[tc]

A friend has asked me to watch/video his car and adjust his shocks because of loss of traction issues.

The car is a '67 Chevelle that runs high 9's with a good launch. It has a 12 bolt with stock location link bars. He installed an anti roll bar and coil over shocks.

I assume his car with a stock suspension has the driver side axle move away ( separate) from the car body and the pass side moves up, toward the car body on the launch.

Will the pass side separate with just using the anti roll bar?

Would I be adjusting the shocks opposite of each other ( using extension vs compression ) if the rear axle housing moves opposite directions from the driver side to the pass side?

[Scott65]

The anti roll bar "should" cause both sides of the rear to behave the same if installed and set up correctly. Start with a neutral preload with driver in the seat. Shocks should then be able to be used to control compression and rebound to fine tune the hit.

[tc]

Good, here is another question. When using drag slicks, should the tire show a crease/wrinkle beyond the 60 timer?

[Scott65]

Opinion only, to me that means add some air. Whats the tire pressure? (And on what size wheel/tire) Maybe a stiff sidewall is needed.

[tc]

Add more air is my thinking too. I think they are 29 inch Hoosier with the D06 compound. Not sure what he runs for pressure, or if the same pressure is used all the time because of the traction problems.

[slowbird]

Tire size and rim size effect air pressure needs

[tc]

10 x 29 tire, 10 x 15 rim, start on the high end, 11 lb sound ok? Car has some fiberglass, so it's lighter than all steel, factory interior items removed.

[Scott65]

Yep. Use a good gauge, and log the changes.

[slowbird]

11 sounds pretty low but start there and work up. My dad's GTO we run 14-15 when we run the Mickey slicks (29.5x10.5 slicks on 15x10 rim)

[Rob B]

Originally Posted by slowbird

11 sounds pretty low but start there and work up. My dad's GTO we run 14-15 when we run the Mickey slicks (29.5x10.5 slicks on 15x10 rim)

I use the same tire but in a stiff wall and found 13.5 to be the sweet spot on marginal to good tracks and have run 14-14.5 on a well prepped track. 3400lb car.

[tc]

He said when he contacted Hoosier, they said 9 to 11 pounds of air was the recommended range and he runs in that range. Should I convince him to run higher? If I see any wrinkle past the 60ft, like in an earlier video he has, maybe he will let me change the pressure. Right now I will be happy to adjust the shocks.

[Old Man Taylor]

I have 29x11 Hoosier's, and I run 10.0 psi.

[tc]

I did video the car with my friends iPhone and made shock changes. When my friend figures out how to rotate the videos for youtube, he will post them and I can share them here to ask questions.

These two videos are from a different source and look fine. These are for tire pressure concerns, let me know what you think. Stop #1 at 3-4 seconds, well beyond the 60 timer, look at the creases. Video # 2, try to stop at 1:13 to see the tire squish. 11 PSI, both runs. The underside view, forth run, was 1.42 60 ft, 6.20 1/8 et. # 1 vid was the first run, mid-high 1.4X 60 ft, low 6.4X et.

https://www.youtube.com/watch?v=h1WWgeV5GzA

https://www.youtube.com/watch?v=-ydYGEFw4ew

Also, driver side anti-squat ( separates ), passenger side squats.