On the launch foot braking the car as soon as you leave the pressure on the strut bushing releases and causes the lower control arm to bounce off the pin. If the OEM lower bushing is ripped from tightening the lower arm pin nut when not in the center of travel or if using poly slip in bushings.
Poly strut bushings disintegrate while putting pressure on them foot braking.
Put your car in a forward gear and step on the throttle this sinks the pin. In reverse it comes out 3/8-1/2 inch. My son video taped this after looking at this video below in slow motion. The front wheels would shake as soon as they would come up. The car is tied down in the front to keep the car from lifting as much as it did. The flatter the car leaves the quicker it is.
Coil overs and hymns are what we are using now. In a street car everything OEM. Strut rods with swivels were the worse thing we ever saw. They don't keep the arm stable at all. Try OEM and adjustable without the torsion bar using slip in poly bushings lubed up as instructed. Pry back on the arm and you will see the strut with the swivel comes off the pin. The OEM rod with poly bushings almost comes off. OEM bushings and rod it doesn't move.
We switching to coil overs now on the Demon, Struts are used on the Firebird .
If your LCA’s moved around that much after you installed your poly bushings, you installed them improperly. Plain and simple.
Improperly installed parts fail, everyone knows that.
If you install your poly bushings properly, and pair them with strut rods that are the correct length, the issues you describe are simply not physically possible.
And without a strut rod installed, you can pry the LCA off the back of the pin with the OE bushings too. The rubber will fail. The idea that a rubber donut wrapped around the pivot pin positively locates the LCA is just silly.
I’ve run poly bushings and adjustable strut rods on the street for over a decade and tens of thousands miles on multiple cars. Guys on this board with poly LCA bushings have run their cars at autoX events, on road courses, and the strip without any of the issues you describe. That much movement would result in massive changes of the caster angle and the vehicle would be completely unstable. It just doesn’t happen when the parts are installed correctly.
A few decades ago you improperly installed a set of bushings. They failed. Just admit you did it wrong and move on. Everybody makes mistakes.
