Need suggestions to improve 60ft.

[Robert Wilson]

I have been struggling with my 60ft times and would like suggestions on improving.

Current front end set up:
New V6 regal NA springs
AVO 3 way shocks set to 90/10
Poly Graphite bushings
All stock control arms

Rear end set up:
New stock rear springs
Air bags with HR spacers (1~2 psi)
QA1 single adjustable shocks
HR lower arms with Delerin Bushings
BMR upper adjustable arms with HR bushings in rear end.
All control arm mounting points in stock location
HR anti roll bar
Pinion angle -3*
2 year old MT 10.5 x 28 Stiff sidewall slicks mounted tubeless, not screwed to rims. Have varied tire pressure from 11 to 15 hot, seems to like about 14.
Wheels are 15 x 8.

Car weighs 3720 with driver.

Best 60ft with the current engine has been a 1.53. Best the car has ever done is a 1.48. Tried a 15 psi launch once with this engine and blew the tires off at the line...

In the first 2 videos, I tried to launch at 7 psi ramping the boost up to 23 psi at a rate of 30psi/second. Tire pressure was 14 and rear shock were set to 8 clicks up from full soft.
Video 1 was a 1.88 60ft.
Video 2 was a 1.68 60ft.

In the last 2 videos, I lowered the launch boost to 5 psi and ramped up to 23 psi at a rate of 15psi/second. Tire pressure was 14 and shocks set to 10 clicks up from full soft.
Video 3 was a 1.57 60ft.
Video 4 was a 1.59 60ft.


YouTube - launch vid 1

YouTube - launch vid 2

YouTube - 1.57 60ft

YouTube - 1.59 60ft

 

[Boost231]

your setup looks pretty good but im not a suspension guru. i would get some new slicks for starters.

 

[KEVINS]

A lot in getting and maintaining traction is setting up the front/rear suspension so the suspension loads the tires during the initial launch and so the car has good weight transfer to keep them loaded and this involves proper rear control arm geometry, shock settings, tires, torque converter, etc, etc..

On the 1.57 run the front end pops up waaay to quickly then drops but I can't tell if it's b/c the tires spin or what happended but either way slow the front end down.
From where the camera is located the rear of the car looks really high which really screws up the rear control arm geometry which screws up the Instant Center (IC) position so this doesn't do any good to load the tires and keep them loaded. From the factory the Instant Center can be behind the car and the higher you raise it the worse it gets. If you can just lower it as much as you dare to help correct the IC postion and get new rear tires and slow the front end down..

KS

 

[Robert Wilson]

A lot in getting and maintaining traction is setting up the front/rear suspension so the suspension loads the tires during the initial launch and so the car has good weight transfer to keep them loaded and this involves proper rear control arm geometry, shock settings, tires, torque converter, etc, etc..

On the 1.57 run the front end pops up waaay to quickly then drops but I can't tell if it's b/c the tires spin or what happended but either way slow the front end down.
From where the camera is located the rear of the car looks really high which really screws up the rear control arm geometry which screws up the Instant Center (IC) position so this doesn't do any good to load the tires and keep them loaded. From the factory the Instant Center can be behind the car and the higher you raise it the worse it gets. If you can just lower it as much as you dare to help correct the IC postion and get new rear tires and slow the front end down..

KS

I thought the front may be rising too quickly but wanted other opinions. I will change the shock setting to slow it down.

I have been reading about different G-Body rear suspension set ups an most agree the lower control arms should be level. Mine run up hill from back to front. I had thought about getting some QA1 coil over springs and trying to level the arms. Any thoughts on this?

 

[muzz]

Your first video looks alot like my car before I installed the hr rear bar.My front shocks are standard so the front end doesnt lift as quick as yours. Your car looks like it leaves harder than mine.I dont know about the rear control arms.

 

[KEVINS]

I thought the front may be rising too quickly but wanted other opinions. I will change the shock setting to slow it down.

I have been reading about different G-Body rear suspension set ups an most agree the lower control arms should be level. Mine run up hill from back to front. I had thought about getting some QA1 coil over springs and trying to level the arms. Any thoughts on this?

I also agree that the LCA's should not be pointing up and should be horizontal with the ground.
I just recently came out with a GN UCA kit that bolts-in which moves the IC to a better position to help cure the bad geometry and for best results the car needs to be lowered so the LCA's are horizontal with the ground.

You can see them here:
http://www.baselinesuspensions.com/kits/chevy.htm

KS

 

[steve hughes]

Robert. Give me a call. Steve

 

[Robert Wilson]

Thanks Steve, I will give you a call later today.

 

[lazaris]

First you need to video the car from the rear off on a 45* angle to get a little of the side as well. From what I can see from the angles you supplied, are your getting a bit too much squat in the rear and not hitting the tire enough. The front can be slowed a little as well but your getting more spin right at the hit. 14lbs in the rear of those tires are a bit high but I suspect its working better because your using a 15x8 rim.

 

[Robert Wilson]

First you need to video the car from the rear off on a 45* angle to get a little of the side as well. From what I can see from the angles you supplied, are your getting a bit too much squat in the rear and not hitting the tire enough. The front can be slowed a little as well but your getting more spin right at the hit. 14lbs in the rear of those tires are a bit high but I suspect its working better because your using a 15x8 rim.

Here are a couple more videos from another track from behind the car. The set up was the same as in the first videos (8 clicks on the shocks, 7psi launch, ramp to 23psi at 30psi/second)

YouTube - 1.62 60ft number 1

YouTube - 1.62 60ft number 2

 

[lazaris]

The car has too much squat and you really need a dbl adj shock in the rear to control the bounce.

 

[Nick Micale]

Maybe you have a converter problem instead of a suspension problem?