Car Bounces after 60 ft. What is causing this??

I have seen this same problem. If you look at the rear tire on the initial hit, it is compressing the sidewall to much. So what happens after the initial hit, is the tire rebounds and unloads the rear suspension. I would go up in air pressure. Also you may want to consider adding a inner tube if not using one already. The sidewall is basically too soft. On my friends 93 vert with a 26x8.5 Hoosier tire we run 14psi with a tube. That car at 3340lbs race weight will 60 foot in the low 1.30's and have had a best of 1.28 on the 60ft with this set up. When we looked at the video on his car with 12 psi, you could see the rim mash the sidewall almost all the way down to the track on the initial hit. Going to about 14 psi really solved the load/unload of the rear suspension. You may have to play around with air pressure to find the sweet spot for your combo. Also verify pinion angle, and you have to know that your instant center is set correctly before you get too caught up in other chassis adjustments.