http://www.stormcam.org/wrench-set/
I just bought a new 1/2″ drive torque wrench, I’ve set it to 85 ft. lbs.?
my question is if I use the torque wrench with an extension do I lose any of the torque setting?
If you use an extension on the handle of the wrench (not recommended, by the way) you won’t lose any torque on your fastener. it will simply require less force to achieve the desired torque. (85 ft-lbs can be acheived by an 85-lb force applied a foot away, or a one-pound force applied 85 ft away
If, OTOH, you use an extension between the wrench head and the fastener and that extension is at something other than 90 degrees to the wrench handle you will either gain torque on the fastener (if it is farther from the handle than the centerpoint of the wrench head) or lose torque on the fastener (if it is closer to the handle than the centerpoint of the wrench head). The documentation you got with your wrench should give you a simple formula for adjusting your wrench settings to get the desired torque on your fastener.
Amon Tobin & Steinski – Ten Piece Metric Wrench Set