Hi Gary,
Did your mechanic replace the king pin bushings and hone for proper fit? If the bushings are worn, when you tighten the lower king pin nut, it may cause the king pin to bind. With proper fit, when all it tightened, it should move back and forth with ease...
Sometimes you can get away without replacing the king pin bushings (use existing bushings) and gain add'l "play" with the various size shims that come with the king pin kits.
Then the next question is... did your mechanic squirt in some new grease in the top, middle and bottom fittings?
I am lucky that, here in Memphis, there is an alignment shop that has been there since way before Elvis
, and besides doing great alignments, they also are very knowledgable with the 'ol king pins.
Please let us know the outcome and be careful drving to the alignment shop...
Bob
bpossel (Memphis, TN.)
'71 280SL / '97 E320