The Upgrade Guide for NA Miata Sway Bars

The Upgrade Guide for NA Miata Sway Bars. Suspension and handling changes are the ideal mods for a 1.6L or 1.8L NA Miata. Power is expensive to produce, which is why we advocate investing in suspension and handling components such as coilovers and sway bars.

Sway bars, also known as anti-roll bars, aid in the prevention of body roll and lean while cornering. Less roll means tighter turning and more control through the twisties. Sway bars are one of the best handling mods for the NA Miata, aside from stronger coilovers. This tutorial will go through how sway bars function, the advantages of modified NA Miata sway bars, and some of our preferred manufacturers.

The Upgrade Guide for NA Miata Sway Bars

Sway Bars and How They Work

Sway bars connect the front and rear suspension’s left and right sides. When you turn a corner, the car’s body weight shifts to the right. This increases the force on the right tires while lifting the left tires off the ground. “Body roll” refers to the weight of the car shifting to the right side. Body roll produces a twisting force, also known as torsion.

Sway bars work to balance out weight distribution by counteracting weight shifts to one side. When the weight shifts, the anti-roll bar twists, transferring weight to the opposite side of the car and reducing body roll.

Aftermarket sway bars for the NA Miata are available in a variety of thicknesses and materials, each of which affects the stiffness of the suspension.

Miata Sway Bar Upgrade Fundamentals

There are a few things to consider when purchasing aftermarket sway bars for the NA Miata. Thickness, solid vs. hollow, and adaptability are the most crucial topics to cover. Finally, the ideal configuration for you will most likely be determined by your goals and whether your Miata is used for track days, street driving, autocross, etc. Endlinks will also be discussed briefly.

The thickness of the sway bar

The front sway bar on ordinary NA Miatas is 19mm and 20mm on R-package Miatas. With the exception of cars with the Torsen LSD, the rear is 12mm for ’90-’93 NA6 models and 11mm for ’94-’97 NA8 models. To strike a balance between comfort and handling, the factory roll bars are fairly tiny in size.

Sway bars for the Miata are available in sizes ranging from 22mm to 25mm in the front and 14mm to 16mm in the rear. Due to the thickness of the piping wall, tubular or hollow sway bars have significantly larger diameters. Finally, the thicker the bar, the stronger/stiffer it is, and thus the greater the impact on body roll.

A few general guidelines for the Miata:

  • More understeer with a thicker front sway bar.
  • More oversteer = thicker rear sway bar.

Most autocrossers use the factory rear bar because an enhanced bar creates too much oversteer. If you enjoy autocrossing, here is a great resource for Miata autocross sway bar sizing. Furthermore, many people believe that 16mm is too large for track day events because it causes the rear end to swing out too much. Finally, it is setup dependent, but 14mm and 15mm bars appear to be more track oriented, whereas the stock bar is more autocross oriented.

I installed a 16mm rear bar on my NA6, and we’ll see how it performs on the track. But, realistically, unless you’re an experienced and serious track fan, I doubt you’ll notice the extra 1 or 2mm.

Sway Bars: Solid vs. Tubular

There are normally two possibilities for sway bar material. A totally solid sway bar is available, as is a tubular one with a hollow interior. Strength and stiffness are the two most significant distinctions between the two. Solid sway bars are heavier than standard sway bars, which are also solid. According to the Racing Beat solid bars, the rear is 1.3lbs heavier and the front is 4lbs more than standard. I can’t find weight data for other brands, but I’m guessing it’s similar.

In contrast, tubular bars are 1) stiffer than solid bars and 2) substantially lighter. According to Racing Beat, the tubular front bars are around 1.3x as robust as the solid bars. Furthermore, they weigh about 5.5 pounds, compared to 6 pounds for stock and 10 pounds for solid.

Only the front sway bar is available with tubular bars. A tubular rear bar would most certainly be overly powerful and stiff, resulting in excessive oversteer. Many track Miata drivers recommend going as stiff as possible in the front, making tubular a popular option.


Most, but not all, NA Miata sway bars are adjustable to varying degrees. Front bars often have three degrees of adjustment, while rear bars typically have two. At the most basic level, the various adjustment options influence the stiffness of each bar. It is usually common to maintain the front at the intermediate setting and the rear at the lower level for daily driving. Tubular bars are usually not adjustable.

We recommend sway bars that can be adjusted. It’s excellent to have a few alternative settings to play with when it comes to dialing in your suspension configuration.


Sway bars are connected to the suspension via endlinks. The standard endlinks are thin and weak, especially if they are over 30 years old. I recently upgraded the sway bars on my NA Miata, and the endlinks were the 30 year old stock ones, which were rotten.

