Stock bars

Bushings

For autocrossers

Several years ago, I had ADDCO make a 1 & 1/8" bar for the SHO rear suspension. I calculated this bar to have a stiffness of about 700 pounds/inch deflection, which would mesh nicely with the approx. 350 pound/inch 24mm front bar. Some of the front drive handling gurus like Multimatic (builder of the Canadian Firehawk series SHO's), felt that a 1-to-2 front-to-rear roll stiffness ratio would perfectly balance the SHO. 

I needed a good test for this bar, so I ran the SHO at an autocross in Denver, doing the first four runs of the course with the '89's stock 26mm rear bar. After my competition runs, the best of which was about 59 seconds, I went to the pits and changed to the larger rear bar, leaving the rest of the car's setup unchanged. After the last run group, we did fun runs. My first fun run on the larger bar was 0.6 seconds faster than my fastest time earlier that day. Tho that's only a 1% improvement, autocrosses are typically won and lost by considerably smaller margins. 

The car was much easier to drive, understeer was virtually non-existant, and it was much easier to pivot thru tight corners. It was also easier to keep the rear end in line with the loud pedal. The end links did indeed bend, but that's  because they were too short. I've since corrected that problem. 

In the past several years, I've transitioned from autocross to road race and Solo Trials, both much higher speed venues. For these, the larger bar has required some fine tuning. In high speed corner entry, the larger bar tends to transition too quickly as the body begins to lean, tending the chassis to snap oversteer. Snap oversteer is nearly impossible to recover from, and it once put me in the weeds at Stapleton's road course. I adjusted to this by overslowing prior to the corner and tip-toeing thru the entry. Midway thru the corner, I could start to add throttle and manage the oversteer by judicious throttle application. This was definitely not an optimum situation, as an oversteering car ("loose" in NASCAR parlance) may be slightly faster in the hands of an expert, but it requires lots of attention and is tiring to drive. Besides, I'm not an expert... 

I played some more with my CAD models of the SHO suspension, and plugged some test cases into the CARS program (CARS is a race car suspension design package). What I found was that I either needed a softer rear bar, or, I needed to allow the body to lean 6 or 8 degrees before the rear swaybar started to work. I tested this by just leaving the end links loose, which actually worked quite well, but the rattling drove me nuts, so I fashioned some longer links and used the extra length to add some fairly heavy springs on either side of the swaybar eyes.  These springs allow the suspension to compress somewhat before the swaybar comes into play. The end result, no more snap oversteer.

Police package front bars