Question about torque wrench use.

[Asterix]

Eh, the wrench doesn't matter all that much.

Buy what you prefer that will last a while and not break.

Read the NASA Fastener Design Manual (page 18). Even the best torque wrench only gives you +/-25 percent accuracy in preload, which is what matters. IIRC, Carroll Smith also discusses this in his Screw to Win book, but the NASA guide is free.

The problem is converting torque to preload (strain induced by stretching the bolt) involves friction between threads, and the nut and washer. That friction is highly variable and hard to determine. Breath on the surfaces and it changes.

For our purposes, I'm with IJ. Be consistent.

Asterix

 

[suprabad]

Any extension you use absorbs energy as it is stressed...Would I go as far as using an extension to torque something like a head? Probably not.

I don't know what you're using for sockets, but it's virtually impossible to torque the Supra head without using an extension. I use a short (3")extension. I doubt that a 1/2" drive, 3" long extension is going to flex...at least not at 70 or 80lbs.

Also, click type torque wrench is the only practical/reliable tool for the average guy, I can't imagine using anything else. I have experienced inaccuracies with them, but that was pilot error in that I hadn't had it recalibrated in 7 years. I pretty much have to own that one (adjusts dunce cap).

 

[87witmoreboost]

I don't know what you're using for sockets, but it's virtually impossible to torque the Supra head without using an extension. I use a short (3")extension. I doubt that a 1/2" drive, 3" long extension is going to flex...at least not at 70 or 80lbs.

No, a 3" extension will be absolutely fine. I should have been much more specific. We all know those head bolts require an extension like that. Get into extensions over 8" and the issues arise.

 

[suprabad]

Get into extensions over 8" and the issues arise.

Definitely.

It seems to me I've had to use long extensions w/ a torque wrench one or twice because of accessability issues, I just can't recall when. It didn't give me a good feeling.

I'm shocked to hear that the "needle" type of t-wrench is the most accurate. It's hard to believe 'cause they look so "mickey mouse".

 

[jdub]

Get into extensions over 8" and the issues arise.

Definitely.

It seems to me I've had to use long extensions w/ a torque wrench one or twice because of accessability issues, I just can't recall when. It didn't give me a good feeling.

I'm shocked to hear that the "needle" type of t-wrench is the most accurate. It's hard to believe 'cause they look so "mickey mouse".

Ummm...no. An extension does not effect the torque reading. Think about Newtonian physics...specifically the part about "equal/opposite" reaction.

Read this...start at post #11:
http://www.supramania.com/forums/showthread.php?t=65048&page=2

 

[Keros]

As I've understood it, a beam wrench will virtually never wear out... a "click" type will get worn out by use and can be thrown out of calibration by abuse; lay it gently into the toolbox, don't throw it . I use the beam wrench for wheel lugs and general duties, and the click type for awkward areas or places where consistency is key. Either way, user error is a factor.

 

[dumbo]

Ummm...no. An extension does not effect the torque reading. Think about Newtonian physics...specifically the part about "equal/opposite" reaction.

Read this...start at post #11:
http://www.supramania.com/forums/showthread.php?t=65048&page=2

thank you, they taught me that in school as well.
you can use a forty foot extension and still have the same twisting force at the end

and i'd never be caught dead using a needle type wrench..click, or digital but then again i can get freshly calibrated wrench everyday at work if i want.

 

[NavySupra]

the hand book for my 3/8" Snap-On click type says that the torque loss with straight extension or wobbly up to 15degrees is not worth calculating. I totally agree with being consistant, but there are times when that is not always possible. When torquing my exhaust manifolds on the 7.3L powerstroke I had to use a deep socket and a shallow socket on a 6" wobbly.

My 1/2" torque wrench is a real click type. Basic idea of the beam and needle but with an adjustable spring loaded indicator that "clicks" when tripped by the "needle" Old wrench, from my grandpa's tools but bang on

 

[87witmoreboost]

Ummm...no. An extension does not effect the torque reading. Think about Newtonian physics...specifically the part about "equal/opposite" reaction.

Read this...start at post #11:
http://www.supramania.com/forums/showthread.php?t=65048&page=2

Jdub:

I felt like shooting myself right after I read this. I took two FULL years of physics and mechanics and was too damn ignorant to think of things at a simple level. I push 145lbs on the ground, it pushes 145lbs back.



::hang:::bigun2::withstupi::slap::kickinthenuts:

 

[jdub]

I felt like shooting myself right after I read this.

LOL...don't do that
It's pretty easy to over complicate a problem...do it myself. Just ask my wife :biglaugh:

 

[87witmoreboost]

LOL...don't do that
It's pretty easy to over complicate a problem...do it myself. Just ask my wife :biglaugh:

Exactly, a popsicle stick and rubber band works great.

:yelrotflm