Parts + Service

TRP® U-Bolt Kits

For Commercial Truck, Bus, and Trailer Markets

Why Choose TRP® U-Bolts

At first glance, U-bolts might look similar. If the diameter, threads, and shape match, you might think that they are the same. That’s simply not true. Knowing a little about the technology and process used to manufacture U-bolts can help you understand the differences between TRP® top-quality U-bolts and other value brands.

What Do U-Bolts Do?

The primary purpose of a U-bolt is to provide the force necessary to clamp the suspension components together. These components include the top plate, axle, axle seat, leaf springs and bottom plate. In turn, this:

• Firmly clamps the leaf spring to the axle seat, preventing a shear of the centerbolt by reducing horizontal forces on it.

• Eliminates flexing of the leaf spring, which also reduces stress concentration near the hole for the centerbolt in each leaf.

• Provides the appropriate spring stiffness to maintain vehicle ride height specifications and improve handling characteristics.

TRP U-bolt kits are available in a wide variety of sizes to fit most truck, bus, and trailer applications. When replacing U-bolts, there are a number of specifications to consider, including diameter, grade, and configuration. TRP® U-bolt kits are available in the following:


• Metric: M10-M32

• Inch: 7/16” - 11/4”


• Metric: Consolid 8.8, Consolid 9.8, and Consolid 10.9

• Consolid 8


• Round, square, semi-round, flattened, or combinations


TRP® brand U-bolts employ several controls to ensure the best quality metals are used in the production of the hardware. They collaborate closely with the steel mills to ensure that the raw materials meet strict quality standards before being made into U-bolts. By closely controlling the raw materials, fewer flaws are found in the finished product.


Once the raw materials, or blanks, are delivered, TRP® U-bolts are manufactured under stringent quality controls designed to produce the best quality product. Because of the strict quality controls used during manufacturing, all TRP® U-bolts meet Society of Automotive Engineers (SAE) standards.

U-Bolt Grades

A U-bolt’s grade is a measure of how strong it is. The higher the grade, the stronger the U-bolt. Grades 5 and 8 are the most commonly used grades in U-bolts. Grade 8 U-bolts offer a 40% increase in yield strength when compared to Grade 5. Although Grade 5 might be applicable in some instances, if the grade of the original equipment U-bolt is not known, Grade 8 is always the safest choice. All TRP ® U-bolts are made of Grade 8 material.

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