04_Sport_LS
Dedicated LVC Member
As Joe suggested... do the control arm first... then get it aligned. Vibration could be a ball joint. Especially if at 65-70 mph.
Advice taken. Re-checked the suspension and drivers side upper control ball joint is shot. Also went back and somewhat corrected the outer tie rod ends that were installed and measured there distance on each side. Car performs much better. But definitely doing upper control arm and alignment.Best to check out the ball joints first... and replace as necessary. Otherwise you will be paying for an alignment twice.
To explain:
The reason you jack up the control arm... is because the shock/spring is pushing down on the lower control arm... keeping tension on the ball joint.
By jacking up the control arm..
you take the tension away... so that the only weight that is on the ball joint is the wheel assembly, brakes, and upper control arm. Only about 100lbs... vs several hundred pounds of spring tension.
Doing it this way makes it easier to diagnose the ball joint... instead of disassembling everything to check it. And you NEVER want to try to remove the nut on the ball joint with it under spring tension. Things can get real ugly really fast... and deadly.
The shock is at its extended limit when the wheel is off the ground,
That may be true of the LS... but there are other designs, (at least in the past), where the lower control arm hit a stop that prevented further travel.
Either way... it is necessary to carry the sprung weight in some way so that the ball joint can be checked properly.
And if the aluminum control arms are that fragile... they have no business being on the vehicle in the first place. They are tougher than you think they are... otherwise they would not hold up to driving abuse and rough torn up roads, or potholes.
for no gain in diag ability