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#1 Torque wrench accuracy
Posted: Mon Dec 04, 2023 7:05 pm
by tim wood
I’ve had my torque wrench for many a year. It’s well used ( not really abused!)
It’s one of the basic type where the setting is achieved by twisting a marked barrel and pulling until it clicks.
I don’t really know how accurate it is. I know that this can be tested but that seems a faff and probably expensive. Does anyone have experience of these ? Do they go out of calibration?
Tim
#2 Re: Torque wrench accuracy
Posted: Mon Dec 04, 2023 8:32 pm
by rfs1957
Hi Tim,
My approach would be to do nothing.
I have four, for different ranges, and some of them are 25 years old ; but they’re mechanical, and - contrary to some metallurgical misconceptions - steel does not go « off ».
I don’t believe there's anything on the Jag that is super critical, and as there are almost no torque figures given for so many of the fasteners that would be littered with specified torques on a modern car, my feeling is that the design was meant to fend for itself in the field.
And so it has proved.
An easy way to allay any fears you have for, say, head bolt torques, is to test your wrench against someone else’s - you can face one off against the other, as it were.
Cheaper than a test certificate anyway

#3 Re: Torque wrench accuracy
Posted: Mon Dec 04, 2023 9:24 pm
by mgcjag
#4 Re: Torque wrench accuracy
Posted: Tue Dec 05, 2023 8:53 am
by chrisfell
Important advice in the above that I always follow - untension the wrench when finished.
I occasionally check the calibration using a spring balance pulling on the handle while the square drive is anchored in a vice. Simple and effective.
#5 Re: Torque wrench accuracy
Posted: Tue Dec 05, 2023 9:06 am
by tim wood
Thanks guys,
I’m going to have a play with it later today. Will let you know how I get on.
Tim
#6 Re: Torque wrench accuracy
Posted: Tue Dec 05, 2023 12:17 pm
by Series1 Stu
chrisfell wrote: ↑Tue Dec 05, 2023 8:53 am
I occasionally check the calibration using a spring balance pulling on the handle..........
Presumably the spring balance is suitably calibrated?

#7 Re: Torque wrench accuracy
Posted: Tue Dec 05, 2023 5:29 pm
by bitsobrits
Touche
#8 Re: Torque wrench accuracy
Posted: Wed Dec 06, 2023 8:36 am
by chrisfell
"Presumably the spring balance is suitably calibrated"
Of course, by the 1kg weight I'd previously suspended from it.
And that 1kg weight was calibrated on the kitchen scales.
And the kitchen scales were calibrated using a 1 litre jug of water.
And the jug of water was calibrated by suspending it from the torque wrench at precisely 500mm from the centre of the 1/2" square drive, winding the tension down until it clicked.
Then with reference to the time of day, the atmospheric conditions, basic trigonometry adjusted by Euler's constant and the number I first thought of, I hoped that ateast one of the measurements was accurate.
#9 Re: Torque wrench accuracy
Posted: Wed Dec 06, 2023 4:37 pm
by Series1 Stu
#10 Re: Torque wrench accuracy
Posted: Sat Dec 09, 2023 7:37 pm
by Fspp369
Hi PM me I’ve got the bit of kit I think you need.
Peter.

#11 Re: Torque wrench accuracy
Posted: Sat Dec 09, 2023 7:40 pm
by mgcjag
Don't be shy....share what it is

#12 Re: Torque wrench accuracy
Posted: Sat Jan 06, 2024 4:24 pm
by tim wood
Followed a few you tube videos on this. Checking calibration seems simple using weights at certain lengths along the shaft.
I reckon that mine is ok