The angle of the third (or...
The angle of the third (or upper) link helps determine the amount of antisquat. The greater the angle put into the bar, the more A/S effect. The addition of a pull bar does not change the A/S effect. It only cushions the application of the engine torque to the rear wheels.
Adding angle to the third link will increase the A/S effect, but this has its limits because the effect is reversed when we decelerate and brake into the corners. Instead of transferring load onto the rear tires, the reverse means that we reduce load on the rear tires when entering the turns, which can make the car very loose. Usually a 6-8 degree angle is sufficient to cause the desired effect without being excessive. If more A/S effect is needed, lower the third link and/or raise the lower trailing arms while maintaining the angles of all links.
If the third link is positioned laterally halfway between the centers of the rear tires, then the amount of load being applied to the rearend will be equally distributed between the rear tires upon acceleration. They will gain vertical load in equal proportion.
If the third link is moved laterally and closer to one side of the car, more of the vertical load will be applied to the closer tire. In this way, a greater load can be applied to one of the rear tires upon acceleration if that is a desired goal.
So, if the overall load on the rear tires by using A/S is no more than it would be without using it, how does the car gain traction by using A/S? Past experience indicates the car definitely can benefit from A/S to get better bite off the corners, so how does that work?
The amount of weight, or load, transfer that occurs during acceleration is determined by three things: 1. the magnitude of the accelerating force, which cannot necessarily be changed with the same motor/gear combination; 2. the length of the wheelbase-again not a variable; 3. the height of the center of gravity of the car. The last item is influenced by A/S, and load transfer is affected by it.
A higher center of gravity means more weight is transferred during acceleration off the corners. If the car squats during acceleration, the rear becomes lower, and the overall center of gravity is then lower in the car. A lower center of gravity means less weight transfer and less vertical load that is applied to the rear tires upon acceleration. By using A/S to keep the rear of the car from squatting, the center of gravity remains higher, and therefore more weight will be transferred to the rear tires.
Another way to increase rear load is through the aero effect of keeping the rear of the car higher and, along with it, the rear spoiler. A higher spoiler usually means a more efficient flow of air over it and more rear aero downforce.
Antisquat helps the car gain more vertical load on the rear tires, not from its own mechanical effect, but by helping to keep the rear of the car higher. Moving the third link laterally will allow you to determine where the added load will be applied between the rear tires.
The following are methods of further loading the left-rear (LR) tire upon acceleration: Use rear spring split with a softer right-rear (RR) spring; use a shock on the LR that has a higher compression resistance than the RR shock; and, as stated above, move the third link to the left.
The ideal load distribution on the rear tires for maximum traction off the corners is to end up with an equal load on each tire during acceleration. If the RR tire has more vertical load due to the weight transfer from the centrifugal forces that move weight from the left side of the car to the right side, there is a definite need to cause a shift in weight from the RR tire to LR tire upon acceleration to equalize the load on the rear tires.
If the rear tires are made to be almost equally loaded by using the spring split method, then the LR tire may be overloaded by moving the third link to the left, mistakenly ending up with unequally loaded rear tires and less traction. Be careful how far you go to try to get more traction-you might be going backward at some point in the process. Antisquat is just one of the ways to fine-tune your setup after you have processed all of the basic elements of a balanced chassis.