2 or 3 Link Suspension

The 3 Link suspension also known as 2 link suspension is not as complicated as the 4 link suspension type, the major difference is there is only one trailing bar on the left and right side of the car, two different mounting styles are utilized, the first is rigid mounted to the axle, the second is a free floating bird cage that allows the axle to pivot as the up and down motion as it is put through its range,  the rigid mounted style requires a pull bar or monte bar to keep pinion angle as well as the floater style suspension, the only difference between the two mounting styles is that a free floater suspension has less binding and the shocks and springs are held at a constant in relationship.  In the rigid style suspension the spring and shock mounted opposite each other in front and behind the axle are at the axles mercy as it moves up and down.

First off, the complexity of this suspension is not as grand as the 4 link suspension, many racers will start out using this suspension before graduationg to the 4 link due to the ease of trouble shooting.

The angle of the link bar controls forward bite, when the forward mounting position is higher then the axle mounting position, as the bar is leveled out bite is decreased using time, if the bar is more than 15-18 degrees uphill the side bite through the turn will make the car stick like glue, the problem you will run in to is that as soon as the car exits the corner, forward bite will fade fast, usually by mid straight on a short track, aprox 20 yards out of the turn, as the bar is laid horizontal the bite stays longer glueing the tires to the track as you go down the straights, forward bite is maintained longer.  the length of the upper bar will also dictate how fast bite is obtained as the suspension works through the turns.  A shorter bar will allow the changes to happen faster allowing faster bite. Generally the length of the bars will never be under 17" in length.  I recommend the use of shorter bars on short tracks, and a longer bar on tracks greater than 3/8 mile tracks, only because the movement of the suspension shouldn't be a split second transformation with higher speeds. This would make the car very unstable as you take the turn.

Normally the left side upper bar should be between 15-18 degrees uphill angle. The right side upper bar should be between 10-15 degrees to compensate for exessive suspension motion as the car is in the turn.

 

The control bar also controls rear steering: as the chassis rounds the corner, as the chassis starts tos roll in the turns the movement of the bar actually changes the axles positon and the rear geometry of the axle.  the left side unloads as the right side loads up as you enter the corner, as the bars move up and down the geometry length  of the bars change making the axle postion from left side and right side shorten and lengthen, this makes the left side move closer to the front of the car and the rear farther away, making the axle want to steer the rear end to the outside of the track, one way to correct or improve on the way the axle steers is to shorten the left side bar to compensate for over steer.  

 

The pull bar should be mounted with a down hill angle to allow the weight of the chassis to push down on the rear end when the transition of forward bite takes place, the use of a dampener spring, and shock is useful to help load up the rear end and hold the power to the wheels.

 

Now the best for last:   Do not make major changes when adjusting this suspension, the slighted adjustment can make major noticable changes, mounting holes are great but I recommend the use of slot driven adjustment mounts, this gains valuable adjustment space as one hole dimension to the next can make a larger change then what is needed.