MR-STANG

I'm installing Corsa Axle Backs today, and have a question about using extensions with Torque Wrenches. If It is a straight extension, do I need to adjust the torque settings?
Example if the clamps call for 45 ft lbs, and I'm using an 12" extension, do I need to apply more torque? does this make sense to anyone?
THanks
LJS

karman

I know what you are thinking.
If you are using the extension to a socket type torque wrench and still have the center of the wrench over the center of the bolt, there is no difference.
You should have no problem as long as you stay lined up.
The problem comes if there is a change of angles or other attachments changing the relationship.
With an open end type wrench (which most people don't have), using a different size head (or length) necessitates re-calibration.

anthony05gt

It's not important to be too accurate like it is on a rod journal bolt or something like that.

MR-STANG

That's what I figured, thanks!

classix_stang289

the longer the extension the less torque you get i believe. and i believe its done in 12inch incriments.

so i believe for every 12inches you have to add 1 ft lb. your taking torque away by using the extension.

karman

http://home.jtan.com/~joe/KIAT/kiat_3.htm
"From time to time people have asked me if it is OK to use an extension with a torque wrench. The answer is yes. Using an extension or reducer with a torque wrench does not affect the accuracy. Others have asked if it is OK to use a universal joint with a torque wrench. The answer is NO. Universal joints change the torque as the drive angle increases. I checked this out with my torque tester. The results are shown in Figure 8c. Don’t use universal joints with torque wrenches."
Now here are the calculations for the other type of wrench he is not using:
http://www.norbar.com/Calculators/To...0/Default.aspx

classix_stang289

i stand corrected, very cool find. i saw this guy once using a universal joint on a torque wrench and he was pulling the wrench towards himself and manages to crack himself in the head and i heard he had gotten something like 27 stitches. he must of lost control of the angle he had.

TORQUE WRENCH + UNIVERSAL JOINT=

habu

+1 Tighten it down as tight as you can get it. If this was a suspension piece or vital engine part or something that the correct torque was critical I'd say yeah, but an exhaust clamp I wouldn't think of it. I've got mine locked down way past 45ft/lbs I'd guess.... used a 1/2 drive and got it until I couldn't go any more, no problems.

I do understand being accurate and all maybe it's they backyard mechanic in me

nonsensez9

it kind of depends on your torque wrench. Mine, for example, has exactly one setting....sort of.... turning the handle will make it longer or shorter and therefore change the amount of force that it takes to make it "break" or hear the click. On the other hand, if you have a torque wrench that has a gauge in the head, it probably doesn't matter if you have an extension

TacoBill

If you choose to use an extension (to lenghten the torque wrench), use the following formula to set your correct torque value.

(T x L) / (L + E) = Adjusted torque value (what you set on your torque wrench)
T= target torque value
L= length of torque wrench in inches (end of handle to center of socket)
E= length of extension in inches (center of socket to center of bolt)

Example:
If using a 1" Crow's Foot extension, here's the way the formula works out.
(76 x 12" torque wrench) / (12" torque wrench + 1" extension) = 70.15 lb-in torque. This is what you would set the torque wrench to.

Srt2stang725

when i torque my wheel nuts I have to use an extension because of the dish....I use a clicker type torque wrench set to 100 ft/lbs, The extension is probably about 6 inches and I also use a 1/2 inch drive to 3/8 drive reducer, then a deep socket. Am I totally screwing up the torque amount?

karman

No, if you maintain the center of your 1/2" inch drive with the center of the lug nut.
You may need to support the end of a long extension at the drive to maintain the relationship.
The longer the extension, the more it tends to go askew without support (6" may not be a problem).

Srt2stang725

yeah i hold the top (ratcheting mechanism) with one hand and torque with the other, so it stays on center

karman

It is best to loosely hold the extension not the wrench itself (possibly throwing the torque reading off).
Of course, lug nuts are not the most critical torque on a car.

nonsensez9

ignore that post... I thought you were extending the handle. d'oh!

Anthony k

the real question is why use a torque wrench to install a axleback?

classix_stang289

some people sleep better at night knowing everything is done proper. but i do agree with you, if i can get my clamps tighter on my exhaust without breaking anything im all for it dude.

RadBOSS

Not the torque, but you would be better in the long run with a 1/2" deep socket at that torque level. At 100 ft-lbs you are close to pushing your luck with a 3/8" drive. I just broke a 3/8" drive recently working on the front suspension.

Taco Bill has the compensation factor correct , but that pre suppose that the crows foot is maintained in exactly opposite direction (180 deg) to the torque wrench handle, if not, all bets are off and the moment relationship changes. At plus or minus 90 degress to the handle, there is no correction.

Length of the extension does not change the torque, but the wrench handle will move further due to the torsional deflection of the extension.

For small angles (5 - 10 degrees) the U-joint does not loose that much torque, and is a life saver when needed. For other than spin in or out, high angles should be avoided (who would try to torque one at 60 degrees?).

Srt2stang725

what do you mean by crows foot?

karman

http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_94+1484+770696?cm_ven=PPC&cm_cat=I-search%20(Google%20Adwords)&cm_pla=handtools&cm_it e=crows%20feet%20wrench
An open end wrench (one that attaches to a socket wrench).
Think about it.