How to Replace Boat Trailer Spindles

Repeated immersion contributes to wheel component failure, which can damage the spindle.

Boat trailer spindles support the weight of the boat and trailer load while transferring the load to the wheel hub and tires. Machined surfaces on the spindle create a sealing surface for the grease seal in the wheel hub and act as bearing journals for the inner races of the wheel bearings. Poor maintenance, harsh conditions, salt water immersion and age can cause the grease seal to fail and allow the grease to escape the wheel hub, causing corrosion, bearing failure and damage to the machined surfaces on the spindle. Replace damaged spindles to maintain the proper function of the wheel hub assembly. After the hub assembly has been removed, inspect the spindle for damage and make repairs.

Things You'll Need

• Needle-nose pliers
• Penetrating oil
• Large breaker bar
• Socket set
• Bearing puller
• Shop rag
• Cleaning solvent
• Anti-seize compound
• 2 new spindles
• 2 new cotter pins

Instructions

1. Inspect the spindle assembly to determine whether you have a bolt-in or welded spindle. Bolt-in spindles have a large nut visible on the inside of the axle-to-spindle connection. Welded spindles will not have a nut. Proceed with the removal process for bolt-in spindles.

2. Determine the axle type by inspecting the trailer axle. Leaf spring axles will have leaf springs separating the axle from the trailer frame. Torsion axles will have the axle hard-mounted to the trailer frame with a swing-arm-type assembly supporting the spindle.

3. Remove the cotter pin from the spindle-retaining nut with needle-nose pliers. Apply penetrating oil to the spindle nut and allow it to soak into the spindle nut assembly. Unscrew the spindle nut with a large breaker-bar and socket.

4. Push the spindle out of the axle connection with a bearing puller. Apply additional penetrating oil to the connection if the spindle resists separation. Clean the spindle socket on the axle with a shop rag and solvent to remove the penetrating oil and old anti-seize compound.

5. Apply a thin layer of fresh anti-seize compound to the spindle socket and insert the tapered end of the new spindle into the socket. Install the new spindle-retaining nut and tighten it according to the spindle manufacturer’s instructions. Install a new spindle retaining-nut cotter pin, using the needle-nose pliers.

Tips & Warnings

• Spindles may become difficult to remove after years of service and frequent water immersion, especially in salt water. Use a rubber or leather hammer to tap sideways on the threaded end of the spindle while pushing with the gear puller to overcome a stubborn connection. Heat the connection with a propane torch if you have a leaf spring-type axle and all else has failed to separate the spindle from the axle. Do not apply heat to torsion-type axles, as damage may occur to the rubber components in the axle.

• In a marine application, using bearing grease specifically formulated for use in salt water will resist the effects of repeated salt-water immersion and protect the bearings, hub and spindle from damage and corrosion.

• Welded spindles must have the welds ground off to remove the old spindle from the axle and the new spindle welded in. Due to the heavy loads supported by the spindle and the need to align the new spindle with precision, have the spindle replacement performed by a trailer service center, or replace the entire axle and spindle assembly.

References

• Capt. TJ Hinton; Commercial Fisherman; Gulfport, Mississippi

Resources

• Trailer Boats: Surviving a Trailer Breakdown
• Outdoor Alabama: Boat Trailers Are Not to be Ignored
• California Department of Boating and Waterways: Safe Towing Tips for Trailer Sailors
• California Department of Motor Vehicles: Towing Your Trailer Safely