Complex vibrations - suggestions please

Recall the 2-1/2 months of work on the 97 Riviera this summer. Wow what a project. After all that, she's running GREAT but now I have some complex vibrations.

In hindsight the wheels should NOT have been re-balanced and rotated as there was NO PROBLEM with vibration before, plus they are OLD and cracking even though there's still 60% tread on them. I'm looking at the balancing data provided by the tireshop Tech and also the tread depth of each. Yes all these numbers are in a spreadsheet. Treadwise, they needed rotation but not at the expense of ShAkInG. Did I mention the tires being old?

There's a difficult to diagnose wheel vibration above 65 MPH and definitely at 75. It seems to be worse going around a turn on the highway. Could this be a steering issue?

The other problem is brake vibration. I need new REAR rotors and the front's turned. Get new pads while at it? Two or three shops didn't mention the calipers as needing attention.

What to go after first? the brake pulsation, typically slowing below 35 MPH? Then put the wheels back in their original position before rotation? I think the LF might be causing the problem.

Sorry for the long post.

-Ed

Have a couple updates and questions..


Wheel vibration

I need to be able to cruise at 80 MPH. One of two things can be done:

1) Switch LF & RF wheels so they're rotating the same direction as they were on the rear (before they were cross-rotated to front.)

2) Put all four wheels back where they were before rotation (the hell with tire wear.)



Brakes

Have purchased new Delco REAR rotors and pads. Can I do the REAR brakes at hone in the garage without issues? what about the parking brake? the calipers?

Haven't done brakes since my 1970 Chevelle.


-Ed

Autozone.com, repair guides has a pretty good how to on the brakes, I would put the tires back where they were before you picked up the shimmy, worth a try, no?