Originally Posted by bigins18
Call me stupid if you want but can someone explain to me in lamens terms what a 3 link or 4 link suspension is and the pros/cons for it on 35s soon to be 37s I found them using google but they dont give a very good description of what they are and how they function I need to change my short arm and was wondering if this is a good option cause short arms wont cut it for the tire size I need 37s to 40s would be nice
When you have coil spring suspensions like in the front of the cherokee you need a number of control arms to avoid the horizontal movement (front-rear and left-right) of the axle.
The stock configuration of an XJ is a 4 link +1, that is: two lower control arms, two upper control arms and a panhard bar (track bar). The two lower control arms limit the front-rear movement of the axle and the two upper ones avoid rotation. Track bar takes care of left-right.
Now the only direction that is possible is up-down, and is called suspension travel.
Problems start to come when you take the rig off road and twist the axles. What happens is that one side goes up and the other goes down, and the arms start to bind.
Since the control arms are linked firmly to the frame they will perform a semi circular movement and try to pull the axle to the rear at big angles.
If this happens when in twist, the lower left will pull and the upper left will push, exactly the opposite on the other side the lower right will push and the upper will pull. The result of this is an enormous amount of stress on the axle tubes and the rubber bushings.
To give a little more freedom to the axle you can remove one upper control arm and call it a 3 link, but the side you have removed the control arm will be less strong.
Long arms= longer radius and less semi circular movement, therefore less binding.