Every time you replace a trailer bearing, you replace its race too. The race (also called the cup) is the hardened ring pressed into the hub that the rollers run on, and a new bearing in an old race wears out fast. Swapping races sounds intimidating, but with a drift, a hammer and some patience it is a driveway job.
The short answer
- Removal: drive the old race out from the opposite side of the hub with a drift, tapping in alternate spots around the race so it walks out straight.
- Installation: drive the new race in with a race driver (or the old race as a pusher), keeping it square, until it sits hard against the shoulder in the hub.
- Check: the race is home when the sound of the hammer changes to a solid ring and there is no gap at the shoulder.
Which races are in your hub
| Axle | Inner race | Outer race | Kit |
|---|---|---|---|
| 3,500 lb (10-inch drums) | L68111 | L44610 | 10-inch Timken kit |
| 5,200 to 7,000 lb (12-inch drums) | 25520 | 14276 | 12-inch Timken kit |
The race number is stamped on its edge. Both kits include both races, so you have everything for one hub. Check the Timken cross-reference if your numbers differ.
What you need
- A brass or soft-steel drift (punch), or a long flat punch
- A hammer
- A bearing race driver set (optional, but it makes installation easier), or the old race
- Solvent and rags
- Safety glasses. Hardened races can chip.
Removing the old races
- Strip the hub. Remove the outer bearing, pry out the seal and lift out the inner bearing. Clean out the old grease so you can see the races.
- Find the notches. Look into the hub from the opposite side. Most trailer hubs have two cutouts in the shoulder behind each race, which give the drift a place to land on the race's back edge.
- Drive it out evenly. Set the drift on the back edge of the race through one notch and tap. Move to the opposite notch and tap. Keep alternating so the race walks out straight instead of cocking in the bore.
- Repeat for the other race from the other side of the hub.
- Clean and inspect the bore. It should be smooth, with no scoring or signs that the old race was turning in it.
Installing the new races
- Check the number. Make sure the race matches the bearing (L44610 with L44649, L68111 with L68149, 14276 with 14125A, 25520 with 25580), and that the taper faces outward, toward where the bearing will sit.
- Start it square. Set the race in the bore and tap it gently around its edge until it starts evenly.
- Drive it home. Use a race driver disc of the right size, or set the old race on top of the new one as a pusher. Do not hit the new race's running surface directly; a dent there will ruin the bearing.
- Listen and look. When the race reaches the shoulder, the sound of the hammer changes from a dull thud to a sharp ring. Check that there is no gap between the race and the shoulder all the way around.
- Repeat for the other race, then wipe both clean.
Tip: if you use the old race as a pusher, it can get stuck in the bore once it is flush. Some mechanics grind a little off its outside diameter first so it drops back out easily.
When the hub is finished
If the old race has spun in the hub (the bore is polished, scored or oversize), a new race will not stay put. The hub needs to be replaced. The Black Series brake drum hub comes greased with both bearings installed, and it is the faster repair when a hub is beyond service.
Finish the job
With the races in, pack the new bearings, fit the inner bearing and a new seal, refit the hub and set the preload. Our Timken repack guide covers packing, and the bearing adjustment and torque guide covers the nut. Everything ships from Upland, California.