I have subframe connectors, sway bars. And my car still fish tails on the express way. Is this all 4th gens because mine is a 2001 ss and my friends 95 lt1 supposedly does the same but he does not have my set up. Is this a bad shocks and spring issue or rear end

 

Depending how much power you're making and how many miles you have, it could be multiple things. Better springs, shocks, lower control arms and an upgraded panhard bar will be necessary if you're pushing much past stock power.

 

Not enough information.
What size swaybars? Is everything else stock? What kind of power are you making?
Balanced swaybars will help (32mm front/19mm rear, or 35mm front/21 or 22mm rear) go bigger in the rear and get more snap oversteer.
Good shocks will make the biggest difference in overall control, feel handling and keep the car stable. And by "good shocks" I don't mean oem replacements from autozone, Im talking sport shocks like Koni SAs (not drag shocks like QA1s, strange, afco, etc, that would be a nightmare).

 

I don't understand what this means, "fishtailing" on the
highway has never been a problem for me. Under what
conditions does it happen? Or is this really more the
"tramlining", "groove walking" that these cars are prone
to (esp. with fat tires and stock alignment settings)?

 

Under hard acceleration from a low speed when you loose traction the car's rear swings back and forth like a fish out of water, hence "fish tail".
Heres a vid for example:

 

Street conditions are hardly ever going to cooporate with you on that. Strip is a different story. There is so many factors that play into this. How much power do you have 800+ or are you just mashing it from a slow roll

 

When does it fishtail (just cruising along, accelerating, braking, cornering...)...?

 

Ummmm...Really? Who doesn't "fish tail" when you romp on the gas while turning the front wheels?? That mustang video is ridiculous...notice that the tires didn't smoke or leave tire marks? He wasn't spinning by the fact of high horsepower.

Now, if you are driving in the straight line and accelerating and you start swerving back and forth, you have zero traction. Could be tires, weight balance, wheel hop from worn springs/shocks.

 

As already mentioned, there are many factors that come into play here. Any one or combination of these things can contribute to handling issues.

Tires
Shocks
Control arms/bushings
Panhard/bushings
torque arm/bushing
alignment
etc

Plus, we need a better description of what is going on. I highly doubt you're just cruising down a straight highway with your back end swinging all over the place.

BTW - all fbodies have sway bars

 

I agree...more information is needed. The term "fishtailing" gets thrown about all the time, sometimes inaccurately.

 

I see he says it's when the rear wheels are spinning.

Spinning tires' grip is low and not especially directional.
Learning to respect the adhesion limit is probably the
answer.

 

That's no fun!!

Do that, and you can't sit at the bar with your friends, and say that your car has SO much power, it fishtails all over the place when I get on it.....

 

Speaking of my own, the biggest change in the *** getting silly when hitting it hard was installing rear control arms. I used the ones from Founders and there was a big difference in mine man. Doesn't kick out at all like it did and in the corners noticed quite the difference there too. *** end is much better planted in the corners now

 

Personally, I seem to chirp and/or get sideways for a moment when the tranny hits second gear going totally straight, but only if it shifts at or above 3k. It's been happening more often and has startled me, as I was getting on it, sure, but no where near flooring it. Tires have good traction too, probably a few years old. I'll have to look into getting rear lca's, they are pretty cheap.

 

Mine was doing that. I replaced a bunch of stuff at the same time so I cannot say exactly what fixed it, but in the rear I did springs, shocks, LCAs, and panhard. The parts I suspect that had the most effect were the shocks and LCAs, since my one LCA had a torn-up bushing which surely allowed for a fair bit of deflection. Even with totally shot tires the car feels far more composed on the road now and when the back end does lose grip on a 1-2 shift it stays straight instead of jerking to the right.

What shocks do you have?

If you get LCAs also, don't get standard poly LCAs. You'll lose rear axle articulation and can bind when cornering, over rougher roads, etc, making the back end more skittish and possibly ride rougher. I got the Founders 3 piece poly LCAs as a happy medium between articulation, low deflection, and ride comfort.

 

I have Bilstein HD's put on by the previous owner, according to paperwork it should only have about 15k miles on them, but the left one squeaks badly if I don't lube it at the top once and a while and I hear a sloppy shock noise in the same location, thought it could be something around the shock itself like a mount or something. So the 3 piece LCA's roughen the ride slightly?

 

Been there - done that and no fun. *** end was super squirrely on the highways. I wound up putting my stock LCAs with new Moog rubber bushings back on. I hated the bump over steer condition.

 

My over all ride smoothed out considerably after everything I did. I would say they probably do roughen it a little bit vs rubber, but then the Bilsteins more than made up for it vs the cheapo KYB GR2 shocks I had.

 

I don't like the sound of that, can you elaborate on that? Is it that way just driving normally on the freeway or under heavy throttle? I didn't have this problem before I installed SFC's, they just chirped before.

 

Do you have an auto? If you have an auto with 2.73's, you may not have as much spinning/sliding around when launching or under heavy throttle.