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Old 06-19-2012, 11:09 PM   #1
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Big Bolt Torquing

Is everyone purchasing a torque wrench capable of 320 ft lbs of torque for the shank bolts? I couldn't find one locally. Even though the dealer installed mine, I'd like to have one to check the torque periodically.
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Old 06-23-2012, 07:52 AM   #2
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Quote:
Originally Posted by sellis1053 View Post
Is everyone purchasing a torque wrench capable of 320 ft lbs of torque for the shank bolts? I couldn't find one locally. Even though the dealer installed mine, I'd like to have one to check the torque periodically.
You don't need a torque wrench that is capable of that kinda weight unless you do that type of thing for a living.

Torque is measured in lb./ft. 320 lbs. of weight 1 ft. from the axis of the bolt is 320 ft/lbs. That is the same as 160 lbs. at 2 ft., and 80 lbs. at 4 ft.

If you have a socket to fit the bolt, and a large breaker bar to fit the socket, and a "cheater" pipe to fit over the breaker bar, then you can accurately torque those bolts.

1st, turn the shank in the receiver so that you have to push down to tighten to bolts.

I have torqued my bolts 2 ways. At first, I was using my weight divided by 12 (inches) to see what I would be exerting per inch if all of my weight was placed on a bar 1 ft from the bolt axis. Let's say I weigh 200 lbs. 200 divided by 12 = 16.7 lbs. per inch. Next, I need to figure how far out on the "cheater" pipe that is placed over the breaker bar. If I need 320 ft/lbs. of torque, then I need to center my weight 19.2" from the bolt axis (320 ft/lbs divided by 16.7 lbs. per inch that 200 lbs. will exert). I would mark the cheater pipe at that measurement, then place my hand centered of the mark, put my knee on my hand, and put all of my weight on the pipe at that point.

You don't really have to do the division by 12. 320 lb.ft. divided by 200 is 1.6'......bout the same as 19.2", but maybe not as quite as accurate when converting to inches.

Just plug your own weight into the formulas, and you will be good to go.

After reading about another member here using a scale to stand on, I am now using that method. I got a 4' piece of "cheater" pipe, put a union on 1 end, and cut the pipe so the ridge in the union was exactly 4' from the axis of breaker bar. I screwed the cut portion into the other end of the union for comfort. I can now stand on a scale with my hand on the union, push down on the union, and take the required weight off of the bathroom scales that I am standing on. For example, 320 ft/lbs., 4' out (80 lbs), me at 200 lbs, I push down on the bar until I see 124 lbs. (the bar weights 4 lbs. at the union).

With this method, you need to have the scales directly under the pipe union, and the pipe as level as possible.

This is probably a lot more accurate that many RV places that just use an impact wrench to torque the bolts.
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