Torque Ratings for Trailer U-Bolts on 3" Round Axle

Updated 02/10/2025 | Published 06/29/2020

Products Featured in This Question

3" Round Trailer U-Bolts (Qty 2)

(132)

$33.49

3" Round Trailer U-Bolts 9/16" Diameter (Qty 2)

(222)

$28.51

Question:

Torque specs for Ubolts on 2006 Montana 5th wheel model, 3650 Rk. Are torque specs the same for round ubolts as well as square ubolts? Thanks!

asked by: Stephen H

Helpful Expert Reply:

Trailer U-bolts will have different torque specs depending on their diameter. For your 2006 Montana 3650RK 5th wheel trailer, which will likely have 3" round axles (though you will want to verify), you will need either 3" Round Trailer U-Bolts 9/16" Diameter # SP01-080 or 1/2" Diameter # SP01-060.

The correct torque specs are:

- 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

I have added a link to a help article on trailer suspension which this info as well as a lot of similar information

expert reply by: Kyle S

Dave P.

2/10/2025

Kyle, why do the torque specs have a range, ie... 9/16 inch bolts 65ft-lbs - 95ft-lbs? That's a big difference. How do we narrow down exactly what ft-lbs to torque to?