I've been reading posts on steering components for the past couple of days, but I still feel compelled to ask for some advice.
Recently my 260z (late) has had steering problems. I've had the car for over a year, and while it's never steered perfectly, it's been a lot worse lately.
I get a fair amount of wander when travelling in a straight line at freeway speeds, and also some vibration at speed. Nothing beyond my control, but still intensely frustrating. Also, I was getting far more bump-steer than normal, as the car wanted to take off in either direction after hitting a bump.
I replaced the lower ball joints last weekend and did an inspection of the other steering components. Tie rod ends look a bit long in the tooth, but do not exhibit any signs of functional wear. Nothing else looked worn to me, so I greased everything up and threw it back together, did a cursory alignment, and went on my merry way.
The steering was very stable for about a day, and then the problems slowly began to emerge again, bad as ever.
I was concerned that I had forgotten to tighten something, so I jacked the car up again and spent some time fiddling with the steering.
Everything seemed nice and tight, and there is no play in any of the ball joints. There is no delay between turning the steering wheel and the movement of the tie rods. Baffling.
HOWEVER, I *did* notice that there was an inconsistency in the middle of the rack travel, when the wheels are facing forward. That is to say, when I am under the car, turning the wheels by hand, I can feel a slight "clunk" coming from the rack when I reach the middle of the travel. Then it smooths out again.
I put my hand on all the steering components when I did this, and the thunk is definitely the most powerful closest to the steering gear housing. This leads me to believe that my rack is worn in that one spot, the center position.
I never had any problems while I was turning, I suppose, so that makes sense.
I tried throwing more grease at it, but no dice. I tightened up the steering gear tensioner (the massive, massive screw), and it made things more stable but did not eliminate that "bad spot."
I'm scheduled to have a real alignment on Tuesday, but I don't want to bring it in just to have them say I need a new rack.
Is it possible that it's ANYTHING but the rack? The only ball joint I've not physically seen is the inner tie rod end on the driver's side. However, the vibration I'm talking about is equally strong on when I put my hand on either side of the steering gear housing.