tire shake with automatic

Our car is tireshaking on the hit. 3000lbs tubechassis with 2000hp blown alky and glide.The car gets up on the wheelie bars for about 10ft but the wheel paint leaves dash marks and the car usually heads right. We run the 4 link at 44 inches and 7 inches high. Inititially,the car did ok leaving at idle but now we have tuned it up and launching at 3500 its a mess. We tried increasing timing and rebound valving on the shocks and then started adding air to the tires. Went from 6psi to 7.25 without much improvement. At 7.4 psi it lit the tires instantly and hit the limiter. We use a 33*17*16 Hoosier Co7.The tires have about 25 runs with 20 of them being shakers. I was wondering if new tires might help. The car will run a 1.15 60ft shaking so I know we have the power,just need to keep the tires round.
Thanks for any suggestions.
Mike

 

we run that same tire on an altered with a blown hemi. 20 shut off passes isn't too many runs. how old are they? that would be the deciding factor with that many short laps on them. if they are less than a year old i would think you should be ok. also, do you run beadlocks? if so, let them down to let the tire slip a little. with a beadlock if you pump them up you will get more traction. i don't know if this will help, just my 2 cents.

 

I had similar problems when i ran a glide but i kept braking input shafts. Double check pinion angle and also 44" seems pretty short. 56" out and about 6" up seems right from my memory.

 

With a short 4 link like that if it DOES make it past 60' that thing will be a real handfull down track! That setup would usually mean LOTS of wheel speed down track. This might sound like a dumb question but have you thought about trying to launch higher or with MORE power? You're not going to dead hook a car like that and get it to run. Throw more at it and see if you can make it spin, then at least you can start looking at driveshaft speed and adjust accordingly.

 

I had the same problem with my car, shook and went right, retarded timing in first gear from 28 to 22, car went straight and 1.07 60ft, I leave at 4000 and have 1.95 first.

Matt

 

Overkill ,
is the 44" length , refered to the intersection of the upper and lower 4 link bar ? what 7 " referred to ?
Claude

 

Thanks for all the advice guys. Claude the 44 inch is the intersect point of the 4 link. Its actually 48.5 on my car. The 7 means inches above the ground.