[JMRacer]

have a suspension problem with my 69 Chevelle. I can't get the car to hook consistanly unless the rear tires have 11 PSI. Any higher PSI and the 60' times and traction become inconsistant. I'm using ET streets 15 x 12.5 x 28 which wrinkle up so much it's effecting my reaction times. They should be run closer to 15 PSI but the car will not hook at that pressure. The rear suspension has some inital separation at launch but not a lot.

Car details:

-Competition engineering 3 way adjustable shocks. Front set : 90 – 10 Back set: 50 – 50
-Moroso Drag springs. Front 47160 Back 125LB rate springs
-Hotchkis upper (adjustable) and lower control arms.
-Moser 12 bolt rear end (with the raised upper control arm mounting location) 4:56 gears. Pinion angle set 3.5 negative degrees.
-28” x 12.5" x 15” E.T. street @ 11 psi.
-Turbo 400 transmission with a trans-brake. Launch RPM 4200 on the rev limiter. The converter will stall to 5000.
-Car weighs 3370 LB with driver.
-Wolfe anti roll bar with no preload
-Engine has ~600 HP at the fly wheel

I'm looking into rear springs with a high spring rate and lowering the rear lower control arm mounting location to move the instant center closer the the rear end.

Anyone have experience in this area?

 

[Dave427]

UMI makes nice stuff. Changing the lower control arm mounts on the rear-end will help. UMI makes the bolt on kit for this. Here's a link.
http://www.umiperformance.com/4012?category_id=17
Dave

 

[Drag Radial]

How many passes on the tires? What type of burnout do you do?

 

[Big Squeeze]

What size rim? and those shocks need to go in the trash.....Good shocks will make a HUGE difference.............