Re: Need opinions-Bearing Buddy trailer cap keeps falling off

[amuller]

What Bearing Buddy itself has to say: https://www.bearingbuddy.com/faqs

The most common reason is the hub bore diameter is wrong, because the hub manufacturer did not maintain quality control during production. Other possible reasons are listed below. The spindle may be too long, which could cause the nut or cotter pin on the end of the spindle to push against the Bearing Buddy® piston (when grease level is low), eventually forcing it out of the hub. Excessive removal and reinstallation of a Bearing Buddy® can wear down the Bearing Buddy® shoulder (the part that fits into the hub), which decreases the interference fit between the Bearing Buddy® shoulder and the hub bore. An out-of-balance tire and/or incorrect bearing torque can cause excessive "wheel play" or wobbling, which can cause a Bearing Buddy® to work its way out of the hub. Installing the wrong size Bearing Buddy® for the hub bore diameter. Theft.