SuperMiata / 949 Racing 89-05 Miata set up tips
All content on this page copyright Traksport LLC 2015
Updated June 18, 2015
Disclaimers: Performing any modifications to your car based on advice from this FAQ page is dangerous, might kill you and and kill a kitten somewhere. IOW, read, assume, implement at your own risk (don''t sue us if you mess your car up and crash)
These settings may not be compatible with your vehicle, driving style or conditions.
The race alignment shown below are the maximum performance settings to generate the best balance of turn in, steady state lateral grip, braking grip/stability and power application in competitive type driving environments. The bias is towards steady state lateral grip as that is what makes a Miata fast more than the other facets of it's performance envelope.
The Race Alignment assumes:
* Either factory sport package Bilsteins, Koni's or high performance aftermarket dampers
* At least 550# front springs
* At least 1" front sway bar
* EHP (<=200UTQG) or R compound tires, not hard compound street tires
* You are comfortable with potentially less high speed directional stability than the Mazda factory alignment settings may provide
There are several ways to measure ride height. The most common are fender height & pinch weld height. If you are always using the same tire diameter, I recommend using pinch weld height as it's easier to get more precise and repeatable measurements. We always use pinch weld height method of measurement at our shop.
Measuring pinch weld height
Requires that you always measure with the same size tires. Take measurement from forward most and rearmost straight area of lower unit body pinch weld at it's lowermost edge. If you measure frequently, a small dot of contrasting paint or other mark on your measuring point is a good idea. Pinch weld heights listed below are assuming a 22. 7 to 22.9" tall tire which when loaded, will have a static loaded radius of about 11.25". Verify tire pressures before measuring ride height.
Measuring fender height
This measurement allows comparison between two cars with different tires. The actual fender shape and location can vary on a 10-20 year old car so this method is less precise. You must locate the exact center of the hub and this is difficult to do accurately. If you hold the measuring tape next to the hub you induces an error because the tape will not be 90° the ground plane. The fender lip on an unrolled fender can be 3/16" thick so two different people will often interpret the exact point differently. For these reason we recommend you not use this method and instead learn to use pinch weld heights for any future suspension tuning.
Other important stuff
These settings work best with the factory Torsen or OS Giken differentials. Ideally you will change the front to rear spring rate and anti-roll bar differential (FRC) biased towards the front. The OE FRC is only slightly front biased but the lower front camber serves to keep the car more or less neutral. I have found that setting the front camber from -.2° to -.5 ° more than the rear provide best grip and lowest lap times. Doing this on an otherwise stone stock Miata will result in an excessively loose, tail happy car so don't !
Make sure your car is basically healthy before trying to tune for more grip. This means carefully inspecting the entire suspension for worn, cracked, broken or mismatched parts. We often see high mileage Miatas with broken OEM end links, rubber bushings pushed out of control arms, bent suspension pivot bolts causing binding, bent wheels, mismatched tires, etc.
To maximize the performance you need to test, test, test. That means, same tires, same driver, same conditions, change one thing at a time. Record tire temps with a probe type pyrometer (no lasers!), lap times, tire wear patterns, tire pressures and most importantly, driver impressions immediately after run. There is no "best" alignment for every condition, only the"best" compromise that suits your needs. The more you are trying to squeeze out of the car on given course or track on that day, the more you have to test, record adjust, repeat. What works that day with the sun out, might be less than optimum 30 minutes later with the sun behind the clouds. You shouldn't expect to be able copy these settings verbatim and have it turn out 100% perfect for every possible car, driver, course. That's why race teams have highly skilled full time engineers constantly tweaking the cars to milk more speed out of the car for the conditions at that instant. Two different drivers under the exact same conditions can generate very different tire temps and arrangement. The settings you use are your setup.
Most DOT R compound race tires will develop their peak steady state lateral (cornering) grip at camber, toe and pressure settings that won't necessarily show even tread temps or wear. Generally when temps are evenly tapered across the tread and peak temps are within 15° at every corner, you are pretty close. The pyrometer is your friend, learn to use it! http://949racing.com/using-a-tire-pyrometer-949-racing.aspx
I usually shoot for tire temps 15~20° hotter on the inside than the outside with an even gradient to the cooler outside shoulder. Don't assume anything when reading tire temps or any other measurement. Drive it hard, pay attention to the car and experiment. Clocks don't lie.
We can't predict how your tires will wear because there are too many variables. Tire wear must some times be sacrificed if you are looking for the fastest possible setup. In general, when the car is at it's fastest and you have a good balanced set up, the tire wear will be pretty even. Using the street alignment, some ultimate grip and response must be sacrificed to provide best tire wear in those driving conditions. The alignment that gives best tire wear on track might destroy the tires on a car that only see street use. Conversely, a great street alignment might give really bad tire wear and performance on track.
Supermiata Street Alignment
For most street driven Miatas, tire wear is the most important parameter. Excess toe in or out will usually cause more tire wear than somewhat aggressive camber will. The OEM alignment numbers with more rear camber than in front, are designed to induce a bit of understeer. Lawyers ultimately dictate the OEM alignment, not the clever engineeers that designed the suspension. The actual suspension geometry is designed to require greater front than rear camber. The SuperMiata Street Alignment will generally result in no increase in tire wear over OEM and possibly a reduction in tire wear if you occasionally load the tires to maximum cornering forces. In general, this Street alignment is conservative and intended for cars that never slide their tires and spend almost no time at maximum conrnering loads.
