Miata Wheel Alignment

Written and conceived by Lanny Chambers

A precision 4-wheel alignment is the most important suspension upgrade you can make to a Miata. Without one, you will not get the performance your Miata can deliver. The factory "alignment" specs have entirely too much ±tolerance, and while every alignment is a compromise, the Mazda specs are biased heavily toward low tire wear on cars that are never driven hard. The large tolerance also makes the dealer's prep job less expensive.

The difference can be astonishing. Don't you want your car to behave the same way turning right as it does turning left? If performance doesn't impress you, how about safety? Fortunately, aligning a Miata properly is not difficult for a skilled technician, and is relatively cheap for the benifits gained.
 

Miq's alignment specs
While many owners have been happy with Miq Millman's specs on miata.net, I feel that while they should work well in autocross using very stiff DOT racing tires, they do not represent the best compromise for street use on street tires, particularly for a daily driver that also gets thrashed on Sundays. I started with a Miq alignment, then varied one parameter at a time until I got the balance I wanted. I don't like toe out, and I think street tires need more negative camber to work properly at comfortable, everyday pressures.
 

An alternative view
Here are my 1994 Miata's current alignment specs:

 

Rear   Toe: 1/32 inch (0°4.5' or 0.075°) IN per side   Camber: -1.5 degrees   Front   Camber: -1.0 degrees   Caster: 4.5 degrees   Toe: 1/32 inch IN per side

The parameters are listed in the order they should be set, starting with rear toe, which may constrain the other settings but is the single most important parameter for safe, predictable handling.

The car should be aligned with the driver's seat ballasted with your weight (and your customary passenger's weight in the other seat, too, if that's how you normally drive for sport).

On 7/7/00, I went to the above specs from 1/16" rear toe per side and -0.85 deg front camber, because I wanted the front to bite a little better with less throttle lift. The improvement was subtle but noticeable, just what I hoped for.
 

Match the alignment to your needs
My personal alignment goals:

• slight understeer under constant power at speed, able to transition to oversteer with slight throttle lift to transfer weight forward
• a good match with my power steering, OEM springs, Koni shocks set full soft and top perch, FM swaybars set to soft front/medium rear, and 3-season performance tires (currently 195/55R14 Toyo T-1S on OEM alloys)
• enough negative camber to wear the tires evenly across the tread under my aggressive driving style
• good highway tracking without tramlining or dartiness
• good steering feedback
• street use, not autocross

These goals were met, although the car still tends to follow road camber by drifting very gently toward the shoulder if there's much crown. Your goals may differ, but keep these points in mind:

• Adding weight (passenger, luggage, whatever) makes the rear camber more negative and the rear toe tend toward toe out. REAR TOE OUT IS A BAD THING in a Miata. It causes sudden, dramatic, often-uncatchable roll oversteer at the limit of adhesion, and can result in a spin. I recommend using enough toe in to insure that you'll never, ever see rear toe out. Yes, your tires may last a little longer at zero toe, but rubber is much cheaper than bodywork or hospital bills.
• If you drive hard in corners, more negative camber will actually help your tires last longer - regardless of what the dealer or the guy at Sears tells you - up to a point, say, -2.0 degrees for street use. If you don't ever drive hard, or if your tires start wearing on the inner shoulders, use less camber all around. Don't be afraid to experiment, once you understand these principles.
• Left and right sides must match. If a spec is unattainable on both sides, do the best you can then match the worse side.
• Maintain at least 0.5 degree front/rear camber bias.
• Too much caster can cause loss of grip near full lock in tight corners; 5 degrees is enough. If you have manual steering, you may prefer less caster for easier parking.
• Sacrifice rear camber to get the correct rear toe.
• Sacrifice caster to get the correct front camber, maintaining the 0.5 degree F/R bias.
• You can set front toe in your driveway without upsetting any of the other parameters, if you wish to play with front toe out for lightning-quick turn-in for autocross. If it makes the car dart all over the highway, well...don't say I didn't warn you.
• Start with both swaybars set full soft, if you can (assuming yours are aftermarket bars). Use alignment to get the basic handling balance you want. If it's close but not quite there, then use swaybar adjustments to stiffen the end that "grips too much." (I started with my rear bar in the middle hole to preserve the endlink geometry.)

 
Where can you get a precision alignment?
Ideally, look for a shop that maintains road racing cars. The technician should start by asking your personal goals and your weight (or offer to let you sit in the car on the rack). If you get an argument instead, keep shopping. A good shop may charge you up to $150, or even more in difficult cases. This is reasonable for the rewards you'll get. Some Miatas are harder and take longer to align than others, and an honest shop is entitled to charge more for spending the extra time. You won't be sorry.

An alert technician may notice that the suspension bolts have become stretched after several alignment procedures, and want to sell you new ones. He's not ripping you off: they do stretch, new bolt/nut sets are cheap, and will help ensure that the alignment won't slip the next time you hit a pothole. The latest bolts last a lot longer, too.
 
What about my M2? What if my Miata is lowered and has 17-inch wheels?
According to reports from owners of 1999-2001 Miatas, these specs work just as well on the M2. A lowered Miata may have different minimum limits for camber, since lowering itself induces negative camber; do the best you can. Wheel size has no effect.

What's next?
The Toyos are extraordinary tires, much more stable than the Bridgestone RE71s they replaced, with no tendency at all to follow rain grooves. I plan to try zero front toe, to see if I can improve turn in without promoting tramlining.

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