Trailer Suspension U-Bolt and Shackle Bolt Torque Values

Updated 11/13/2020 | Published 11/12/2020

Question:

Hi, I was wondering if you guys have a torque spec chart for torqueing u bolts for axles. Also for torqueing shackle bolts. I just want to make sure im doing it correctly. Thanks

asked by: Scott H

Expert Reply:

The axle U-bolt torque spec will depend on the bolt diameter-

• 5/16 inch- 65 ft/lbs
• 1/2 inch- 45-70 ft/lbs
• 9/16 inch- 65-90 ft/lbs
• 5/8 inch-100-120 ft/lbs
• 3/4 inch-160 ft/lbs

Shackle bolts don't typically have a specific torque value. They're usually tightened until the knurled portion of the bolt pulls completely into the shackle strap and the bolt head is ran all the way down to the shackle strap and you have at least 2 threads extending past the face of the nut. I've linked to help articles that contain more details about how trailer suspensions work.

expert reply by: Mike L