Wheel bearing hot spots/blue discoloration

KnowNuthin wrote:
Last time I packed the bearings I snugged the castle nut until the brake drum began to get harder to spin, then I backed off the nut a quarter turn and installed the cotter pin. Is this the correct method of preloading the bearings on a FW?...



...I've replaced many roller bearings on older American made cars... never had an issue... so I'm not really sure what the heck I'm doing wrong on our FW... any ideas?

The section in bold in your comments is the issue.

You overtightened the bearings.

Unlike auto wheel bearings, trailer axles do not require "preloading", trailer bearings are supposed to run a bit "sloppy".

In fact, if you observe the castleations on a trailer nut vs a auto you will notice the trailer nut has less castleations..

The correct procedure is outlined in the Dexter axle service manual..

HERE

See pages 52-53.

From those pages..

"Bearing Adjustment and Hub Replacement
If the hub has been removed or bearing adjustment is required,
the following adjustment procedure must be followed:

1. After placing the hub, bearings, washers, and spindle nut back on the axle spindle in reverse order as detailed in the previous section on hub removal, rotate the hub assembly
slowly while tightening the spindle nut to approximately 50 Ft. Lbs. (12" wrench or pliers with full hand force.)

2. Then loosen the spindle nut to remove the torque. Do not rotate the hub.

3. Finger tighten the spindle nut until just snug.

4. Back the spindle nut out slightly until the first castellation
lines up with the cotter key hole and insert the cotter pin.

5. Bend over the cotter pin legs to secure the nut.

6. Nut should be free to move with only restraint being the
cotter pin."

Notice the section in bold type..

Basically a 12" long wrench hand tightened unitl the nut stops moving, then with drum not rotating back off the nut slightly to release the torque.

The finger tighten nut.

If you can't get the cotter pin hole to align with a opening in the nut, back off the nut to the nearest opening from hand tight position.

Under no circumstance should you tighten the nut to get the cotter pin through.

This often results in the bearings fitting a bit sloppy or loose but on a trailer this is OK as you do not need to be precise like a auto.