What is the Torque Spec for Trailer Suspension U-Bolts

Updated 02/05/2018 | Published 02/04/2018

Question:

What is the proper torque for u-bolts for a 2-3/8inch 3500 lb axle? Also, what is the proper torque for the shackle bolts for the same setup. Thank you.

asked by: Stuart

Expert Reply:

The correct torque spec for trailer suspension u-bolts will depend on the the diameter of the bolt. You will want to use the following depending on bolt size:

1/2" bolts: 45 ft/lbs - 70 ft/lbs
9/16" bolts: 65 ft/lbs - 95 ft/lbs
5/8" bolts: 100 ft/lbs - 120 ft/lbs
3/4" bolts: 140 ft/lbs - 160 ft/lbs

The Replacement U-Bolt part # 176400-Z has a 1/2" diameter bolt therefore, I recommend applying around 70 ft/lbs of torque. As for the shackle straps, there isn't really a specific torque rating. They have to be snug but the spring still needs to be able to move.

expert reply by: Conner L