NOTE: This alignment will require a slightly larger front sway bar. NB factory, FM or Racing Beat 1" solid bars will work. The RB 1.125 bar is to much for normal street tires (>240 treadwear). The Street Alignment may cause a 100% stock Miata to oversteer, or be too "loose".
>=5.25" front pinch weld height
Front camber: -1.4°
Front total toe: 1/16"
Rear camber : -1°
Rear total toe: 1/8"
SuperMiata Dual Duty Alignment (cars that see regular street use and some track/autocross)
In general, the Dual Duty alignment is intended for cars that will occasionally reach the limits of traction and slide the tires but don't want to give up too much tire wear for daily driving.
>=12" front ride height (measured hub center to fender)
>=4.75" front pinch weld height
Front camber: -2° (or as close as you can get to it)
Front total toe: 0
Rear camber : -1.7°
Rear total toe: 0 for track use. + 1/8" for autocross
SuperMiata Race Alignment
The Race Alignment is intended to win national championships. YRMV
Best suited for high grip tires such as Hoosier DOT, Toyo RR, etc
3.75~ 4.5" front pinch weld height. Xida's tend to work best for competition use with front pinch weld height close to 4.2".
Front camber: -3.5° (or as close as you can get to it)
Caster: >+4.5° or max available once you reach camber targets
Front total toe: 0
Rear camber : -3.0°
Rear total toe: +1/16~1/8"
Variations and extra stuff
The Miata seems to work best with about .25" positive rake (rear higher) measured at the pinch welds without driver in car and about 1/4 tank. It seems the the roll center axis doesn't like to be too far out of sync with the roll centers. In general, you can lower the rake to increase rear grip and improve transitional stability up to the point that the rear suspension begins to bottom. Lower the front to increase front grip and turn in response, again, until it begins to bottom the suspension excessively. In general, once we have an alignment we like, the only tuning we do at the track is to raise and lower the rear to fine tune. Lower to add rear grip, raise to reduce it. Too low and the suspension will bottom so that's your limiter.
Sway bars (anti-roll bars)
Disconnecting the rear sway bar on a lowered Miata allows the inside wheel in a turn to droop further. Since the inside front with swaybar still attached will not droop, rake changes. This means the front stays low, the rear jacks up in a turn. The effect is slight but it changes the roll axis, camber gain and a few other things. For autocrosser, this compromise is usually worth it as it will greatly reduce wheel spin and reduce oversteer during low speed transitions. For track use however, this will usually result in terminal understeer that will have you pulling your hair out trying to get rid of. In short, if you can get your autocrosser to work with the rear bar, keep it hooked up. If your budget or autocross class restrictions don't allow you to get good balance with the rear bar connected, then you have to ditch it. For track use, save yourself the headache and leave it on.
In general, the Miata likes a much stiffer front sway bar than stock, on the order on 3-4x more rate. We usually end up with 1.125" x.188 wall hollow bar. This front bar choice assumes at least 7" wide wheels and either EHP (Extreme High Performance) or R compound tires. For autocrossers, usually the OEM 11 or 12mm rear bar or sometimes nothing. For track cars, we like a 14mm rear bar. We have yet to find a car that needs more than a 14mm rear bar.
Miatas over 180whp or so can add +1/8" total toe in at the rear to attenuate corner exit power oversteer. Autocrossers forced to run wheels much narrower than optimum for the tire width will usually benefit from 1/8 to as much as 1/4" front toe out (CAUTION, this front toe out rapidly wears your tires on the street).
We're finding on some tracks that we are faster with as much as -4° front camber. Record tire temps and test to see what works for you. If you can't get enough front camber with your NA, welcome to the club! ISC Racing offers a offset front upper Delrin bushings optimized for 7" SCCA ITA wheels but they reduce bump travel with 8" or wider wheels. The Super Pro offsets, while pretty and very well made, won't stay in place so skip those. The only front lower bushing that will work is a custom Delrin or Acetal offset that is pinned in place by a bolt or stud. Only the forward bushing should be used in conjunction with a normal (not offset) urethane or rubber bushing. Installing a delrin/Acetal in forward and aft postions of the front control arms will cause binding The lower the ride height, the more static front camber you will get. This is one of the reasons we like to run the front ends as low as possible. The NB front subframe has a slightly higher roll center and more camber gain. For this reason, it is the best solution to gain more front camber and help keep the roll center closer to the CG after lowering. If your class allows the NB front subframe, do it.
More caster can help mid to low speed turn in, makes steering heavier, may increase wheelspin in very low speed turns with a Torsen or open type differential. I have experimented with low and high caster and I'm drifting back to preferring high caster settings, primarily for steering feedback at high speeds.
Favorite performance alignment shop in SoCal: West End Alignment Darren Nishimura
18008 S. Vermont Ave Gardena, CA 90248
Darren and his crew can also set up coilovers, cornerweight and generally get everything dialed