Torque Specifications for Suspension System U-Bolts and Shackle Bolts

Question:

Im doing routine maintenance on my 2007 Keystone Copper Canyon Sprinter 329FW. Are you able to tell me the torque specs for the u-bolts and also the spring hanger bolts? I just want to make sure everything is torqued properly before our next trip. Thx!

asked by: Tony R

Expert Reply:

The torque requirements for leaf spring u-bolts depend on the diameter of the u-bolts that are being used. The torque ratings are as follows:

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

The shackle bolts used between the springs and hangers do not require a specific torque rating because tightening the shackle bolts too much will squeeze the shackle straps against the leaf springs, and the whole suspension system will bind and cause problems. The best thing to do when tightening down shackle bolts is to use lock nuts, tighten them until they are snug, then back them off 1/4 turn. Lock nuts should be used because they resist loosening with vibration or torque.

I have attached two FAQ articles on trailer suspension for you to check out.

expert reply by: Amber S