Originally Posted by leathermang

This may not apply to click type...
but my old torsion bar type reads in both directions...
I always use it when taking head bolts loose to see if they are all reading about the same amount..... that is not a direct indication of the pull down each is providing... sometimes it does indicate that a head gasket was allowing fluid to get to the threads and cause corrosion.... I think that if you don't pull on it more than the calibration is meant for it will make any difference.... anyway, how would one torque left handed threads if you can't use it the other direction?
It is just a calibrated spring.... and anyway torques are always given for bolts in ' ranges'... due to the usual inaccuracy of the tools AND the user technique..
Actually torque wrenche's main value comes not in how accurate the readings are but in being able to put more even pulldown onto the bolts and thus the gaskets being held....