Causes for Hub Castle Nut to Come Loose After Installing and Using Hubs

Question:

About a year ago I bought two sets of these bearing kits. After replacing he bearings and races I have been having issues with my hub its coming loose. I have had to re tighten them three times now. I have bent the tabs in the locking washers like I am supposed to. Am I missing something else that would cause the nuts to come loose? Thank you for your help.

asked by: Eric G

Helpful Expert Reply:

A tang washer like # 5-101 or # 5-71 has a tab to secure the castle nut on the spindle so that it cannot rotate or back off on the threads. If the tang washer tab (or a cotter pin) is still in place in the notch on the castle nut (as in the linked photo) the nut should not be able to move.

The only other place where slack in the hub's fit could develop is at the back side where the grease seal installs. This is the portion of the spindle noted by the arrow in the linked diagram. If the castle nut were tightened too much initially this could potentially deform the metal part of the seal and allow for some slack.

The only other possibility I can think of is that the hub's bearings and races were not properly seated all the way inside the hub. If this were to be the case the fit on the spindles might seem snug enough at first but after many rotations the seal could deform and cause the loose fit.

The proper tension on the castle nut can be found by tightening it by hand until it stops freely turning; then back off the nut by one notch and secure that position with the cotter pin or tang washer.

expert reply by: Adam R