Bolts Failing on Equalizer Hitch
I have an Equalizer Hitch with 1400 lb bars. Today I replaced the third pair of bolts and nuts that attach the head to the shank They are grade 8, 3/4" in diameter and 5" long. The threads failed on t...
Forum Discussion
Thank you all for your replies.
After reviewing the instructions (which I should have done earlier and not rely on my memory) it is clear that I confused the torque for the ball with the torque for the bolts. The correct torque for my fine threat bolts is 320 ft-lbs.
I have not personally tightened the bolts in several years. I certainly could have torqued to 420 ft-lbs at that time. I'll never know. The last two times it was done by a dealer and they may have over torqued them.
So my problem is almost certainly over torqued bolts.
Applying a known force at known distance is certainly a valid way of torquing. The error involved is in the value of the force, the measurement of the distance and the application point of the force. There is also an unknown error in the rented/borrowed torque wrench. In this application a certain small amount of error is not a problem.
Again, thanks for your help.
After reviewing the instructions (which I should have done earlier and not rely on my memory) it is clear that I confused the torque for the ball with the torque for the bolts. The correct torque for my fine threat bolts is 320 ft-lbs.
I have not personally tightened the bolts in several years. I certainly could have torqued to 420 ft-lbs at that time. I'll never know. The last two times it was done by a dealer and they may have over torqued them.
So my problem is almost certainly over torqued bolts.
Applying a known force at known distance is certainly a valid way of torquing. The error involved is in the value of the force, the measurement of the distance and the application point of the force. There is also an unknown error in the rented/borrowed torque wrench. In this application a certain small amount of error is not a problem.
Again, thanks for your help.
