L&H Threaded Rods Corp.
Original Equipment Manufacturer

For our OEM customers, L&H stocks large quantities of raw material from which we manufacture products to meet exact specifications. Our feedstock is purchased to proprietary chemistries and physical specifications in heat lot quantities from hot rolled bar and rod mills. We saw cut or shear our U-Bolt blanks to length and then chamfer, thread and bend to your specifications. We produce SAE grades 5 and 8 equivalent or we can modify the steel to meet your specific requirements. Transportation for inbound and outbound shipments is provided by our subsidiary, Scarlet & Gray Corp. This ensures a dedicated means of transportation and provides our customers with reliable service. For all of your U-Bolt requirements, we encourage you to contact: L&H Threaded Rods Corp.

Spring Shops

For our spring shop distributors, L&H provides end threaded rods with the unique and innovative "CENTERMARK" - a positive location and identification system. We also manufacture the Centermark bender, which bends U-Bolts in a converging path and thus protects the critical shoulder area. L&H maintains a finished inventory of end threaded rods in diameter sizes from 3/8" to 1-1/4" in SAE grades 5 and 8 equivalent. Additionally, we carry hardware items such as high nuts, washers and other related suspension parts to complete our product offerings. For all of your U-Bolt requirements, we encourage you to contact: L&H Threaded Rods Corp.
A U-Bolt serves in four critical and related roles:

1. Primarily, the U-Bolt provides 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.

2. 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.
3. 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.

4. Proper clamping of the spring by the U-Bolts provides the desired spring stiffness and contributes to maintaining the vehicle ride height and handling characteristics as originally specified for the vehicle.

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Micro-Alloyed, Modified Steel

L&H Threaded Rods Corp. produces U-Bolts to SAE-J429. This material is a cold drawn, stress relieved, micro-alloyed, 1541 modified steel.

The physical requirements:
• 150,000 PSI Minimum Tensile Strength.
• 130,000 PSI Minimum Yield Strength.
• 120,000 PSI Proof Load.
• 35% Reduction of Area.
• 10% Elongation.

* If hardness and tensile strength do not agree, tensile strength shall govern. This cold formed type of U-Bolt is now widely accepted by many OEM's as a replacement for heat treated U-Bolts.

Aftermarket or replacement U-Bolts are oftentimes formed at the spring shops or repair facility. A heat treated U-Bolt, due to its microstructure, will not form easily. Therefore, aftermarket U-Bolts are produced from a cold drawn product. This allows for ease of forming with the high strength equivalent to a quenched and tempered product.
Recommended U-Bolt Torque

For Cold-Formed U-Bolts
For Cold-Formed U-Bolts which 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.

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.

U-Bolts Must Be Tightened and Torqued Using A Cross Pattern Sequence

Snug U-Bolts in the seqence shown.
Tighten completely in the sequence shown.
Check U-Bolts for tightness after 100 miles

Why you should not reuse U-Bolts

Suspension U-Bolts are manufactured with a smooth rolled thread, while the mating Hi-Nuts are manufactured with sharp cut threads.

When a U-Bolt is tightened to its recommended torque level, the U-Bolt threads stretch as they mate with the Hi-Nuts. Although not always visible to the naked eye, this damages the threads. Removing the Hi-Nuts from the U-Bolt will cause a cross - threading that will not allow the U-bolt to be adequately retorqued.

Common practice in most maintenance facilities is to use an impact wrench to tighten U-Bolts. Consistent, accurate torque is next to impossible to obtain with an impact wrench, and in most cases, an over-torqued fastener is the result.

L&H recommends using a torque wrench when installing U-Bolts.