Axle Hub Assembly

Two kinds of hub

The hubs in this category split by era. Modern Jeeps from the 1990 Cherokee XJ onward use a unit bearing hub: a sealed assembly with the bearing, hub flange and wheel studs built into one piece that bolts to the knuckle with three bolts. When the bearing wears, the whole unit is replaced, and on vehicles with ABS the wheel speed sensor is either built into the hub or bolts to it. Older Jeeps and Willys use a separate hub that rides on tapered roller bearings and races pressed into it, retained by a spindle nut; the hub itself is reused for decades and only the bearings and seals get replaced, unless the stud holes or the bearing bores are damaged. Rear hubs for the AMC Model 20 and the Dana 53 follow the same older pattern, with studs pressed in and a tapered fit on the axle shaft.

Symptoms of a failing hub bearing

A humming or growling noise that rises with speed and changes when you steer left or right is the classic sign of a worn unit bearing. Jacking the wheel and rocking it at twelve and six o'clock reveals play. On ABS equipped Jeeps a failing hub often throws an ABS or traction control light first, because the sensor gap changes as the bearing loosens. Pulsing in the brake pedal and a rotor that will not stay true can also trace back to a hub with runout. Do not wait: a unit bearing that fails completely can let the wheel wobble enough to damage the knuckle, the axle shaft and the brake.

Choosing the correct hub

• Position: front or rear, and left or right where the listing names a side, as with the Compass and Patriot hub and knuckle assembly.
• Axle model: a Dana 30 hub for a WJ differs from the Dana 44 hub on a JK; the bolt circle and bearing size change.
• Model year splits: Jeep changed hubs within a generation. The 2007 to 2012 JK front hub and the later JK hub are different parts, and the WJ switched during 2005.
• Sensor: confirm whether your Jeep has ABS and whether the hub includes the speed sensor. Hubs listed with the sensor fit ABS vehicles only.
• Stud thread: older hubs for Willys and early CJ use left-hand thread studs on the driver side. Match them.
• For the Trail Gear one-ton hub, match spline count, 30 or 35, and the housing it is intended for.

Replacing a unit bearing

With the vehicle on stands and the wheel off, remove the brake caliper, bracket and rotor, then the axle nut if the shaft passes through the hub. Unbolt the three hub bolts from behind the knuckle; they are usually tight and sometimes corroded, and a long 12 point socket helps. The hub may need persuasion from a slide hammer or careful taps to break free of the knuckle bore. Clean the bore and the axle splines, apply a light coat of anti-seize to the bore, slide the new hub on, and torque the three bolts and the axle nut to the factory figures. The axle nut torque on these Jeeps is high and specific, often well over 150 foot-pounds, and it sets bearing preload on some designs, so do not guess. Reconnect the speed sensor and clear any codes.

Older hubs with serviceable bearings

On a Willys or early CJ, the hub is repacked rather than replaced. Set the spindle nut to the factory procedure, usually a tightening torque followed by backing off to a specified end play, and install a new cotter pin or lock. A new hub is only required if the bearing races spin in the bore, the stud holes are stretched, or the drum register is damaged. Rear hubs on a Model 20 are a taper fit and pull with a proper hub puller, never a hammer.