Leaf Spring and Suspension U-Bolts

Order U-bolt kits online.  Each U-bolt kit has two U-bolts with nuts and washers.  We also make custom U-bolts (small and large orders).

To order online kits, click the type of U-bolt that you need. Find the U-bolt kit based on dimensions.  Use our U-bolt Inquire Form to find out pricing of U-bolt sizes not listed in our standard kits.  We also provide discount on large order U-bolt orders (bulk pricing)  –> enter you information in the U-bolt form to get pricing.

suspension round u-bolts  truck square suspension u bolts  semi-round u-bolts   custom u bolts and forged top round U-bolts  custom u bolts and Forged Top Square U-bolts  Semi-Round Forged Top U-bolt

Complete Leaf Spring U bolt kits that include two U bolts with deep nuts and hard washers.  Click U-bolt type that you require to go to further detail.  If you don’t see a U bolt that meets your specifications in our catalog, please use our inquire form.   We can also make custom suspension U bolts based on the dimensions that you need.  These custom axle u-bolts can be shipped anywhere by UPS.

U-bolts 9/16″ diameter and less are made from 1541 Grade 5 Material.  Ubolts 5/8″ diameter and greater are made from Grade 8 material.  U-bolts have a sufficient amount of rolled threads on each leg.We can also make most suspension u-bolts to your specifications and ship them out the same day.  Please let us know the dimensions (as shown below), the type of bend, and the application.  We can give you a price including shipping. 

Custom or Quantity U-Bolt Price Request Form



A U-bolt serves in four critical related roles:

u bolts and u-bolts

• Primarily, the truck u-bolts provide the force required to clamp the leaf spring and  related components firmly together. In addition to the leaf spring, these  components include the top plate, axle seat, axle and bottom plate.

• The properly installed u-bolt eliminates any flexing of the leaf spring in the area between the u bolts. This is particularly critical since the hole for the centerbolt  in each leaf acts as a stress concentration which would lead to rapid leaf  breakage if spring flexing was not totally eliminated by the U bolt clamping force.

• By firmly clamping the spring to the axle seat the horizontal forces acting on the centerbolt are greatly reduced which in turn prevents shearing of the centerbolt.

• Proper clamping of the spring by the truck u-bolts provides the desired spring stiffness  and contributes to maintaining the vehicle ride height and handling characteristics as originally specified for the vehicle.


How to measure a Leaf Spring U-bolts

how to measure u boltsRegardless of the bend type, all Leaf Spring U-bolts are measured in the same manner as shown here. The U-bolt size is given as

Diameter (A) x Distance Between Legs (B)  x Leg  Length (C).

Additionally the bend type must also be specified; either round, semi-round or square.




Do not reuse auto or truck Leaf Spring U bolts

• Used U-bolts will have rusted and damaged threads from the previous installation.

• A previously torqued U-bolt will suffer from distorted threads from the engagement of the deep nut.  Deep nuts should be tightened once and re-torqued, never loosened and retightened.

• A used u bolt may have suffered from fatigue as well excessive stress since achieving accurate torque with commonly used impact wrenches is very difficult.


       Rod/U-bolt Diameter Determination

Socket to Rod Size Chart

Socket Size Rod Diameter
11/16″ 7/16″
3/4″ 1/2″
13/16″ or 7/8″ 9/16″
15/16″ 5/8″
1 1/16″ or 1 1/8″ 3/4″
1 15/16″ 7/8″

  Torque Requirements

U-bolt Torque Pattern

U bolts must be tightened and torqued using a cross pattern sequence

-Tighten #1 then #4 to partial torque then partial torque #2 and #3

-Using the same sequence, fully torque U-bolt Nuts

U bolts that have been torqued to a set preload are recommended to be re-torqued after a short time to take-up the stretch in the set of the material.