Summary

Question about torque wrenches, is it bad to torque the bolt two times with the same torque value just to check that it was right the first time? OK it's a deceptively simple tool a torque wrench but there are actually a few aspects with how we use the torque wrench which are important to mention. Now I did cover this briefly as we were going through the demonstration of using plastigauge.

00:00 - Question about torque wrenches, is it bad to torque the bolt two times with the same torque value just to check that it was right the first time? OK it's a deceptively simple tool a torque wrench but there are actually a few aspects with how we use the torque wrench which are important to mention.
00:16 Now I did cover this briefly as we were going through the demonstration of using plastigauge.
00:21 But the problem with the torque wrench is that when we first move the bolt, we have to overcome the friction between the underside of the bolt or the nut and the washer that it's sitting on.
00:32 So what we'll find is if we actually plotted the torque, we'd see that initially the torque jumps up quite high and then once it starts moving, it drops back down.
00:40 So what I'm getting at here is if you have torqued a bolt up to the correct torque, if you check it again, you're going to find that the torque wrench automatically clicks before it starts to move so you're not actually really going to get a good indication of what the torque value is.
00:55 However, a good sanity check once we've gone through and torqued all of our fasteners up is just to double check.
01:02 Now all we're really looking for here is to make sure that every single nut or bolt that we're torquing up does actually result in our torque wrench clicking or beeping, indicating it is torqued.
01:12 That's not to say that we're checking the actual torque setting, all we're looking for is making sure that we haven't missed one stage and we find a nut that instead of perhaps being torqued to 75 foot pound is only at its second stage of maybe 35 or 50 foot pound.
01:27 In that case, obviously that one would move.
01:29 But really important and for exactly the same reason, when we are torquing a fastener up, we don't want to continually stop and start with our torque wrench when we are starting to come up torwards that final stage of torque, it's really important to have a continuous slow and smooth movement on that torque wrench.
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