3 years and 5K miles ago I did a complete rebuild of the front suspension including rubber bushings, new sealed lower ball joints, new upper ball joints (in original upper control arms), new wheel bearings, tie rod ends and shocks. 5K miles later and I was starting to feel some play in the steering. Turns out the tie rod ends were shot with visible sloppiness in the joint and there was play in the upper ball joint. I understand from some research that even with new upper ball joints the wear in the socket can create problems but only 5K miles on a tie rod end seems odd.
So I replaced the tie rods with SNG’s “new and improved” and re-shimmed the upper ball joint per the manual setup procedure and it all feels solid again with no obvious unnatural wheel movement. I’m using a DIY alignment kit from https://www.quicktrickalignment.com/ which covers camber/caster/toe. The caster angle measurement involves the +/-20 deg sweep of the wheels abd measure the delta in degrees (kit comes with a great wheel clamp and digital level gauge). I’m finding the caster angle is not very repeatable, Over the last week I have made the measurement over 20 times and can get readings on the same wheel from 0.5 to 3.3 degrees. The car is in the mid-laden position using the specified setting links. I have driven the car in and out of the garage multiple times to let the suspension settle but am still stuck with this non repeatability. Sometimes the caster reading will change without even rolling the car forward / back. To a lesser degree the Camber is also fluctuating by about 0.4 degrees.
I have tried wrenching on the wheel and the stub axle nut to induce movement but no obvious play is present. Any thoughts on what would cause this fluctuation? Worn upper ball joint socket?