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Here are the torque specifications for our NF fine thread U-bolts. The recommended foot-pound values for tightening the U-bolt nuts vary depending on the U-bolt diameter. It's important to adhere to these specifications for proper installation.
TORQUE-TENSION REFERENCE GUIDEA. Nominal Size or Basic Screw Dia. Threads per inch Tensile Stress Area (sq. in.) Clamp Load (lbs) Coarse Thread Series. 0.0026 275 0.0037 388 0.00492 511 0.006 633 0.008 835 0.0091 954 0.014 1471 0.0175 1841 0.0318 3341 0.0524 5505 0.0775 8136 0.1063 11162 0.1419 14899 0.226 22883 0.3345 33864 0.4617 46751 0.6057 ...
The U-bolt grade is a measure of the material's strength. Grade 5 and 8 are the most commonly used with grade 8 material offering an increase in yield strength of over 40% better than that of grade 5 material. This allows for higher torque levels, and thereby, improved spring clamping.
Compared to other fasteners, recommended torque levels for U-bolts are significantly lower. This is due mainly to the stress concentration effect of the U-bolt bend itself, the dynamic loading that the spring transmits to the U-bolt and the difficulty of acheiving even stress on both legs of a U-bolt.
u-bolt facts u-bolts on many suspensions are what provide the necessary clamping force to attach the springs to the spring seats. the clamping force allows' the spring to be attached permanently to the axle seat, prevents spring breakage at the centerbolt hole of the leaf, and to prevent the center bolt from being sheared off.
U-Bolts that have been well lubricated with an anti-seize compound will have a torque range between plated and unplated values. All the above values are general guidelines. The OEM Service Manual on specific models always takes precedence over values shown.
Drive the vehicle for a minimum of 10 to 15 minutes to seat components. After driving the vehicle, re-torque U-bolt locknuts to specified torque. U-bolt locknuts MUST be re-torqued at 4,500 kilometres following service, repair or. rebuild of the suspension.
