1. Remove and inspect all wheels, hubs, and brake drums.
2. Inspect suspension for wear.
3. Check the tightness of the hanger bolt, shackle bolt, and U-bolt nuts per recommended torque values.
4. Check brake linings, brake drums, and armature faces for excessive wear or scoring.
5. Check the brake magnetic coil with an ohmmeter. The magnetic coil should check 3.2 ohms (+/- 0.3 ohms). If shorted or out of tolerance, replace.
6. Lubricate all brake moving parts using a high-temperature brake lubricant.
7. Remove any rust from the braking and armature surfaces of the drums.
8. Inspect oil or grease seals for wear or nicks. Replace if necessary.
9. Inspect and grease wheel bearings.
In addition to these recommendations, check all trailer tires (including spares) for signs of dry rot, correct air pressure, faulty air valves, uneven tire wear, and overall tire wear and damage. Get a high-quality air pressure gauge, and learn how to use it so that you can inspect tire pressure before each trip. (Trailer tires should be replaced if they’re worn or damaged. Otherwise, replacement every three to five years is a rule of thumb.)
It is also important to service the wheel bearings every 12,000 miles, or annually, regardless of mileage, due to moisture build-up. Keep a spare set of wheel bearings in your trailer in case of premature failure. Be sure to inspect trailer wiring and lighting; inspect door latches and grease the doors; inspect the floor (remove any rubber mats so the entire floor can be examined); and inspect and lubricate mechanical moving parts, such as the hitch and suspension parts. If the trailer has been sitting for a while, check for wasp nests, spider webs, and other creatures.