The Stovebolt Site Forums The Shop Area The Tool Chest Torque Wrench Question

2 Questions regarding torque wrenches:

1.) What is the correction factor when using an extension? ?? +\- per inch of extension

2.) Is it correct to convert from inch pounds to foot pounds i.e. 12 inch pounds = 1 foot pound

Thanks!!

to answer question #1 you need to specify where your extension is. If it's between the socket and the torque wrench you need no conversion. If it's on the torque wrench handle being used for leverage then it's going to change your final torque amount. I don't have a chart or anything, I just use the proper wrench for the job to ensure accuracy. Question #2 is 12 in. lbs. = 1 ft.lbs.

No an extension does not make a difference (ie to rise the torque wrench above the rockers) as long as it a good quality extension and does not twist form the torque. You can get torque multipliers in a gear head format in a 4:1 ratio, so if you want 100ftlbs you set the torque wrench to 25lbs, you can also use what looks like an open end wrench , they come in various lenghts from 6", 12" 24", one end has a male 3/8 or 1/2 drive and the other end female to fit the torque wrench.

If your extension is much longer than 4``, the extension does "twist"which will affect your torque (lesser) (but not by much). The longer the extension, the more will be lost.

Luke's right on the extension effect. I use my left hand to hold the extension so it stays in line with the bolt. Also, u-joints will reduce your torque values.

If you're using a cheater on the wrench (not recommended) the conversion formula is:
Length of wrench with cheater divided by length of wrench without cheater times the torque reading.

To convert from inch-lbs to foot-lbs divide by 12, from ft-lb to in-lb multiply by 12.

also, torque values specified are for threads lubricated with engine oil. Dry threads have friction, but the amount varies with the finish and material. If anti-sieze is used, reduce the torque value by 10%.

Here's a good website on torquing.
http://www.arp-bolts.com/pages/tech/fastener.html

Thanks for all the replies! Once again, Stoveboltland comes through!