U Bolts

U bolts are the dimensionally specified fasteners used to clamp the rear leaf spring pack to the axle housing perch. Each U bolt wraps around the axle housing and passes through a spring seat plate, with nuts torqued at each threaded leg to generate the clamping force that holds the spring pack firmly on the axle perch. Correct U bolt specification, condition and clamping torque are essential to rear axle location, as a loose or undersized U bolt allows the spring pack to move on the perch under load, affecting rear axle alignment, handling and braking stability.

U bolts are a service replacement item that should be renewed rather than re-torqued when they have been removed, as the thread and leg dimensions can stretch under initial torque and the original clamping characteristics cannot be reliably restored. The range covers square top and round top configurations in a range of internal diameters and lengths to suit a wide variety of axle housing profiles and spring pack dimensions. Thread specifications cover both M12 and M14 to match the specific seat plate and nut hardware of applicable platforms. Two kits are required per vehicle. All products carry a three-year warranty.

Why Upgrade Suspension?

U bolts that have been removed during spring or axle servicing should always be replaced with new hardware rather than refitted. Once torqued to specification, U bolt legs experience plastic deformation at the thread and bend radius that makes it impossible to achieve the original clamping force reliably on re-installation. Reusing old U bolts risks under-clamping the spring pack on the axle perch, which allows movement under braking and acceleration loads and introduces rear axle instability that worsens progressively with continued use.

Replacing with correctly specified new U bolts ensures the spring pack is clamped to the axle perch at the correct force from the moment of installation, maintaining correct rear axle location and delivering consistent, stable handling under all load and road conditions.

U Bolt Range

The U bolt range includes:

• Square Top Universal U Bolts: M12 thread U bolts with a square top profile in a range of internal diameters for axle housing profiles that use a square bend at the crown of the U bolt.
• Round Top Universal U Bolts: M12 and M14 thread U bolts with a round top profile in a range of internal diameters and leg lengths for axle housing profiles that use a rounded crown configuration.
• All products are sold as a pair. Two kits are required per vehicle to clamp both sides of the rear spring pack.

Why Purchase U Bolts?

Including U bolt replacement as a standard part of any rear spring, axle or differential service ensures the spring pack is correctly clamped at every service rather than relying on the residual clamping characteristics of hardware that has already been torqued and removed. For workshops, stocking the correct U bolt sizes for commonly serviced platforms avoids delays and ensures every rear spring service is completed with correctly specified new hardware.

Selecting the correct U bolt requires matching the internal diameter to the axle housing profile, the leg length to the spring pack depth and seat plate configuration, and the thread specification to the seat plate hardware. The range covers the most common configurations in a single subcategory for straightforward selection.

Compatible Vehicles

U bolts suit a wide range of vehicles, including:

• Any rear leaf spring platform requiring U bolt replacement as part of a spring, axle or differential service, where the correct internal diameter, leg length and thread specification matches one of the available sizes in the range.
• 4WD, ute, commercial and passenger vehicles with rear leaf spring suspension where U bolts have been removed and must be replaced with new hardware before the spring pack is re-clamped to the axle perch.

Installation and Support

U bolts are designed for accurate installation at the rear leaf spring axle perch clamping position. Installation time is approximately one hour per kit. Two kits are required per vehicle. The correct U bolt must be selected by matching the internal diameter to the axle housing, the leg length to the spring pack and seat plate depth, and the thread specification to the seat plate nuts. For additional technical assistance, a dedicated support team is available to help confirm correct product selection for the specific platform and axle configuration.

Repair and Upgrade

U bolts are manufactured from quality steel engineered to deliver consistent clamping force at the rear spring axle perch under sustained load, vibration and environmental exposure. The range covers both square top and round top configurations in M12 and M14 thread specifications across a range of internal diameters and leg lengths to suit the most common rear axle and spring pack configurations. All products carry a three-year warranty.

Who U Bolts Are For

U bolts are a practical solution for:

• Professional workshops completing rear spring, axle and differential services on leaf spring platforms requiring correctly specified replacement U bolts to ensure the spring pack is re-clamped at the correct force after every removal.
• 4WD owners and experienced DIY users replacing rear leaf spring U bolts as part of a spring service, lift kit installation, axle removal or any other rear suspension work that requires the spring pack to be unclamped from the axle perch.
• Anyone requiring dimensionally specified replacement U bolts in the correct internal diameter, leg length and thread specification for their specific rear axle and spring pack configuration.

The right U bolt delivers correct spring pack clamping force at the axle perch, maintains correct rear axle location and ensures stable, predictable rear suspension performance under every load and driving condition.

Shop U Bolts

Explore the full U bolts range and find the right specification for your vehicle. With square top and round top configurations in M12 and M14 thread across a range of internal diameters and leg lengths, you can select the correct U bolt for your axle housing profile and spring pack configuration and complete every rear spring service with confidence.