Duck-boat, jon-boat and utility-trailer owners ask for bearings the same way: "five-lug hub, what Timken kit do I need?" The lug count is a clue, not an answer, because the bearing is decided by the spindle, and two trailers with five-lug hubs can have different spindles. This guide gives you the common combinations, then the two checks that make the answer certain.
The three common axle classes
| Axle rating | Spindle | Inner bearing | Outer bearing | Usual hub | Usual lugs | Kit |
|---|---|---|---|---|---|---|
| 2,000 lb | 1-1/16 in both ends, straight | L44649 / L44610 | L44649 / L44610 | Idler hub, no brakes | 4 or 5 | Not currently kitted; see below |
| 3,500 lb | 1-3/8 in inner, 1-1/16 in outer | L68149 / L68111 | L44649 / L44610 | 10-inch drum or idler | 5 on 4-1/2 in | 10-inch Timken kit |
| 5,200 to 7,000 lb | 1-3/4 in inner, 1-1/4 in outer | 25580 / 25520 | 14125A / 14276 | 12-inch drum | 6 on 5-1/2 in, or 8 on 6-1/2 in | 12-inch Timken kit |
The "usual lugs" column is where the confusion lives. Most 3,500 lb axles are five-lug, but so are many 2,000 lb boat-trailer axles, and the two take different inner bearings. Six-lug hubs are almost always the 5,200 to 6,000 lb class and eight-lug the 7,000 lb, and those share a bearing set.
The two checks that settle it
1. Read the number off the old bearing. Every Timken cone has its number stamped on the face. L44649, L68149, 14125A and 25580 are the four you will see, and the inner and outer may differ. This is the certain answer and it takes a minute with the hub off.
2. If the hub is on, measure the spindle or the drum. A tape across the brake drum reads close to ten or close to twelve inches, nothing in between, and that separates the 3,500 lb kit from the 5,200 to 7,000 lb kit. For an idler hub with no drum, the inner spindle diameter separates the 2,000 lb axle (a straight 1-1/16 inch spindle) from the 3,500 lb axle (a 1-3/8 inch shoulder stepping down to 1-1/16 at the outer end).
The axle's own plate, if it is still legible, gives the rating directly and points at the row.
What is in a kit, and how many you need
Each kit covers one hub: matched inner and outer cones, their races, the grease seal and grease. A single-axle boat trailer needs two, a tandem four. Do both hubs on an axle at the same time; a new bearing beside a worn one is a repeat job in a season.
The complete greased hub is the alternative when a race has spun in the hub or the drum is scored past its limit. It comes with both bearings fitted and greased, and it is the spare worth carrying on a trailer that hauls to remote water. A fresh cotter pin for every hub, every time.
Boat trailers: the two things that differ
They get dunked. A hub that is submerged warm draws water in past the seal as it cools, and that is why boat-trailer bearings fail on trailers with a tenth of a camper's miles. Let the hubs cool before launching where you can, and inspect yearly regardless of miles; our horse-trailer bearing guide covers the same calendar-not-odometer rule for a trailer that sits.
Bearing protectors. Spring-loaded grease caps keep positive pressure on the grease so water cannot enter. They work, with two cautions the boards raise repeatedly: they loosen if the cap was fitted to a hub bore that is worn or out of round, and over-greasing through them forces grease past the inner seal onto the brake shoes. A cap that keeps coming loose is telling you the hub bore is worn, not that you need a bigger hammer.
Preload, which decides how long the job lasts
The question "how tight should trailer bearings be" is the most-asked on every trailer board and the answer is the same everywhere: tighten the castle nut while turning the wheel to seat the bearings, back it off to loose, then snug it to finger-tight and fit the cotter pin at the nearest slot. The wheel should spin freely with no knock at the rim. Our Timken repack guide covers the procedure and the grease.
The 2,000 lb kit we do not stock
The straight 1-1/16 inch spindle with L44649 at both ends is the most common small boat-trailer axle, and we do not currently offer a kit for it; the 10-inch kit's outer bearing is the same L44649 but its inner is the larger L68149. If your old bearings read L44649 at both ends, tell us, and we will say so plainly rather than sell you the wrong kit. It is on our list.
Send a photo of the stamped number or the axle plate and the drum measurement, and we will confirm the kit before you order. Everything ships from Upland, California.