Engineer's. / Experts

flattop1

Dawg 89
Curiosity killed the cat.
Is this going to be a one to one , or is there some kind of mechanical advantage here ?
Seems to be a lever in there .
 

Attachments

flattop1

Dawg 89
Reminds me of an article by Outrider about torque wrench's . It was quite enlightening.
I did think if the angle got too far off it would not
Function properly.
 

manyfunnies

New member
Reminds me of an article by Outrider about torque wrench's . It was quite enlightening.
I did think if the angle got too far off it would not
Function properly.
Torque = Force x Distance (perpendicular distance). This does not change the perpendicular distance. it being at an angle would though.
 

manyfunnies

New member
Find a part that you can easily slip a conventional socket on (like a normal head bolt)
Carefully use a magic marker to mark the bolt or use a punch and put a small mark on the bolt and the cylinder head.
Loosen the bolt about 1/2 turn and re-torque the bolt to 210 inch pounds.
Loosen the bolt again, Put your adaptor on the torque wrench and re-torque it to 210 inch pounds.
See see how much difference it makes in how the punch marks line up.
this exact test is why torque + angle is a thing.
 

flattop1

Dawg 89
Wondering now if retorqueing the bolt , would it land in the same spot?
The jest I got from The torque article is the torque wrench though sets things the same it really is. Nothing more then a certification the bolt was tightened.
After watching them rebuild them nhra fuelers
They weren't worried about anything but hearing that click. Bolts in hit with impact bam click bam click done.
 
Last edited:

manyfunnies

New member
Wondering now if retorqueing the bolt , would it land in the same spot?
The jest I got from The torque article is the torque wrench though sets things the same it really is. Nothing more then a certification the bolt was tightened.
After watching them rebuild them nhra fuelers
They weren't worried about anything but hearing that click. Bolts in hit with impact bam click bam click done.
The whole purpose of "torquing" a bolt is to stretch it. Typically you are stretching to 80% of yield. The only way to do this is to stretch it which is was rotating the bolt does. The problem with just straight up torquing is that friction is involved. Think of a nut in two situations: one with oil between in and the metal and another situation where the nut tries to gall to the metal (extreme case, would never happen BUT just trying to show a point). in the first situation you will be able to turn the nut a lot more because friction between the nut and the metal plate is less of a factor compared to the galling situation. you can see here that the second scenario will not have the same amount of stretch as the first. its not as good.

The solution is torque plus angle. You will see it written as 10 lb-ft + 180 degrees. What is happening is the engineers have said 10 lb-ft is enough torque to get everything squished together and 180 degrees is enough to go to 80% yield.

here is a good read:
https://www.norbar.com/en-us/News-Events/Blog/entryid/393/torque-and-angle-explained
 

flattop1

Dawg 89
Thanks.
As to the aforementioned article It alluded to the , torque plus angle situation . (Now I need to find that article.)
I do understand the bolt stretching and the affect different lubricants have on the readings involved.
Nice quick read . Interesting, they also stated the torque calculated was sufficient to bring things into an acceptable range .
Thanks
retrospect: the current method on a modern vehicle is torque/ angle thus stretching the bolt enough to deem it unreliable for use.
VS the old method of torqueing it to 85 ft lbs and reusing the bolt a undetermined number of times.
 
Last edited:

Outrider

Member
In my original post, referred to by Flattop1, I only discussed torque wrenches as that was what the question addressed. To expand on what mannyfunnies said above, while a torque wrench will deliver 32-33% fastener preload variation around the bolt circle on the best day of your life, with an experienced technician, for the reasons discussed in that post, angular turn is much more precise. Our standard (we developed a relatively simple computer program to calculate torque based on fastener and clamped materials, thread lube and resulting friction coefficient), we had no set value for initial baseline "snug". We found that initial snug was fine when established at 10% of what the calculated joint torque should be, then the required angular turn was applied (the program also calculated angular turn, which was convenient), in 3 increments, as with the torque wrench. Resulting fastener preload variation around the bolt circle was on the order of 15%, instead of 32% and up. If one has the means to calculate the required angular turn, or can get it from another source, angular turn is a more precise system for establishing fastener preload than use of a torque wrench.
 
Top