Awesome project—fresh bearings make a trailer tow smoother, run cooler, and save you from roadside drama. Here’s a clean, no-nonsense walkthrough with the little pro details DIY guides often skip (preload, grease choice, races, torque, and safety).

Before you start

• Parts: New inner & outer bearings (match by part number stamped on old bearings or hub), matching races, new grease seals, new cotter pins, new dust caps (optional but wise).
• Grease: NLGI #2 high-temp wheel bearing grease (lithium complex). For boat trailers, use a marine NLGI #2 (water resistant).
• Tools: Floor/bottle jack, jack stands, wheel chocks, lug wrench/torque wrench, drift/punch + hammer, bearing/race driver (or socket that matches race OD), seal driver (or flat block), adjustable/box wrench for spindle nut, pliers, rags, solvent (mineral spirits/kerosene), nitrile gloves.
• Do not: Spin bearings with compressed air (can grenade), mix old races with new bearings, or reuse seals.

1) Remove wheel & hub

1. Chock the opposite wheel. Break lug nuts loose on the ground. Jack and support the trailer securely; remove wheel.
2. Pry off dust cap.
3. Straighten and pull cotter pin (or pull the nut retainer/castle cap).
4. Remove spindle nut & washer. Catch the outer bearing as you slide the hub toward you an inch.
5. Pull the hub/drum straight off the spindle. Lay it face-down (studs down).

If you have brakes:

• Drum brakes: You just removed the drum+hub together—fine.
• Disc brakes: You’re removing a hub/rotor. Support the caliper if you unbolt it—don’t hang by hose.

2) Remove old inner bearing & race(s)

6. Flip hub face-down; pry out the grease seal (destroy it—it’s single-use). Remove inner bearing.
7. Drive out races (both inner and outer) from the opposite side using a punch on the race lip; work around evenly. Clean all grease out first so you can see the race ledges.

Inspect:

• Spindle journals and shoulders: no scoring/blueing.
• Hub bore & race seats: no pitting/spin marks.
• Brake surfaces: OK and oil-free.
  If a race spun in the hub (loose fit), the hub is toast or needs a sleeve.

3) Clean & prep

8. Wipe spindle clean. Clean hub thoroughly with solvent; blow dry with low air or rag (don’t spin parts).
9. Lightly grease the spindle and the hub’s bearing cavity.

4) Install new races

10. Start each race square in its bore, small ID facing inward. Drive with a race driver (or large socket) until it seats firmly against the shoulder all around. You’ll hear the tone change when seated. Do not nick the race surface.

5) Pack bearings the right way

11. Hand-pack or use a packer: press grease from the large end until it oozes out the small end all around. Coat the rollers and cage. (Proper packing is critical to longevity.)

6) Assemble hub

12. Flip hub face-down. Drop inner bearing (small end inward) into its race.
13. Tap in a new grease seal flush and even (lip faces the bearing).
14. Flip hub face-up; smear a thin film of grease on the outer race. Set the outer bearing in place (you’ll seat it on the spindle).

7) Install hub & set bearing preload (endplay)

15. Slide hub straight onto the spindle carefully over threads; don’t nick the seal.
16. Install flat washer and spindle nut.

Preload/endplay procedure (common tapered bearings):

• While spinning the hub by hand, tighten the spindle nut to ~30–50 ft-lb (40–70 N·m) to seat the bearings and purge excess grease.
• Back the nut off ¼ turn.
• Now snug the nut finger-tight (just to zero play) and then back off only enough to align the cotter pin hole (typically 1–2 flats).
  Target endplay ≈ 0.001″–0.005″ (0.025–0.13 mm). You should feel just a hint of free movement when rocking the hub; it must spin freely with no drag.

17. Insert new cotter pin; bend legs. (If using a retainer, install it now.)
18. Tap on a new dust cap (a bit of grease inside the cap helps prevent condensation).

8) Refit wheel & torque

19. Mount wheel; snug lugs in a star pattern. Lower to ground. Torque to the wheel/axle spec (common trailer steel wheels: 90–120 ft-lb, but verify your spec). Reinstall any hub cap/trim.

9) Repeat & bed/adjust brakes (if applicable)

• Electric drum brakes: After reassembly, adjust star wheel until shoes lightly drag, then back off to a faint rub.
• Hydraulic/disc: Verify rotor is clean; pump brakes before moving.

First miles: critical rechecks

• Spin & feel after a short drive (5–10 miles). Hubs should be warm or slightly hot to the touch but not scorching. One hot hub = too tight bearings, bad seal, dragging brake, or under-greased pack.
• Re-torque wheel lugs after 25–50 miles.
• Recheck hub play: grasp at 12 & 6 o’clock; a faint click is OK, wobble is not.

Pro tips (worth their weight in grease)

• Match parts: Don’t mix new bearings with old races. Bearing & race are a mated set (e.g., L44649/L44610, L68149/L68111, etc.).
• Boat trailers: Use bearing buddies or Vortex/油 bath systems if equipped; still inspect annually.
• Carry spares: One spare inner/outer bearing set, races, seal, cotter pins, dust cap, small tub of grease, gloves. Trailer trips get a lot less stressful.
• Grease type: Stick to one chemistry (don’t mix soaps). If changing types, clean everything thoroughly.
• Storage: Jack stands under frame to take weight off tires/bearings for long storage; spin wheels occasionally.

Common mistakes to avoid

• Over-tightening the spindle nut (cooks bearings).
• Reusing seals or cotter pins.
• Driving races in crooked or on the wrong side (check orientation).
• Getting grease on brake friction surfaces. Clean rotors/drums with brake cleaner if contaminated.
• Ignoring a loose or noisy hub (“growl” or “roar” under load = failing bearing).

Quick checklist (one hub)

• Wheel off, dust cap off, cotter out, nut/washer off
• Hub off, bearings & seal out, races removed
• Spindle & hub cleaned; new races seated
• Bearings hand-packed; inner bearing + new seal installed
• Hub on spindle; outer bearing, washer, nut installed
• Preload set, cotter in, dust cap on
• Wheel on; lugs torqued
• Short test drive; heat & play check; re-torque after 25–50 mi

If you want, tell me your axle rating or the bearing numbers stamped on your old bearings and I’ll map the exact replacement part numbers and seal size for you, plus the correct lug torque and any brake adjustments specific to your setup.