Torque for U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles

Updated 04/09/2025 | Published 06/28/2018

Question:

What is the correct amount of torque for these bolts?

asked by: Robert M

Expert Reply:

The U-bolts on the U-Bolt Kit for Mounting 8,000 lb Round Trailer Axles # APUBR-35 are 9/16". The torque specs for 9/16" bolts on trailer suspension 65 ft/lbs - 95 ft/lbs. Torque specs depend 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

expert reply by: Kyle S

Anthony S.

4/8/2025

I have a question for you , I have Lippert 8000 lb axels on my Fifth wheel , while inspecting them I found the u bolt nuts not to be very tight . I would like to torx them down to spec . The nuts are 7/8” could you tell me what that would be?

Jameson C.

4/8/2025

@AnthonyS What is the diameter of the U-bolt? 1/2 inch diameter bolts should be torqued between 45 ft/lbs and 70 ft/lbs. A 9/16 inch diameter bolt should be torqued between 65 ft/lbs and 95 ft/lbs and a 5/8 inch diameter bolt should be torqued between 100 ft/lbs and 120 ft/lbs.

Anthony S.

4/9/2025

@JamesonC Thank you