Better Alignment & More with Aftermarket IFS ArmsPosted in How To: Suspension Brakes on April 19, 2017
Adding lift to independent front suspension (IFS) usually raises the suspension arm angles, and puts greater angle on the stock ball joints. Other effects can include suspension binding at full droop and loss of ability to adjust to optimal wheel alignment. Aftermarket upper control arms (UCAs) can help correct these geometries and compensate for added lift due to beefier or longer springs, leveling shocks, or coilovers. They may also provide a bit more suspension travel as well, and are typically stronger than the factory units they replace.
Whenever you change a control arm on the front suspension, or you change the ride height, it’s generally necessary to realign the front end. Often small ride height adjustments may only affect steering toe-in, as the effective length of the tie rods decreases when lift is added. However, when lifting IFS from stock, simply aiming for factory alignment numbers may not get the front tracking and stability you optimally want.
On most IFS, you lose caster angle as the suspension arms droop. Caster can be defined as the steering pivot angle (front to rear) when viewed from the side of the vehicle. This loss also occurs when you lift IFS and increase the suspension arm angles at rest. With a loss of caster you often experience more road wander and less steering return-to-center when exiting a turn. This effect varies by vehicle based on the specific front suspension design. Some are more forgiving than others to increases in ride height. Aftermarket UCAs typically have increased caster in their design to compensate for increased front end lift. On a lifted truck, greater caster (in excess of factory specs) does not significantly affect tire wear, so caster can be increased to regain better tracking and control on a lifted front end.