Severe oversteer in my 01, but not in my 99. Critique my suspension mods
 

Hi all. I have two fbody camaros. The first is a 99. It has eibach lowering springs. 1.5" I think. Kyb shocks, and big eibach front and rear sway bars, and strut tower brace. Founders rear control arms And drop brackets and 275/40/17. This car handles like it's on rails. Completely controlled oversteer. At no point does it ever snap the rear uncontrollably.

The 01 SS I just bought is slammed. Unknown springs 2-2.5" drop. Kyb agx shocks, stock sway bars, aftermarket adj rear control arm and panhard bar. Rides on vette 285/40/18.

The 01 loses control every time. Constant oversteer. I've done a 360 on accident because the rear keeps snapping around.

Both m6 cars. What gives? Is the crap springs on the 01 causing this? Or is it the sway bars on my 99 that make it so good? Any opinions?

What kind of tires on the 01 ss? Also, how many mileage?

99 113k miles
01 197k miles

The 99 has bald rear mismatched tires. Doesn't matter what I put back there, it doesn't lose control.

Idk what tires are on the 01, but they have more tread then the 99

Do both cars have the same rear gearing?

Likely the crap springs (probably sportlines) on the 01 that is causing snap oversteer. That or if you have poly bushings in the rear control arms they could be binding.
Have you tried adjusting the rear shocks at all?

342 on SS 373 on 99

342 SS 373 on 99

I dialed shocks from 8 to 5. Didn't help. Gotta be springs

Did you just stop at 5? Keep trying to adjust lower. Make sure your tire pressure isn't higher than 30psi in the rear as well.
Im also still betting that the rear lca's are binding too.

The rear lower control arms are not poly poly. It's got a rod end at the axle side. From my understanding, those shouldn't bind right?
I also hear clanking that worries me that very well could be the problem, however a search shows me that the noise im hearing is common... Though something is up. Sounds like it coming right from wheel or control arm or shock spring, but when I get under they're everything is tight

Thats better, but the poly side can still bind.
When does it clank? Over bumps? If so it could be the rod ended control arms, rod ends will make clanky clunky noises. Could also be a lot of other drivetrain related things, like the diff or u joints.
Also I never asked, when you say severe oversteer are you talking about in regular driving conditions or when pushing the car hard around turns? If its in regular driving conditions then something is seriously wrong, and probably drivetrain/rear end related. If its just when pushing the car hard around turns then its more likely suspension related.

My guess is those springs, 197k on the car, but how many on the shocks?