A direct-replacement idler hub from Lippert for 3,500-lb trailer axles. Correct bolt pattern, correct stud size, correct bearing fitment -- no guesswork, no adapter rings.
The Lippert 122098 is a genuine OEM-style replacement idler hub engineered specifically for 3,500-lb trailer idler axles. Whether you're rebuilding after a bearing failure, replacing a cracked or worn hub, or prepping a spare before hitting the road, this hub gives you factory-correct fit without machining or modification.
It carries the 5 on 4.5" bolt pattern (five 1/2" wheel studs on a 4.5" bolt circle diameter) that is standard across a wide range of single-axle and tandem-axle travel trailers, cargo trailers, and fifth-wheel RVs in the 3,500-lb axle class. Wheel compatibility spans 13" through 15" trailer wheel diameters -- the most common sizes for this axle rating.
Matched to 3,500-lb idler axles -- the most common single-axle rating in the RV and trailer market.
Five 1/2" studs on a 4.5" BCD -- compatible with a broad range of 13", 14", and 15" trailer wheels.
OEM Lippert quality. Part number 122098, also cross-referenced as Lippert vendor part 62-0855.
Designed for idler axle positions -- no brake flange. Not for use on brake axles without a separate brake drum assembly.
An idler hub is the rotating wheel-mounting assembly on a trailer axle that does not have a brake actuator. It houses the inner and outer wheel bearings, retains the bearing grease via a grease seal on the inboard side, and provides the wheel stud pattern for mounting the wheel. Idler hubs are used on the non-brake end of a brake axle or on a fully idler (no-brake) axle in a tandem setup.
Common reasons to replace an idler hub include:
Using the OEM Lippert hub means the bearing cups (races) are already pressed in to the correct depth and bore diameter. Aftermarket hubs sometimes have tolerance issues that cause premature bearing failure. With part number 122098 you get a hub built to the same specs as the original axle assembly.
The Lippert 122098 hub for 3,500-lb idler axles is designed to accept the standard bearing set used across this axle class. The typical bearing combination for a 3,500-lb trailer hub in this configuration is:
Bearings, seals, and the dust cap are not included with the hub. Always install new bearings and a new grease seal whenever the hub is replaced. Reusing old bearings in a new hub defeats the purpose of the rebuild.
Some 3,500-lb Lippert axles use an EZ-Lube spindle with a grease fitting at the center of the spindle nose. If your axle has this feature, confirm the dust cap style when ordering -- the hub casting is the same, but you will need a vented EZ-Lube dust cap rather than a solid press-in cap. The 122098 hub accommodates both cap types.
Replacing an idler hub is a straightforward task for anyone comfortable with basic trailer maintenance. General steps:
Incorrect bearing adjustment is a leading cause of hub and bearing failure on trailers. Too tight causes heat buildup and premature bearing destruction. Too loose causes wobble and eventual stud or spindle damage. Follow the tighten-then-back-off method above, or use a dial indicator to set 0.001" to 0.003" of end play. Verify adjustment after the first 10 miles of travel.
To get maximum service life from your new Lippert 122098 hub: