Extreme rear end sway on the highway

I was going about 90 on the highway and i decided to change across 2 lanes , not real fast but both at one time, and as i did it my rear end started to swing back and forth.. not losing traction but causing the suspenion to compress back and forth on each side.. what do i need to fix this..Sway Bar?

Believe it or not, check your front ball joints. Any play in them causes the rear to want to follow the front end wander. This causes the rear to sway and the front moves around.

I was going about 90 on the highway and i decided to change across 2 lanes , not real fast but both at one time, and as i did it my rear end started to swing back and forth.. not losing traction but causing the suspenion to compress back and forth on each side.. what do i need to fix this..Sway Bar?

You should check your rear shocks for leaks.

Check to make sure the panhard rod is still there.

I would be looking to replace the rear shocks, with at least bilstein.

Sway bars are unlikely to be the problem, ball joints are also a long shot, you lack dampening, ie shocks, which are really dampers.

Z28

I vote for shocks as well.

While I don't want to be an ass, I have to ask..
What do you think happens when you trying weaving through two lanes at once at 90 mph?

A rear panhard bar also helps.

I vote for shocks as well.

While I don't want to be an ass, I have to ask..
What do you think happens when you trying weaving through two lanes at once at 90 mph?

I dont want to be an ass either.. but nobody was really around me and i was moving across 2 lanes towards my exit.. no weaving involved. just constant lane changes to the right

I'd start with the simple things and go from there.

Was the roadway rutted by heavy truck traffic? (most cars would get a bit "woozy" crossing those things on an angle at speed; normally this is an asphalt pavement problem)

Rear tire pressures equal and adequate for the tire size? (affects lateral stability back there)

Rear rims wide enough for the tires? (at least TRA minimum-width-compliant, not just that they were successfully mounted or present a particular appearance)

Bad PHB bushing, loose or worn bolt, oversize hole in bracket, missing or loose PHB brace, or structural damage involving the PHB brackets?

Norm