I've got a full weight 98 Z28. It has a 12 bolt full spool 4.11 geared rearend. It has a fully adjustable Spohn TA with crossmember mount, LCAS with relocation brackets and panhard bar all fully adjustable. It has stock rear springs.
The front suspention is stock with the swaybar removed. I'm running MT 28"x15 DRS in the back and 4"X15 MT sportsmans in the front on Billit Specialties rims.
I've had the frame plumbobed and she is square. The only polybushing was on the LCAs where they mounted to the frame. It was been replaced by Derlin so she don't give at all.

I bought a set of AFCO DA T2s for the front with 300# springs and all the relocation/extention hardware on the front and AFCO DA T2s on the rear.
I can't get this car to hook. I usually hold the brake at the line and leave about 3500. I've got a Yank PT4000 convertor. And I've tried just nailing it off the line. Best time has been a 1.65 foot braking and the last time I just nailed it the passengers rear tire just shook and I had to let off.
front are set 12T and B 7 back are 22 top and 16 bottom
Car dynoed 445 RWHP and shes turned a best of 11.26. at 120mph. Can anybody help me out?

 

A vid would help but assuming everthing else is set up right, I would start the fronts at zero rebound and tight comp. The rears I would start at 50/50 with 17psi. I would also set the TA front to lowest point. Then make adjustments for the track. If it still comes loose then more rebound on the rears couple clicks at a time. This is also assuming the shocks are good.

 

If you bought them from madman he will help you dial them in. I used the sheet of paper that mine came with and adjusted from there. 3fingas is right though a video is going to help diagnose way better.

I found with my car that loading up the suspension by footbraking makes my car 60ft the hardest. I will load the car up get, light thre pre-stage bulb, then bring it up a little more until it starts to push the car to light the next bulb and back her down two hundred RPMs and let it eat!

 

Video + Madman = perfection.....

A lot of us guys started right where you are so if you can get some video of the car we can help you. Try to get a rear/side view as close to the car as possible. Don't worry about getting the light and time and all that right now, just focus on the car about 3 feet behind it and 3 feet in front of it. We need to see how the rearend separates from the car and how the front end rises.