Help with preload for a ladder bar/coil over car

[68Coupe]

looking for help suggestions

[Mike Pearson]

What is the issue?

[Chevy55]

https://www.amazon.com/COMP-Cams-158.../dp/B000CIQ7UM

[GTX JOHN]

Does it go left or right off line?

This suspension always is a struggle for me for as simple a deal
that it is!

[CMcAllister]

Originally Posted by Chevy55

https://www.amazon.com/COMP-Cams-158.../dp/B000CIQ7UM

Not a bad read, a bit scholarly and maybe a bit dated as opinions, techniques and hardware has changed over time, even though the physics don't change. Also available for a more reasonable price from some other places. S&W for one, maybe others.

When chasing a problem and/or something has changed in the car, first look at the parts. How old are the shocks and springs, tires, rod ends. I've seen guys with cheap 10 year old SA shocks, beat up and leaking, dead springs and/or a bent housing, complaining that they can't adjust an issue out of the car. Verify the condition of the parts and pieces and/or update accordingly. This should be part of the regular schedule.

Weigh the car, 4 corners. Know where the weight is and what the preload (or lack of it) is. Keep track of it. If it moves around a bunch, something has worn out or bent. Good DA shocks are a necessity on a ladder bar car with decent power.

There are different ways to adjust the weights beside preload, but I would verify and baseline everything, then let the car tell you what it wants from there. Video and playback (30 fps min.) is valuable as well.

[68Coupe]

Car usually works well and leaves straight. Every so often it will tend to go right, and the rare occasion when it spins it goes to the right.

[Mike Pearson]

Originally Posted by 68Coupe

Car usually works well and leaves straight. Every so often it will tend to go right, and the rare occasion when it spins it goes to the right.

if the car is working good and goes straight most of the time then I would say maybe you are out of the groove when the car goes right. There are only a couple of reasons that a ladder bar car will go left or right at the hit. first is the rear is not square in the car. Second the front holes in the ladder bar mount are worn or elongated. Check both very carefully. Typically preload is not needed if the car is set up properly. My car I ladder bar and coil over. One other thing is I don't set the car up with the shocks on it. I have some struts that I made to go where the shocks mount the same length that I run the shocks. Set it up neutral with the struts then re install the shocks and set the ride height of the shocks exactly where it was with the struts.

[Hacksaw]

Check that the rear is square in the car, measure circumference of slicks and compare.

[Mike Rietow]

That's really not unusual OP, the rotation of the rear-end on low hp cars controls the dynamics of the chassis. A little pre-load takes care of that, but pre-load is a last resort. There's other avenue's besides pre-load depending on what we're working with. Do you have double adjustable coil-over shocks on the back of the car? What kind? How many clicks of adjustment?

Do you have double adjustable struts/shocks on the front? or single? or no adjustment up front?

[Mark Ugrich]

If it’s only on occasion , are both tires getting an equal burnout and heat? Out of groove like previously mentioned would make sense too.