What is a tie bar?
A tie bar stiffens the rear of the car by tying both sides of the lower suspension sway bar attachment points together. It is an additional add-on piece to a rear anti-sway bar. Some JBO members have installed a tie bar without the addition of a sway bar, though it is generally considered to be 'the next step' after installing an anti-sway bar.
A tie bar reduces suspension geometry distortion while braking and cornering. Under hard cornering, with a sway bar but no tie bar, you may experience lifting of the inner rear wheel around corners. If it doesn't lift, it at least gets light. With a tie bar, you eliminate a lot of the flex in the sway bar, and it will be tighter and help the wheels to maintain ground contact.
The tie bar is either mounted to the bottom of the axle at the ends (where the bottom of the strut mounts), or to the brackets that the sway bar attaches to.
Fitment on these bars is sometimes tight, especially clearing some aftermarket exhaust systems. The tie bar will usually fit but may touch the intermediate (or ‘over the axle’ pipe) on some custom installations, particularly on lowered cars.
For more information, check out this thread:
http://www.j-body.org/forums/read.php?f=3&i=122056&t=122056
