Jeep Suspension 101
Chapter 1
Introduction
The Rubicon suspension shares almost all its components with every other 2003 TJ. Besides the high pressure shocks and stiffer springs, it's a TJ under there.
The TJ has a 5 link coil spring suspension on the front and rear. In this chapter we'll deal discuss the common items on both ends. Steering related items will be addressed in a later chapter.
The phrase 5 link refers to the number of locating items between each axle and the frame. These consist of 2 upper control arms, 2 lower control arms and a track bar. Each axle is also attached to a pair of shock absorbers, a pair of coil springs, and an anti-sway bar. These do not locate the axle, but affect ride and handling.
Control Arms
The control arms position the axle fore and aft. The geometrical relationship of the length and relative angles of the control arms creates the path the end of the axle takes up and down as the axle articulates. This is not a vertical path, but somewhat curved. The relative length of the control arms also establishes the pinion angle. Stock TJ control arms are fixed in length. Cam bolts installed in the bushing on the axle end of the lower control arm will change the effective length slightly. Stock control arms are made of stamped steel in a u channel configuration for strength, with rubber bushings for compliance. We'll discuss control arm configurations in later chapters.
Track Bar
The track bar (also called a Panhard rod after its inventor) is the 5th link in the suspension. It is connected between one end of the axle and the frame and centers the axle laterally. Because the track bar is a fixed length, as the axle moves up and down it will also move side to side slightly. In street applications this is not a problem, as the range of movement is relatively limited. In Jeeps with significant lift, this needs to be addressed.
Coil Springs
The springs establish the ride height of a Jeep, given that the shock absorbers are long enough. While the leaf springs in a YJ or CJ position the axle laterally, the coils in a TJ simply support the vehicle.
Shock Absorbers
They do what they're called. Shock selection is important in off road applications to provide proper jounce and rebound through the full range of suspension travel.
Sway Bars
Actually anti-sway bars. They improve street handling by increasing roll resistance. They also limit flex. Most 4 wheelers install front sway bar disconnects for use off road. The decrease in roll resistance is usually not a problem at low speeds, while the gain in front flex is significant. Some Jeepers also disconnect the rear sway bar. While the maximizes flex, it results in a very tippy Jeep. This is not for the inexperienced or the faint hearted.
