Re: Help with preload for a ladder bar/coil over car
 

Resisting the urge to tell you to buy something, let's start here.
Assuming everything is square, and sitting on the tires, you would want the left front bolt out, and your weight in the driver's seat.
Now you would adjust the left bar until the bolt just easily slips into the hole.
That would be zero pre-load, and where you want to start.

Re: Help with preload for a ladder bar/coil over car
 

Pretty hard to do that with a coil over car

Re: Help with preload for a ladder bar/coil over car
 

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.

Re: Help with preload for a ladder bar/coil over car
 

Good point, Mike..I keep forgetting that S/S cars are steadily becoming GT car under the skin.

Re: Help with preload for a ladder bar/coil over car
 

Quick and dirty way to check preload (assuming you don't own scales): park the car on a flat floor, load weight into the driver seat to simulate driver weight, locate floor jack under rearend center section and slowly start jacking the rearend up. If you see the right or left tire raising first, you have preload on the other side. If you see the left rear tire clear the floor before the right side, you're likely going to be having problems.

Re: Help with preload for a ladder bar/coil over car
 

This way works perfect for me.I do mine on my full deck open trailer and it’ll go straight as a string