Man there are quite a few things you did that discredits the accuracy of the test. 1. You need to be aware of where you hold the torque wrench as you are applying torque. Too close or too far away from the handle area and you are applying more or less torque than indicated. 2. Once a bolt is torqued to a specific value, say 60 ft lbs, you can’t test it at 60 on the same bolt. It takes more torque to move that bolt..maybe 70..something about static friction. Torque values need to be reached as the bolt is moving. So you need to loosen, and then get to 60 again. 3. Torque wrenches are usually more accurate from 20% of full scale. So 5-80 ft lb is mostly accurate from 16ft lbs on.
Based on best practices, you have to move the bolt/nut in a smooth consistent movement and make sure you move up in torque at least with 5 ft lbs. So if the bolt/nut was torqued to 68 ft lbs and you want to go to 70 ft lbs, make sure you loosen the bolt/nut first to under 65 ft lbs. When you have multiple bolts uts, it is best to torque in stages to increase clamping load. So, for example, in case of tires lug nuts start to torque them (in cross pattern) to 50 ft lbs first then 65 ft lbs followed by 80 ft lbs.
@@rickyparrish2570 That’s not true at all. It does matter where you hold a torque wrench, hence why some wrenches are longer and others are shorter depending on the purpose and application it’s used for. (Torque = force * length) hence why it’s called a foot pound. If you have a 2 foot long handle, and at one end you have a socket connected to a bolt, and on the other end you have a handle to hold. If you hold the center of this bar (not the handle) you’d turn a 2 foot long handle into a 1 foot long handle. That means if you applied 10 pounds of force in the center of the bar to rotate the bolt clockwise, you’d be applying 10 FOOT pounds of torque. (12 inches = 1 foot) On the same bar, if you held it at the handle (where it’s supposed to be held), then you’d apply 2 times the amount of torque if you used the same force (10lbs), aka 20 foot pounds. It’s not rocket science, plus I don’t see any reason to not hold one by the handle anyway unless it’s in a hard to reach place, in that case you should probably find another way of tightening that fastener by using a different approach.
The digital indicator comes calibrated to within +/- 2% and I haven't used it much. It's not a perfect indicator but its more than accurate enough to improve the calibration of a clicker wrench.
I think the test should be made on a welded bolt. Just need to measure the settings of the click wrench against the reading of the AC Delco. Then you could reach some +/- 5% (summary of the errors of the two units, in theory, in the midscale range). Which is better than +/- 10% in the begining, I agree. When You get +9% error to the click wrench, that could be really sth between +7% to +11%, with regard of those +/-2% from the digital gage.
@@johnnywong83 great question. I am assuming the acdelco is accurate within the specified range. The calibration of the clicker torque wrench will not be as accurate as if were taken to a real place, but it should be sufficient for my application.
Thanks for sharing this Car Fanatic! I have worked with Calibration Houses before and the subject of Calibration and the procedures associated with it can vary quite a bit while still being under the ISO/IEC 17025 standard (or the famous Accredited Calibrations vs unaccredited which are both used on the industry). So I totally get that this is a quick sanity check to confirm a wrench, we are not calibrating this wrenches to a standard (where we consider Test accuracy ratios, Test Uncertainty ratios etc.) or to build a spacecraft! lol so thanks for your effort putting this video together bud!
I don’t have one of these so I don’t know if it has a zero button, but when did you zero the digital TW?. The wrench hanging on it in position is already registering torque. It may be why your numbers are off.
Your whole test is based on an assumption that the digital torque wrench adapter is accurate which many have proven to be off way past their allowance. The best way is a known weight at a known distance from the center of rotation and some math.
Not to takeaway anything from using torque wrenches, but why torque in the first place? The answer is to place a preload in the bolt (torque actually only exists when the wrench is attached and force applied). So threads are simply a spirally wound inclined plane. As you might imagine, friction matters pushing a load up a slope. And friction has two types, static and dynamic friction. Everyone has experienced (I expect) that it takes more to get the load moving than to keep it moving. Measuring what it takes to start moving (static) is not terribly comparable to dynamic (which is the correct usage). Having said all this studies indicate there is up to a 30% variation in preload for the same applied torque. Factors for this variation are clean threads, finishes of surfaces and oil/lubricant. Oil or use anti seize on the threads when not specified = potentially more preload and over stressing due to reduced friction. This is one reason you occasionally see single use torque to yield fasteners, the yield is the bolt stretching (preload), this then removes much of the variability due to friction which is hard to predict…. Where you can gain access you sometimes see measuring the stretch on the bolt specified. Then there is ‘smart bolt’ technology…. a whole another level…. Ultrasonically measuring stretch. I still use my torque wrench…. Just understand it isn’t an exact science and what you apply (or not) to the threads matters.
Why not just hang an actual weight measured exactly one foot from the center of the bolt with the wrench at as close to exact horizontal as possible. Maybe even use a calibrated spring or digital hanging scale and just pull on it, regardless of the angle or direction of the wrench. Take out all mechanical variables, or as close to all as is possible. You're just using a yard stick to measure another yard stick.
