If you've recently purchased a tandem axle trailer kit, you may need to install the axles and springs to the frame. A tandem axle trailer is built to haul heavy loads. The axles are suspended by high-fatigue steel leaf springs that absorb the force of repeated impact from changes in the road surface. The two leaf springs on each side of the trailer are connected across an equaliser bar. The equaliser bar transfers the impact between springs to disperse the weight. A properly installed suspension system on your tandem trailer will protect the axles and your cargo from damage.
Raise the trailer frame by placing blocks at the four corners.
Locate the middle hangers on either side of the trailer. Bolt the centre hole of each stabiliser bar to a middle hanger using a socket wrench.
Fasten shackle straps to either side of the equaliser bars using a bolt and socket wrench.
Bolt one end of each leaf spring to a shackle strap using a socket wrench. The four leaf springs should hang to the ground.
Place the front axle across the right and left front leaf springs. Raising one leaf spring at a time, fasten the free end of each leaf spring to the front shackle hanger on either side of the trailer using a socket wrench. Make sure the axles are seated at the centre of each leaf spring. The axles should be suspended from the leaf springs.
Secure each front axle to its leaf spring using a U-bolt, retainer bracket and socket wrench.
Place the rear axle across the rear leaf springs. Raising one spring at a time, fasten the free end of each leaf spring to a rear shackle hanger using a socket wrench. Make sure the axles are seated at the centres of the leaf springs. The axles should be suspended from the leaf springs.
Secure the axle to the leaf springs using a U-bolt, retainer bracket and socket wrench.
Tighten all the bolts to manufacturer torque specifications using a torque wrench. Remove the blocks and lower the trailer.
Perform this activity with the help of another person.
Use care when near or under a raised trailer frame.