I read this over at RL and thought it might be a good topic to save here. Thanks to the guys at RL (and here) for their help.
To determine the length of the breaker bar on a nut (such as the rear axle) and applying your weight (standing on the bar and not holding onto anything) to get a certain Torque, without the use of a Torque wrench, the following formulas can be used.
T= Torque (ft/lb)
W= Weight (lb)
L = Length (ft)
Example 1: You know T required (330 ft/lb) and your W (200 lb). Where on the breaker bar (BB) do you apply your weight?
L = T / W or 330 ft/lb / 200 lb = 1.65 ft
or 19.8 inches from the center of the socket.
Example 2: You know T required (330 ft/lb) and max length of the BB (1.65 ft). How much weight do you need to get the correct T?
W = T / L or 330 ft/lb / 1.65 ft = 200 lb
Example 3: You know max length of the BB (1.65 ft) and your W (200 lb). What is the Torque you can apply?
T = L x W or 1.65 ft x 200 lb = 330 ft/lb
max length of the BB can also be any point (from the center of the socket) or length on an infinite size bar.
I hope I wrote this out correctly. Let me know if I didn't. :cool:
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