Before the rules changed, the only way to get more negative camber from the front suspension on a Spec Miata was to lower the car. It worked, but it also could put you down into the bump stops in hard cornering and abrupt suspension moments such as driving over kerbs.
Changes in the Spec Miata rules now allow the use of offset upper control arm bushings in the front and the Bauer Suspension extended lower ball joints. Both options allow for more negative camber without having to lower the car more.
NASA rules allowed the lower ball joints first, and that’s what I used on my last car, so I elected to go with them again in my new build. I still believe they’re easier to install than upper bushings, because I don’t own a press and there’s really no way to install the ball joints incorrectly. The upper control arm bushings require a press and their offset bolt holes must be perfectly aligned with each other for the suspension to function properly.
Unlike bushings, the ball joints have moving parts, so they do wear out. I got two and a half seasons out of the last set, but they should have been replaced after two seasons. If you have significant contact, you might consider replacing them, too. We found the problem when doing an alignment. With the front wheels off the ground, the wheel exhibited vertical play. On the track, the slop made it difficult to transition smoothly from yaw at corner exit.
The job itself should be fairly self-explanatory as you pull things apart. It’s possible to do the job without removing the front rotor or caliper. The ball joint can be a bear to detach from the lower point on the steering knuckle. A ball-joint separator tool or a big freaking hammer are vital tools for this job. Here’s how it went.