A torque multiplier used with a 1/2″ torque wrench is the ideal way to check torque on the wheel nuts.
The X12 as an example is a 12 to one ratio so if you use a torque wrench on the input side to tighten the nuts and you are looking for 450 to 500 foot pounds, set the torque wrench for 40 ft/lbs and you end up with 480 foot pounds at the nut. But there are some losses through the torque multiplier so it is likely the actual torque on the nuts is something less than the theoretical 480. When I bought my X12 (it was $300 back then) the salesman told me to add about 5 foot pounds to the torque wrench to compensate for the losses through the gear reduction. or to keep it simple he said use 1/10th of the torque required.
I have no way to check actual torque with the X12 other than what the input force is, so I have always divided by 12 and added 5 foot pounds. No wheels have fallen off, and no cracks in my wheels so it has been close. I now use my 1″ impact set at the lowest possible setting and when I have checked using the X12 the nuts are sufficiently tight meaning they are all tighter than my target setting, but I have no way to determine how much tighter. An impact wrench has zero repeatability because different input air pressure varies the torque so I usuallly bottom out the nut and give it a short burst to tighten it a little further.
Over the years only once have I ever seen anyone check torque on a wheel lug nut and that was more than 20 years ago when Prevost was in the old Wilson Avenue shop. Two guys used a 4 foot torque wrench to tighten the nuts properly.
Jon and Di 2006 Liberty Elegant Lady, 2021
Jeep Grand Cherokee, 1950 Ford
Knoxville, TN
Owner of three Liberty Coaches since 1990
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