Custom Swaybars
Rear Bar
The swaybar usage for the Z race car will be different than the stock swaybar setup for two reasons. First, I wanted to mount the rear swaybar onto the upright suspension supports as some of the older aftermarket bars were designed. The newer ones are attached just behind the seats, ahead of the rear axle, making the bar long, and the arms extended. With the bar moved behind the axle, and by attaching the bar to the uprights, I have shortened the bar and arms considerably, thus reducing weight and bar diameter, and still get the same stiffness as I would have using a larger bar in the stock location. One of the bars I used came out of an '80s style Alfa Romaro front swaybar. It is essentially a straight (not less than 26" on the straight portion) bar that is bent on both ends at about 80 degrees. The arms were too long, so I cut the old ends off, and redrilled the new ends. This bar is 24mm in diameter. The bends occur just outside the edges of the uprights holding the rear lower control arm pivot point (or in my case, immediately outside the edges of my upright "plate" ; see "Uprights"). It appears the bar was made for this application, and with new polyurethane bushings throughout, the rear assembly is complete.
After racing the car for part of a season, I found that the car understeered just a bit, even with slightly softer compound tires in front. To remedy this problem, I chose to go with a larger rear bar, rather than go with a smaller front bar. Being the Alfa front bars are only one size, I had to find another donor vehicle in which to get a bar from. I found that the GMC/ Suburban truck front sway bars where as close as I could find to match the dimensions needed for the rear. It was essentially the same as the Alfa bar in shape, with the exception of the arms not bent at enough of an angle to be aligned over the suspension arm links, and also in that the bar is 27mm vs the 24mm Alfa bar. A strong press was used to increase the bend of the arms from about 60 degrees to a needed 85 degrees. Now the bar will fit after I remove the old ends, and redrill the new ends to match the suspension arm links. Both front and rear bars will now be the same diameter.
Note: After the car was completed, I experienced problems with the U-jointed half shafts, and swapped them out for some CV jointed half shafts. In doing this, I found that the above swaybars, and/or it's present location, interfered with the outboard CV joint and boot. To remedy the problem, I removed the bar, and bent each of the arms on the bar enough to clear the joint, and then reattached the bar.
Front Bar
The front bar was a little more complex because of the increase in caster I have built into the front suspension by moving the front lower arms forward by about 1-1/4" (which is explained in the caster section). Without this move, a stock bar could have been used. In fact, a stock bar could be used anyway, if you want to move the attachment points on the frame rails further forward to match the same lower arm move, but this, in my opinion, would be a risky move, considering the strength of the stock bar mounts compared to the beefing up needed on the new location in terms of preventing any cracking or breakage of new mounts due to the high twisting loads of racing on a very stiff swaybar and chassis. The stock bar mounts are reinforced inside the frame rail from the factory, and I fear any welding of new mounts and reinforcement (unless done just right) will result in a failed mount quite soon. Anyway, with this in mind, I began looking for a bar that would be essentially straight for a distance not less than 30", with a bend on each end (much like the rear bar, only bigger). I found 2 such suitable bars that could be used for the front of my Z. They are found on the early '80s Buick Riviera, and Cadilac Seville front sway bars. These vehicles also came with two different diameter bars of same shape, thus giving you a restricted choice on bar size. I chose the smaller of the sizes (27mm vs the 30mm) being the car has been lightened. As with the rear bar, the arms on these bars are bent at roughly 80 degrees, but now the bar crosses directly over the link holes in the lower arm, whereas the stock bar missed the holes by roughly an inch. As short as the links are connecting the bar to the control arm ( the links are about 1-1/2 long), this one inch became too much of a misalignment. I tried to straighten out the Z (an aftermarket 30 mm) bar I had, with a 20 ton press, but the only thing I bent was the arbor plates. Again, like the rear bar, the arms on this new bar were too long, so I cut the ends off, and redrilled the new ends to accept the suspension link bushings. The reason I omitted adjustable links, were again because of the shortness of the links (due to the high degree of lowering of the body for competition purposes). With new polyurethane bushings throughout, the front bar is complete. The front bar is 27mm in diameter, and has shorter arms than a stock bar, thus increasing its effective diameter even more over a stock bar. As with the original bar, the bends occur just past the mounting brackets on the frame rails and appears to be made for this application.
This bar is 3mm smaller in diameter than the aftermarket 30mm Z bar I was using. But with the 1-1/4" shorter arms, the new bar will be about 5% stiffer than the Z bar was.
Front bar dimensions: 40" long, 7.75" arms, with a middle section not less than 30" long.
Rear bar dimensions: 35" long, 8.75" arms, with a middle section not less than 26" long.
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