Thread: I bought a torque wrench

Originally Posted by DAMINK

Decided to google it.

"From tests, it is known that approximately 50% of the tightening torque is dissipated in overcoming friction under the bolt head or the nut face (whichever is the face that is rotated). Typically only 10% to 15% of the overall torque is actually used to tighten the bolt, the rest is used to overcome friction in the threads and on the contact face that is being rotated (nut face or bolt head)."

Source http://www.boltscience.com/pages/nutorbolttightening.htm

Yep. Which is why the condition of the threads and mating surfaces is so important.

Originally Posted by DAMINK

Putting my year 9 education to the test i tell ya.

Every day’s a school day.

The more surface area for a nut/bolt to clamp down on the more friction it will generate when tightening. The differences in such small applications such as a wheel nut would be bugger all however. Certainly makes a big difference when you start doing up bigger stuff with hydraulic powered drivers. Overall "torquing" a bolt by turning force is not all that accurate (especially with the bigger stuff), measuring bolt stretch (some con rod bolts are measured this way) or things like hydraulic stretching (really limited to industrial applications) are far more accurate. Hydraulic stretching bolts make for easier undoing as well

Originally Posted by shanegtr

The more surface area for a nut/bolt to clamp down on the more friction it will generate when tightening. The differences in such small applications such as a wheel nut would be bugger all however. Certainly makes a big difference when you start doing up bigger stuff with hydraulic powered drivers. Overall "torquing" a bolt by turning force is not all that accurate (especially with the bigger stuff), measuring bolt stretch (some con rod bolts are measured this way) or things like hydraulic stretching (really limited to industrial applications) are far more accurate. Hydraulic stretching bolts make for easier undoing as well

A bigger nut will generate more friction due to the larger bolt and thread, not the area it is clamping down on. A larger bolt is stronger and therefore you can apply a larger axial force to it - and need to in order to tension it correctly. This creates a larger normal force between the mating surfaces. Again, it is this force not the surface area which determines the amount of friction.

And yes, measuring stretch is the only really accurate way to measure the tension in a bolt. It is, in the end, what you are trying to achieve.

Cheers,
Jon

Originally Posted by DAMINK

Like these?



If so i used to own one of those and loved the thing. Think i loaned that to a mate and never got it back.

Wow, do you realise how bloody old that one in the photo is?

It's labelled Sidchrome but is actually a Ritch. I have one identical except the plate is black, not Sidchrome red and when last checked for calibration was spot on.

Oh, and it dates back to the 1950's I believe.
Dear old dad bought it 2nd hand in the late 50's/early 60's.

Originally Posted by jon3950

A bigger nut will generate more friction due to the larger bolt and thread, not the area it is clamping down on. A larger bolt is stronger and therefore you can apply a larger axial force to it - and need to in order to tension it correctly. This creates a larger normal force between the mating surfaces. Again, it is this force not the surface area which determines the amount of friction.

And yes, measuring stretch is the only really accurate way to measure the tension in a bolt. It is, in the end, what you are trying to achieve.

Cheers,
Jon

Originally Posted by rick130

Wow, do you realise how bloody old that one in the photo is?

It's labelled Sidchrome but is actually a Ritch. I have one identical except the plate is black, not Sidchrome red and when last checked for calibration was spot on.

Oh, and it dates back to the 1950's I believe.
Dear old dad bought it 2nd hand in the late 50's/early 60's.

I do mate. I also had a black one haha or it might have just been old and no paint left. My mates old man gave it to me along with heaps of other stuff. Rest his sole. Old bugger drove himself to hospital and complained of a hearty, they said your fat, he walked out and died on the damn door step of hospital with DVT. Tough old bastard. I wish i still had that Tension device! Here is an old sanding block thing he gave me also lol. Just because its in my shed being used currently.

20180802_191639[1].jpg

Sooo got nothing to do with tension wrenches but hey, its what i do seemingly.

4 reasons to use a torque wrench on wheel nuts.
Nuts don't come loose, like they did on my series 3, first time I had a wheel off.
Studs don't break due to over stretching.
Can get rid of mysterious vibrations in front end, due to the wheel being warped by odd tensions.
Don't damage the wheels due to too much tension on area where nut seats.

cheers

fredd
that's not an oil leak, it is just sweat from all that horsepower