Comprehensive Boat Trailer Maintenance and Corrosion Prevention (Jan 2026)

Park the trailer on a level, concrete surface. If working on a driveway, ensure the tow vehicle is attached with the handbrake firmly engaged to prevent the trailer from pivoting. Use heavy-duty wheel chocks on the wheels not being serviced. In the Australian summer, work in a shaded area or under a marquee, as metal surfaces can exceed 60°C in direct sunlight, causing grease to liquefy and skin burns on contact.

Before mechanical work begins, the trailer must be chemically decontaminated. Mix your salt neutraliser at a 1:500 ratio in a pressure sprayer. Thoroughly coat the entire frame, paying specific attention to the inside of the C-channel or box sections where salt crystals accumulate. Allow it to dwell for 10 minutes (do not let it dry) before a high-pressure rinse. This prevents salt crystals from falling into open bearings during the service.

Using a hydraulic trolley jack, lift the trailer frame behind the spring hangers. Never jack directly on the axle tube as this can induce a permanent bow, ruining tyre alignment. Lower the trailer onto 2-tonne rated jack stands. Shake the trailer firmly to ensure stability before removing the wheels. Safety is paramount; never rely solely on a hydraulic jack.

Organise a clean 'surgical' area using a plastic tray or lint-free rags. Marine bearings are highly sensitive to grit. Even a single grain of Australian red dust introduced during the greasing process can act as an abrasive, leading to premature bearing failure within 500km. Ensure all new seals and bearings are out of their packaging and ready for immediate installation.

Remove the dust cap or Bearing Buddy using a soft-faced mallet. Remove the split pin and unscrew the castle nut. Carefully pull the hub assembly toward you, catching the outer bearing as it slides off. Place all components in a parts washer or a container filled with degreaser. Use a brass brush to scrub the spindle, looking for any signs of 'blueing' (heat damage) or scoring. If the spindle surface is not perfectly smooth where the seal rides, the hub will leak water immediately.

Clean the internal hub cavity of all old grease. Inspect the bearing races (the outer rings pressed into the hub). They should have a mirror-like finish. Any signs of pitting, 'frosting', or rhythmic indentations (brinelling) indicate the races must be replaced. To replace, use a drift punch to evenly tap the old races out from the opposite side, then press new ones in using a dedicated race driver or the old race as a spacer.

Place a glob of marine grease in the palm of your hand. Take the bearing and 'slap' the wide end into the grease repeatedly until the grease is forced up through the rollers and exits the top. This is known as 'packing the cage'. Simply coating the outside is insufficient and will cause failure. Repeat until the entire circumference is fully saturated with grease.

Insert the freshly packed inner bearing into the rear of the hub. Position a new marine-grade double-lip seal over the opening. Lay a flat block of wood over the seal and tap it into place until flush with the hub casting. Ensure the spring side of the seal faces inward toward the grease. Apply a light film of grease to the rubber lip to prevent 'dry start' friction damage.

Slide the hub onto the spindle, followed by the outer bearing, washer, and castle nut. Tighten the castle nut with a wrench while spinning the hub until you feel significant drag. This seats the bearings. Back the nut off roughly 1/6th of a turn (one flat) until the hub spins freely but has no detectable 'clunk' or play when rocked. Align the hole and insert a new stainless steel split pin—never reuse old pins.

Leaf springs are the 'rust engine' of a trailer. Use a wire brush to remove loose scale from the spring leaves. Apply a generous coating of Lanolin spray. Lanolin is derived from sheep's wool and is naturally hydrophobic, making it the superior choice for Australian boat trailers as it doesn't wash off as easily as petroleum-based oils and is non-toxic to marine life.

For trailers with mechanical disc brakes, check the caliper slide pins for movement. Salt often seizes these pins, leading to uneven pad wear. Apply a high-temperature silicone grease to the pins. For hydraulic systems, check the master cylinder fluid level and look for leaks at the bleed nipples. Australian heat can cause brake fluid to degrade; if it looks like dark tea, it requires a full flush with DOT 3 or 4 fluid.

Inspect the 7-pin plug. Use an electrical contact cleaner to remove the green copper-oxide build-up. Apply a small amount of dielectric grease (or even petroleum jelly) to the pins to seal out moisture. Check that the submersible LED lights are still sealed; if any moisture is visible inside the 'sealed' unit, the heat of the summer sun will eventually cause the internal circuitry to corrode and fail.

Adjust tyre pressures to the manufacturer's 'Cold Load' specification (usually 45-60 PSI for light truck trailer tyres). Inspect the sidewalls for 'spider webbing' or dry rot caused by high UV exposure. In Australia, trailer tyres often 'age out' before they 'wear out'. Any tyre older than 6 years (check the DOT date code) should be replaced regardless of tread depth.

Inspect the frame for 'white rust' or red oxidation. Lightly sand any affected areas or scratches from stone chips. Apply two coats of 93% zinc-rich cold galvanising spray. This provides sacrificial protection, preventing the surrounding steel from corroding. Ensure the ambient temperature is below 35°C during application to allow the solvent to flash off correctly.