I like the 3-position adjustable feature in the bars. I also like the thickness of the bars ST makes. When I opened the box and saw the bars the first time, I was quite amazed how heavy a 1" front bar could be. Compared to the factory bars, the ST front bar looked very thick and the stock rear bar looked more like a cable than a bar.
Installation was straightforward and the most tedious work was to remove/install the big plastic undercover. At first, I did not use the proper gel-like lubricant and used high-pressure molydenum grease instead. Result was squeaking noise and binding suspension. Using the proper lubricant later fixed the problems. It is best to barely tighten the end-link bolts and drop the car on the ground before tightening the nuts again fully. Otherwise, the end-link bushings will be "loaded" all the time. One problem with my ST rear bar (the later version seemed to have the problem fixed) is that the surface for the end-link is not parallel with the end-link. This creates a potential problem which makes the bar hitting the metal part of the end-link. What I did was inserting a spacer between the bar and the end-link for clearance. Remember to check the tightness of the end-link nuts after driving the car for a while. When the bushings found their most "comfortable" position, the end-link nuts can be tightened a bit more. That happened to me every time after I changed the bar settings.
I noticed the first difference the bars made when I drove off my slanted driveway. Whenever I drive off the driveway at an angle, two diagonal wheels will be pushed up by the slope. With my hard-top on in October when I installed the bars, the twisting force on the chassis was so great that the hard-top gave an unpleasant bursting sound. It sounded like the hard-top was being twisted into pieces. For cornering, the bars help reduced body roll by a great amount, much greater than by the ST springs. Contrary to what many people think, the bars DO degrade ride quality. The car is very sensitive to bumps that get run over by one side of the car and make the car rock left and right. I am not talking about rocking like an old American car but a continuous change in "banking" in response to every tiny bump on the road. On the other side, it is still possible to scratch the front subframe on a speed bump because the bump pushes both front wheels up at the same time, ignoring how stiff the front anti-roll bar is. The urethene bushings that came with the bars are way much stiffer than the stock rubber ones. and resulted in a little bit more suspension binding with the ST bars.
About autocrossing performance, the bars help a lot. With the Tokico shocks (installed after the bars) set to maximum stiffness, I was able to go through a set of slalom with incredible speed and stability. See my hobbies about the autocross event. I also tried increasing the rear bar stiffness in some races and the result was that I could get a rear wheel off the ground. A 3-wheel stunt is not a surprise for VW and many FWDs where weight distribution on the rear wheel is only about 1/3 of the car's weight. But for a Miata having about 1/2 of its weight on the rear wheels, getting a rear wheel off the ground when cornering is not easy, although in my case, the shorter shafts of the Tokico rear shocks contributed somewhat. Just for my curiosity, I tried out the stiffest setting for both bars. It was definitely too stiff. Although the car seemed quite balance in a G circle, sudden jerk on the steering wheel is very likely to overload the outside front tires because weight shift between the front tires were way too much and too fast.
During the 97 review, I liked the handling of the car with the front/rear ST bars set to medium/medium or medium/stiffest depending on the autocross course and alignment setting. However, during the 98 autocross season with a very tough competition on a very sticky airport runway as our new race site, I totally reconfigured my alignment, bought much-stickier tires and had to change my ST bar settings. With the reduced front camber for more grip on bigger corners, the car is less responsive in tight corners. The added front grip requires a stiffer bar setting in the front and I'm now more comfortable with the stiffest/medium front/rear ST bar setting.
Unfortunately, as with many people with 1"+ front anti-roll bar matching with soft springs, the chassis-side bar mounts were sheared off the chassis. The broken mounts were removed from the chassis by drilling the welds out. Originally, I thought about fitting a huge aluminum block in place of the current arch-like mount. However, the passenger side mount has the power steering cooler hoses in the way as shown in the right most picture below. We decided to just have the cracked mounts welded and filed to fit the bolts and chassis for now. Since Terence and I got ourselves a welding machine, I will weld in some reinforcement mounts later.
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Tokico Illumina
5-point adjustable shocks
