Ok guys heres the problem,

On a smooth road my car rides nice and smooth but seems to tack left and right alittle in the rear but its nominal and very driveable. Now when the road hits any bump the car rattles and shakes real bad and the rear kinda slides. Its awful. The rear is making a fairly load hmmmmmmmmmmmm noise lol. On bumpy roads the car is scary to drive because it sways so much. Whats goin on .

 

Heres an update the car has much bigger tires in the back than in the front, not sure if that means anything but im brand new to rwd first one :-).

Also on smooth roads the car corners like a monster, no hesitation or slippage at all. But when it hits grooves in the road or bumps / indents its scary.

 

Well these cars are stiff, but I'd check to make sure that there aren't any loose suspension components or anything highly worn

 

A little more information might be helpful. The car? How many miles on it? How wide are the tires? Generally, wide tires will tend to "trammel", or follow the irregularities, no matter what the car. Has the alignment been checked recently?

Mileage and past maintenance may provide some clues....

 

Im not sure the exact size but they are pretty meaty tires in the back.
The car is a 95 with 78k miles on it. Whats that humming noise its making? And the shocks look new.

 

decride the humming a little better if possible and when its it doing it

 

well its odd noise actually kinda like a bearing if i would guess. Its a deep humming noise happens through all gears louder at higher speeds

 

I had the exact same problem when I installed my 255 DRs. I think it's more about having more contact with the road, but wider tires do that, so it's all correct. I only mention it since my 255s aren't that wide compared to stock.

At first I thought it was my sway bar, since the rear wasn't on at that point in time, but installing it didn't do one bit.

However, I'd put in some new bushings if you haven't. Get polyurethane ones.