How to adjust a 4 link suspension

1. Make a simple side view drawing of your car. You will need to show wheelbase, height from ground to center of rear axles, and the dimensions for the 4-link axle bracket holes.
2. Draw a vertical line through the front axle. Put a point on that line representing your vertical center of gravity (around 22" above ground for most production cars).
3. Draw a vertical line through the rear axle. Put a point on the drawing where this line intersects the ground.
4. Draw a line connecting these two points. This line will represent the boundary for 100% anti-squat.
5. Now you must draw in the front four-link bracket holes. Most kits have brackets with multiple holes, and the bracket is usually set at 24" forward of the axle. Draw lines between the front bkt and housing bkt to represent the 4-link tubes.
6. Extend these lines forward until they intersect. The intersection point is called the Instant Center of the rear suspension. It is the point in space that the suspension moves about.
7. If your instant center is on the line in step 4, you have 100% antisquat (the car won't squat when you jam the pedal).If your IC is above the line, you have greater than 100% anti-squat, which will really load the tires. If the IC is below the line, you'll have less than 100%.
8. IF the IC is below the line, you'll have to reposition the four-link tubes (or the front bracket).

You can see here that the vertical positioning of the forward bracket is critical. If it is too low, you'll never get the IC on or above the anti-squat line. I used a Competition Engineering kit, and it didn't have good instructions on the vertical positioning. So, I did this layout to determine the IC location, and thus the vert pos'n of the front bracket.
Equally important is pinion angle. Just Strokin gave an excellent description on this just a couple of weeks ago. Good luck.

Thanks for the info. I would to learn more about pinion angle and adjusting for a pull to right or left.

First thing you need to do before trying to tune anything is if all of the bars are the same length make all of them exactly the same if the uppers are short make them the same R&L as well as the lowers R&L. The lowers set the wheel base the uppers set pinion angle and pre load. The right upper sets any type of preload you want, it is the only bar that you adjust leave the other three alone when tuning the car. The others should be set netural. After getting the bars the same length you need to put them back in and get the car square front to back and corner to corner. then let us know how it drives.

Remember when turning the right upper bar I try one "flat" at a time and keep track of where you move and the results.

Thanks for your help. I have set up the bars as you explained, then had to shorten the upper bars to set my pinion angle. I was told by TCI the pinion angle should be 0-2 degrees down. If this is correct my pinion yoke will hit the track bar. It barely clears at 3 degrees up. I am measuring at the face of the yoke with the car on all 4 wheels. In relationship to 90 degrees with the ground. Is this correct? TCI says there is a clearence issue but should be able to get 0 angle. Any advise will be helpful. Thanks John