1993 Pontiac Grand Prix Front end noise

I have a 1993 Grandprix with over 250,000 miles on it and is making noise in the front end when making a turn. There is a large click that will occur when making a turn when the car ii in motion. Don't know if it has something to do with weight shifting when moving. I've changed the tie rod, ball joints, struts, hub spindles, rotors and pads. The car is solid underneath. I've even had the mechanic take apart and recheck to ensure nothing was loose. He even checked the motor mounts and bushings. This does not happen when driving a straight line or changing lanes. There are no problems when hitting bumps or pot holes. A mechanic suggested having it taken to a collision shop and having them chain it down to see if there may be a hair line crack in the frame or sub frame that may be causing this during a stress load. What could possibly be making that click sound when turning. I noticed when I was parking in a parking lot and when I made a turn going up on a ramp it did not make that click sound. It only happens when level or front end is lower than the rest back of the car. That means the weight is shifting back away from the front. What does it mean. Please help.