I've searched, and thoroughly gone over everything I can think of. My steering wheel has slight vibration at freeway speeds -- POSSIBLY at lower speeds, but the car's not a Cadillac so it's road imperfections. Vibration becomes uncomfortable traveling at 70+

Front UCAs and LCAs have spherical bearings instead of rubber.
Upper Ball joints are spherical and in tact.
Lower ball joints were switched to roll center adjusters (J's racing).
Wheel bearings checked, in good condition
Tie rods checked, seemingly in good condition.
Wheels are balanced and true.
Everything is tight/torqued to spec.


What else am I missing? Could it be an issue with the steering rack itself?

 

Warped rotor, or something with brake pads? I have the same problem and it started after I had to slam on the brakes to avoid hitting the side of a truck. Just a guess.

 

^^^^^I think this guy hit it on the head.
If you have in fact made those adjustments to your suspension and still have the problem I'd put my bottom dollar on it being Warped Rotors which WILL ONLY instill vibrations at freeway speeds, Lower speeds as they get worse. If you start feeling them at 40mph...you're heading down a bad path.

 

it's not when i'm braking. i know what warped rotors feel like. it's slightly more noticeable when i'm on accelerating vs cruising. rotors are new, high end pieces, and always cooled down properly when i drive aggressively.

anybody have any pertinent advice?

 

ttt

 

i too have had a small vibration past 60mph. its not wheel balance. its not tires either. i checked my balljoints/tie rods and had my rack end bushing changed before. the only thing i can think of left thats rotating is the inner axle joint is ripped and probably bad. i shold replace it anyway, but im just too lazy. its not a crazy vibration, just pretty much always there.

 

this is gonna sound stupid but check your spindles cuz mine got bent and i had decent vibration in the front end at those speeds and even lower. more than likely it is either a bad wheel balance or you could have a bent rim. i work at town fair tire so i see this problem more than most people do. if it has anything to do wit the tires it could be either a belt shift or a flat spot or just become out of round cuz a tire is still made outta rubber even though it has the steel belts and all that good stuff. bent rim like i said before could be a possibility as well. check ball joints, tie rods, and wheel bearings. good luck