Originally Posted by ~XxPornxX~
Theres torque level settings built into them, using them daily for a living they know how much is too little and to much by feel/sound. I worked at the benz dealer ship for a while just out of school. Just about every tech in there laughed at me when i first started and torqued each nut with a wrench.
Keep in mind these guys flag hours and the last thing on their minds is to take time on your nuts. The also make torque sticks (impact gun) for noobs that you often see use them at americas tires. With that said, if im at a shop and i see an unknown impact ft-lb ratings @ X psi i would never use it on my own wheels. Just lightly zip them down and torque by hand. I have my own gun and know its feel/sound.
Try to have an impact gun calibrated, you will get a good laugh out of the calibration house.
Torque settings? put more pressure in you get more torque, less pressure less torque. "feel/sound" is plain old laziness. I'm a mechanical engineer and have been wrenching on my own cars and with friends for almost 20 years. I have few impact guns and the settings and variables are very inconsistent every-time.
There is a reason why there are torque specs on bolts. DO NOT OVER-TIGHTEN THEM, bolt stretch and failure of threads when over-tightened. All wheel bolts are fine pitch threads they do not have the same strength as a coarse thread bolts.
Every-time I had a friend or family member call me for help changing a flat on the side of the road, the car was at a shop or dealership recently and they did a tire rotation. Guess what every-time the bolts were overtorqued by a wrench monkey/parts swapper with an impact gun. I bring my 24" breaker bar and a cheater pipe to get the wheel lugs off.
Wrench monkeys using impact guns to put on wheel lugs is plain old LAZINESS.