|
Imagine if you will, the Saturn’s front axle arrangement. At a stock ride-height, the motor and transmission sit higher than the wheel centers – which means that the axle must angle downward from the transmission to the wheel. Yet, the points of entry at the transmission and the wheel must be straight (parallel to the ground) to allow proper rotation. It is for this reason that the front axle uses two joints - the inner "tri-pot" joint and the outer CV joint. Hence an axle assembly that consists of three zigzagged sections: a straight section that exits the transmission and enters the inner joint, the middle section that angles downward to the outer joint, and the outer section that passes through the wheel. And the function of the joints, therefore, is to accommodate the angular misalignment between the transmission and the wheel – in other words, the joints allow for the zigzag shape. And, of course, the joints are designed assuming that the angular misalignment will need to be accommodated. However, when the ride-height of the vehicle is lowered, the wheels are raised relative to the body of the car, thus bringing them into alignment with the transmission. This straightens the shaft assembly, replacing the zigzag shape with a straight line. In other words, lowering the vehicle removes the angular misalignment. But since the CV joints were designed with extra room to accommodate the angular misalignment, operating the joints in the absence of the misalignment allows slop within the joints. And this slop may occasionally be felt as a slight shimmy at certain slower vehicle speeds. Don’t worry: this phenomenon is not a durability, performance, or reliability issue, and it is nothing to be concerned about.
|
