Description The 8K U-Bolt Kit secures your trailer’s axle to the leaf springs. It keeps suspension parts tight under load and stops the axle from shifting. This kit fits most 8,000 lb trailer axles with 3-1/2″ round tubes, the standard size for heavy utility and equipment trailers. Each kit includes four U-bolts, two mounting plates, and eight heavy hex nuts. The U-bolts use 9/16″-18 threads and measure about 8″ long from the bottom of the bend to the end of the threads. The spacing of the legs matches the 3-1/2″ axle tube diameter so the bolts wrap snugly around the axle. This U-bolt mounting kit works with leaf spring suspension systems on single and tandem axles. It clamps the axle to the 1-3/4″ or 2″ wide leaf springs and spring seats (sold separately). That makes it a true hardware match when you rebuild or service suspension setups on utility trailers, car haulers, livestock trailers, and flatbeds. Install the U-bolt kit after you set the spring and axle alignment. Slide the U-bolts over the axle tube. Place the mounting plates under the spring stack. Thread the nuts on and tighten evenly. Torque the 9/16″ nuts to spec to prevent loosening under load. Trailer builders and service techs trust these kits because they include all the parts needed to mount the axle securely. They deliver consistent performance and reduce suspension noise and movement.