How to Change the Leaf Springs on a Dual-Axle Boat Trailer

Medium-size to large boats must be towed with a dual-axle trailer. The suspension system on a boat trailer is fairly simple, but like a truck or car's suspension system, boat trailers are equipped with leaf springs. These are elliptical-shaped pieces of steel that support weight and keep the axles aligned. If the trailer begins to start to sag or bottom out, which can be dangerous, it's time to change the leaf springs.

Things You'll Need

  • Lug wrench
  • Jack
  • Jack stands
  • Impact wrench
  • Replacement leaf springs
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Instructions

    • 1

      Park the boat in a boat slip while the repairs are made. Do not attempt this repair with the boat on the trailer.

    • 2

      Loosen the lugs on the rear tires with the lug wrench but do not remove them. Jack up the rear end and place the jack stands under the rear frame.

    • 3

      Finish removing the lug nuts and set the rear tires aside.

    • 4

      Loosen the bolts attached to the bottom of the U-bolts on the driver's side axle with an impact wrench. Lower the axle.

    • 5

      Remove the spring bolts from the shackle forks on each end of the leaf spring and remove the old leaf spring. Use the impact wrench to remove the spring bolts.

    • 6

      Hold the new leaf spring in place while inserting the spring bolts by hand to get them started. Tighten them with the impact wrench.

    • 7

      Repeat Steps 4 to 6 to change the leaf spring on the rear passenger side and then replace the rear tires and tighten the lug nuts with the lug wrench.

    • 8

      Jack up the rear end and of the trailer, remove the jack stands and then lower the trailer completely.

    • 9

      Repeat Steps 2 through 6 to change the leaf springs on the front driver and passenger sides.