torque limiting extentions, how do they work?

[Seanz0rz]

so i was browsing harborfreight the other day and came across these:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92890

and i cannot figure out how they work! i was considering just buying them to figure it out, but i typically use a torque wrench on anything that needs even a semi precise torque.

i was just wondering if anyone knows how these work? i cant see any they slip, click, twist, etc. anyone have any experienc with them? i dont think i will buy them, just curious how they work.

[corax]

they will only work with an impact gun, which applies torque - releases - applies torque - etc. If you've ever used an impact gun with extensions, you'll know how you lose torque as you add longer extensions (ex. 3' of extensions to get to those upper bell housing bolts). "Torque Sticks" work on the same principle, except instead of length they use thickness - thinner extension widths transfer less torque than thicker extensions - kind of like a torsion bar. If you use them with a ratchet, you will overcome the twist in the stick and just keep adding torque to the fastener. An impact cycles though and when the fastener reaches torque all the impact does is twist the stick. Does that make sense?

They work decent but should probably only be used on lug nuts with an impact gun since they are not very precise (though they will get all the fasteners to the approx same torque, which is important in preventing uneven internal stress in "sandwiched" type rotors which can lead to warpage). When I was turning wrenches I would use the thinnest one (lowest torque) to get all the lugs snug in the air then run around with my torque wrench with the vehicle on the ground.

[Seanz0rz]

ohhhhhhh ok, i get it now. awesome.

its never something i would use, i do like to be precise with things that require a precise torque. just curious how they work.

[corax]

yeah, they're more of a time saver for flat rate techs who work on several cars a day - and I've only ever seen them used on lug nuts.

[4x4mike]

Lug nuts it is. I torque my wheels but hand so I know I can get the lugnuts off with the factory tire changing tools.