Loading...
Starting at low prices, AutoBuffy stocks multiple leaf spring axle U-bolt kits from top OE-quality brands. U-bolts clamp the axle housing to the leaf spring pack, keeping the rear axle located and transferring braking and acceleration forces correctly. When U-bolts stretch, snap, or loosen, the axle can shift dangerously and suspension geometry is lost.
The most important variables are U-bolt diameter, thread pitch, and leg length — all must match your axle tube diameter and spring pack thickness exactly. Beyond fit, material grade and coating determine how long the kit survives road salt, heat cycles, and the clamping loads from heavy payloads or towing.
| Option | Best for | What you get |
|---|---|---|
| OEM-spec replacement kit | Daily drivers and vehicles that see light to moderate loads; restoring factory ride quality | Correct diameter, leg length, and thread pitch matched to original specs; includes nuts and washers; straightforward swap with no modifications |
| Grade 5 carbon steel kit | Light trucks and SUVs used for occasional towing or hauling on paved roads | Higher tensile strength than standard hardware; zinc or black oxide coating for basic corrosion resistance; good balance of cost and durability |
| Grade 8 / alloy steel heavy-duty kit | Trucks used for frequent towing, off-road, or high-payload commercial work | Significantly higher yield and tensile strength; resists stretching under repeated heavy loads; often paired with thicker washers and prevailing-torque nuts |
| Lifted or long-leg U-bolt kit | Vehicles with a suspension lift or add-a-leaf packs that have increased spring stack height | Extended leg length to accommodate the taller spring pack; available in Grade 5 or Grade 8; prevents the dangerous under-thread engagement that stock-length U-bolts cause on lifted setups |
Safely support the frame on jack stands and allow the rear axle to hang freely so the spring pack unloads before you remove the old U-bolts. Clean the axle pad and spring perch contact surfaces before seating the new kit, and hand-thread all nuts evenly before applying final torque in a cross pattern to keep the spring plate seated flat. Re-torque to spec after 50–100 miles of normal driving to account for initial settling.