trailing arms

[floppyfoot]

Exactly how do the adjustments of the lower and upper trailing arms do on a 4 link, stock metric type, effect the handling of a race car. Our upper and lower trailing arms are adjustable. The upper for length. The lower for length and height at the body mount. The uppers run toward the middle and down app. 17 degrees. The lowers are straight and are up to the mount on the body.

[floppyfoot]

Does anyone need more info here? We used to run a Toyota Celica in mini modified and was very successful with it. It had a 4 link stock setup but still had a panhart bar also. I ran the upper arms at 14 degrees down to the body, the right lower was level, and the left lower was about 1 degree up to the body with the driver in the car. They were not adjustable from this point but what we have now is adjustable. The panhart bar was level and ran to the right sode of the car. Just trying to understand what happens when any of these arms are moved.

[Bubstr]

Disregard the inward angle of the top bars, they work like any 4 link.

Time for some geometry. If you extend the points of the connecting arms forward, till they converge, then draw a straight line back to the rear tire contact patch from that point, you will have what is called an instant center line. Where this line is at the front axle compared to the center of gravity height will give you your anti-squat value. Anti-squat translates to on the bar, hike or separation or compression at the rear wheel.

If these lines, IC line and COG line met exactly over the front axle you would have 100% anti-squat that translates to neither on the bar or off. If the IC line was higher at this point, ( you would be on the bar separation or hike at the rear wheel), more than 100% anti- squat. Both sides work asymmetrical,(independently).

Here is where it gets tricky. Due to ride height or body roll, your bar connecting points change constantly. How ever your center of gravity height changes very little. This is exactly how you get roll steer in the corners. Left side ride height raises, increasing A/S value, creating hike or separation on the left side, that changes the wheelbase on that side, shortens WB and helps the car turn. Hope this helps you.

Warning, if some is good, a lot is better does not apply here. You can get so high of an A/S that it will hop like a bunny from the hike. Also what ever weight that is on the bar, reduces the ability of that spring/shock package to do it's job effectively.