you can tell pretty easily what kind of torque it’ll need and can break it down into ‘nip it up’, ‘quite tight’, ‘very tight’ and ‘stand on it’.
With a bit of experience you can tell what torque you need from a few clues. Stainless is weak, aluminium so-so and steel quite hard. The size and type of the bolts is a huge clue too. Also whether you expect the joint to take any kind of serious load, or if it’s just stopping a component falling off.
the last time i used one was for wheel bearings i think