Unfortunately, end links add approximately $150 to the expense of changing the sway bars, but they are required. When you add the added strength and stiffness from the improved bars, the stock endlinks, unless they are brand new, will burst very rapidly.

Sway Bars for NA Miatas

Keep in mind that fitment varies between NA6 and NA8 models. Sizing varies by brand and model for some of the brands, as well, as I’ll explain below. Again, the ideal option is very dependant on configuration and personal preference. Some drivers are fine with greater oversteer on the track, while others are not.

This is also affected by your coilover or spring/strut setup. If you are constructing a competitive track or auto-x Miata, your best bet is to speak with hardcore event drivers on ideal configurations. I do have a ’92 Miata NA6 and run the FM bars with MeisterR Club Spec coilovers, but I don’t track or auto-x enough to give you an informed perspective.

  • Eibach
  • The Flying Miata
  • Beat in Racing
  • Rear 5x Racing 14mm

1) Eibach NA Miata Sway Bars

Eibach sway bars are at the top of my list for one reason: they are the Spec Miata sway bars. Both the NA6 and NA8 models have 24mm front and 15mm rear bars. It’s a solid bar, so it won’t be as stiff as a tubular option, but the rear is a lovely 15mm, which should be adequate for track use. Spec Miatas have spring rates of 700/325, which is quite stiff, therefore these bars should complement a more street-oriented suspension configuration as well as track cars.

Eibach’s anti-roll bars include three degrees of adjustment in the front and two levels in the back. I appreciate that Spec suspension isn’t the most refined setup for track cars with no special criteria, but these are the spec bars for a reason and are fairly similar in size and pricing to our other options.

Sway bars are $375 and endlinks are $150-$200.

2) NA Flyin’ Miata Sway Bars

FM’s sway bars measure around 22mm in front and 16mm in back for the NA6, and 25mm in front and 16mm in back for the NA8. The FM sway bars, especially for the NA6, are more street-oriented. They’re a little less stiff in the front for comfort, and a little stiffer in the back for track events. They are suitably firm all throughout on the NA8.

These are my go-to sway bars for daily use. For starters, they are the most affordable. I got mine for $299, so they may have gone up a little in price, but they’re still a nice value play with the endlinks at $120 for all four, totaling roughly $500. Second, they are less aggressive in terms of stiffness, which makes them more comfortable on the road.

Overall, this is a good street setup. The rear suspension may be too firm for serious track cars, and the front suspension may be too soft on the NA6. Overall, a good value for money in terms of performance and comfort.

The Upgrade Guide for NA Miata Sway Bars

$369 plus $119 for endlinks

3) Anti-Roll Bars for NA Miata Racing

Racing Beat is the place to go for tubular front sway bars for your NA Miata. Racing Beat also provides robust sway bars all around. Fronts are 24mm and rears are 16mm across the board for solid bars. Also, the rear suspension is slightly stiffer than the Eibach option. Tubular bars are 1.125′′ in the front and have a 1.3x improvement in strength over solid bars.

Racing Beat provides a tubular front bar as well as a “race” tubular bar. The race tubular bar has a.188′′ metal thickness as opposed to.125′′ on the ordinary tubular, which increases its strength and rigidity. Tubular variants cost approximately $50 extra.

If you like to “go as big as you can” on the front bar, the Racing Beat Race Tubular is for you. A bracing kit for the front sway bar, which makes it even stiffer, is another unique product they provide. Overall, a terrific brand with great products, however it ranks third on my list because they are regularly sold out or on backorder.

Price: $350 for tubular or $315 for solid, plus $170 for endlinks.

4) 5x 14mm Racing Rear Bar

5x Racing sells a 14mm rear sway bar for $150 plus $99 for the endlinks to anyone concerned about oversteer on the track. The 14mm lens is more suited for street and autocross use. It’s a sturdy bar with 3-way adjustment, making it an excellent choice for anyone searching for a more inconspicuous rear bar.

$150 plus $99 for endlinks

Related : The Upgrade Guide for the Lexus IS300 Turbo Kit

Sway Bar Summary for NA Miata

After coilovers, sway bars are my second favorite NA Miata alteration. Sway bars improve handling and cornering by reducing body roll. When it comes to sway bars, thickness and design are important factors to consider. Many people believe in going as thick as possible in the front. The rear is more application-specific, with 16mm alternatives being a little too stiff for autocross and track events. For optimal stiffness, tubular front bars are ideal.

Overall, the optimum sway bar is determined by your objectives and driving style. On the streets, I run the FM NA6 bars with some really stiff coilovers and my NA corners like a boss. However, because I am not a track or autocross expert, I am not as picky. Overall, sway bars will improve handling and cornering performance on a basic Miata. Consult your local gurus for track enthusiasts.