Why one wheel locking first even after caliper rebuild?
 

My drivers front was locking first on the 930 so I suspected frozen pistons on the passenger side...... Sure enough they were, so I rebuilt that caliper and now the pistons move fine...

But now that drivers front tire is still locking first... Any ideas what might cause this besides a frozen caliper?

Did you rebuild both front calipers? If not, there is your answer.

Did you replace the brake lines? An old brake line on the left side could swell under pressure, causing the right side to lock.

-Boyo

Yes and yes...

but the wheel that is locking up is OPPOSITE the side that had the frozen pistons (which again, are fine now)... So even if I hadn't, this shouldn't cause that...

I know you already know this, but given the calipers are not badly seized [a given since you just rebuilt one or both fronts], the most likely next cause is corner balance out of whack.

If the driver's side wheel weight is 50+ pounds lighter than the pass side, then the driver's side wheel will lock up early.

Might be worth checking before you do too much more brake work.

Good point... I even checked the tire pressures which were within .5 psi thinking that might cause it... I may try and switch braqke pads from side to side... If any fluid impregnated the pads, might still do this too...

For a real quick check on corner balance: find the center point on the rack and jack the car up so the front wheels are off the ground. If it lists to one side, the rear balance is off. Do the same on the rear- just in front of the trans mount on the chassis- (careful to use a block of wood that does not mash the tunnel in)
You may have to disconnect the rear sway bar. Not too scientific, but you can do it quickly to see if you have a gross problem

if the tire was locking up before the rebuild then still after the rebuild i would have the front left checked for a flat spot, you'd be amazed at how minute of a spot can cause a tire to lock up.
my .02

Whe nI rebuilt my calipers the new o-rings did not allow the pistons to remain in position close to the brake pad. The result was I had to pump the peddle to get a the pistons to clamp o nthe pad. I am informed this is normal. Is it possible that this is happening with just one side - one side is grabbing properly and the other is not clamping down on the pad? The o-rings on mind wore enough after a week so I wouldn't have to pump the peddle. Maybe just a little more time is needed if the calipers are freshly rebuilt. There you go, my .02, worth about .01 these days.