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Alignment Techniques: Tips for Getting a Great Alignment January 29, 2004 |
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By Michael Wright, Redwood Coast Miata Club
The Miata is a sports car that has good performance “right out of the box” with factory alignment settings. But to make the car really “sing,” I like to fiddle with key suspension settings in order to maximize the handling characteristics of the car. Alignment is probably the most important adjustment for getting the best out of the car. Camber, caster, toe … what alignment settings are right for you? As always, it depends.
Alignment settings will differ based on the equipment you have on your car. Specifically, the settings described relate to a 1996 M-Edition with KYB AGX 8-way shocks set to 3F/3R, stock springs and Flyin’ Miata performance sway bars set to full-soft on each end.
What I do is this: (a) Set camber to what will give proper tire wear at my intended driving levels over the next six months; (b) Give up as much caster as necessary in order to get the desired camber; (c) Set caster to something between 3.2* and 4.5*, depending on how quick and light I want the steering to be; and (d) Set toe to the something between 1/16” toe-in and zero, depending on how much tracking I want to maintain. Let’s look at each of these settings in more detail.
Camber primarily dictates how hard you can corner and helps ensure balanced cornering. It needs to match your driving style and how hard you corner. It also impacts tire wear and should be set to the range that yields good wear over the life of the tire. Typically, I’ve used camber settings between negative 0.8* and negative 1.8*.
If your driving style tends to be hard on the gas through corners, you may benefit by having a bit lower camber bias from front to rear (such as –1*F and –1.3*F). If you typically drift through corners and maintain your momentum, you may benefit by having a somewhat higher camber bias (such as –1*F and –1.5*F). With respect rear camber, -1.8* can accommodate higher cornering loads than –1.2*, which in turn allows higher cornering loads than –0.8*. Typical settings range from –0.5* up to –1.8*.
Caster is what helps give that “on center” feeling to the steering. In conjunction with the toe settings, it helps dictate the level of turn-in and responsiveness of your car. Caster is adjustable on the front end only. Typical settings range from 3* to about 5.5*.
Toe helps a car track straight. A little bit of toe-in can help the Miata remain stable through cornering and over undulations in the road. Toe-out helps that end of the car turn more quickly; at speed, this can be dangerous. To guard against this, many recommend a slight toe-in setting on both ends of the car. Mazda also designed suspension bushings to induce slight toe-in under load, to resist such toe-out conditions.
The Miata is extremely sensitive to caster/toe settings. Together, caster and toe up front work together to tune the turn-in and steering responsiveness. If you use a lot of toe-in or set caster very high, you will get more-stable highway handling at the expense of steering quickness; too low, and the car will dart to the side with very little steering input. Consider the following. Keeping camber unchanged, I set 1/16” toe-in per side and caster to 5.5*. This made for a fairly boring and sedate ride, with no surprises. Setting to 1/32” toe-in per side and 4* caster yielded much quicker turn-in and more-responsive steering. Using zero toe and 3* caster gave extremely quick steering feel and an ability to quickly turn into corners … to the point that a sneeze could cause the car to jump halfway into the next lane if I was not careful.
The “best” settings depend on the equipment on your car, your driving style and the roads you typically run. Currently, I am using –0.75* camber, 3.7* caster and zero toe up front, combined with –1* camber and 1/32” toe-in per side on the rear. Steering feel and transitional response is very high, allowing for quick turn-in and good control; yet, it is balanced enough for highway cruising while avoiding wandering between lanes. Whatever else you may do, ensure that you sit in the car during an alignment or have the car “ballasted,” given that alignment settings can dramatically change the moment you sit in the car.
Interestingly, what I’ve ended up with is a well-balanced combination of settings that allows a single change on one end of the car to change the car’s handling character. Now, boosting tire pressure by +/- 2psi on one end can dial out oversteer or understeer; as can stiffening the sway bar on one end by one notch. As well, simply adjusting throttle input during cornering helps adjust the car’s balance in that corner. To me, that’s the perfect alignment.
