TruckSpring Times

Truck & Trailer Parts - News & Information

Replacing Your U-Bolts

When installing your U-bolts, it is important to remember to keep your truck on a level surface that is as close to flat as possible. Jack up one side, put the truck on the jack stands and locate the damaged U-bolt that you would like to replace. Take off the nuts of the u-bolt and remove. Old, rusted u-bolts many need to be cut off. Place the new U-bolt around the leaf spring. Connect the two portions of the "U" with two nuts. Use a torque wrench for the installation. Tighten them in a cross pattern, gradually bumping up the torque.


Consult with the vehicle or suspension manufacturer for your particular truck model's advised torque level. The pressure of the U-bolt should be distributed in an even manner along the top plate's width. Make sure the proper fit is attained for a solid clamping force. Lower your truck back to the ground. Don't forget that the U-bolt should be kept tight throughout the year. Mark your calendar to re-torque the U-bolt after 500 miles worth of driving after the replacement. Your spring will settle much more nicely as a result. 

Proper Fit of your U-bolts

If your U-bolts are semi-round, proper fit is essential to maintain clamping forces. Unlike square or round bend U-bolts that do not vary much from one manufacture to another, semi-round bend shapes are usually unique to a particular vehicle or suspension manufacturer. A mismatch between the shape of the semi-round U-bolt and its mating parts can cause an inability to provide the proper clamping force.



In figure 1 the U-bolt has been formed with a shape that causes all the pressure to be concentrated at the center of the suspensions top plate. As the leaf spring flexes under normal operation, the U-bolt will work into the top plate which will lead to loose U-bolts and possibly premature leaf spring failure.


In figure 2 the shape mismatch is causing the pressure to be concentrated at the corners of the top plate. This will cause deformation of the top plate and as a result the clamping force will be diminished and premature leaf spring failure may be the result.


In figure 3 the proper U-bolt fit has been accomplished. The shape of the U-bolt matches the suspensions top plate resulting in even pressure distributed along the width of the top plate allowing for proper clamping forces.

U-bolts are a vital part of your suspension system and should never be reused. Failure to replace or properly fit your U-bolts when maintaining or servicing your suspension could cause premature failure of your leaf springs or other components with catastrophic results.

We have been custom bending and installing u-bolts in our service department for years. If you have any question about install you u-bolts or need new ones, call 1-800-358-4751 to talk to one of our leaf spring suspension experts.

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