Miata Handling Upgrades Explained

Introduction

Currently, the biggest handling upgrade on my Miata is a set of aftermarket wheels and tires. These have significantly increased grip and made a noticeable difference in the car’s performance. I want to continue chasing performance gains, so the next step will be modifying the suspension. Several upgrades can dramatically improve the Miata’s handling, including sway bars, coilovers, and adjustable suspension arms. Each of these affects handling in different ways. Below, I’ll explain how each component works, what effect it will have on my car, which one I’m purchasing, and why.

Sway Bar

When a car corners, centrifugal force pushes it outward from the turn center. This causes a phenomenon called body roll, where the car’s chassis leans or "rolls" to one side due to uneven suspension compression. For instance, in a left turn, the suspension on the right side compresses more than the left. This imbalance can raise the car’s center of gravity and reduce cornering stability, as shown below.(COG = Center of Gravity)






A sway bar connects the left and right sides of the suspension to counteract this effect. When one side compresses, the sway bar resists the difference by transferring some of the force to the other side, helping keep both sides more level. For example, without a sway bar, the left coilover might compress only 10% while the right compresses 40%. With a sway bar, both sides would compress more equally, reducing or eliminating body roll and improving stability, as shown below.



Aftermarket sway bars are stronger and stiffer than the factory-installed bar. I’ve chosen a tubular 1.125" racing sway bar from Racing Beat. It’s their mid-range option. It is lighter and 1.3x stronger than their solid bar, but not as extreme or heavy as their oversized 1.25” tubular bar. The oversized bar could deform my stock sway bar mounts and wouldn’t fully reach its potential in my current setup.

This bar offers two mounting holes for adjustment: one closer to the pivot axis and one farther away. Using the hole farther from the axis allows the suspension arms to exert more leverage, making the bar feel softer. Mounting closer to the axis reduces leverage, making the bar stiffer. I’ll start by using the closer holes for maximum stiffness.

Coilovers

Coilovers replace the factory shocks and offer far more adjustment than stock suspension. Higher end coilovers offer 5 main benefits. These include:


- Lower Center of Gravity: Coilovers allow you to adjust ride height, lowering the car’s center of gravity. This reduces body roll, increases cornering stability, and improves responsiveness.

- Optimized Suspension Travel: By dialing in preload, you can control how much suspension travel is available under normal driving conditions. A well tuned preload setting prevent bottoming out and improves compliance over bumps and track curbing.

- Damping Adjustments: Coilovers feature adjustable compression and rebound damping, allowing you to fine tune how quickly the suspension reacts to bumps (compression) and returns to its normal state (rebound). Proper damping ensures that your tires stay planted and predictable through corners.

- Endurance Coilovers are designed for race conditions and will perform better, for longer. Even under high heat or extended use cycles, coilovers will retain predicatble, tuned characteristics.

- Improved Weight: Many aftermarket coilovers use more advanced materias that are stronger and lighter than stock, allowing for a lighter-weight system.


Coilovers typically allow four main types of tuning to achieve these benefits. They include:


- Ride Height: Adjusts the overall length of the shock body to raise or lower the car, affecting both stance and center of gravity.

- Preload: Controls how much spring compression exists when the car is at rest. This affects how much suspension travel is available and how the suspension behaves under load.

- Compression Damping: Adjusts resistance when the shock compresses.

- Rebound Damping: Adjusts resistance as the shock returns to its original length.


I prefer to use the full shock stroke with enough preoload to maintain about 25% of suspension travel in a neutral state. This is a nice mix of avoiding bottom outs while offering smooth suspension

After narrowing it down to the Supermiata Xidas and Öhlins DFVs,(based on my budget and performance wishes) I decided on the Öhlins DFVs due to quicker availability and larger service network. They are well regarded for their balance between track performance and street comfort.


The coilovers are fairly easy to install. The car now handles noticeably better. Here you can see the Ohlins fresh out of the box, and installed. You might notice the installed red swaybar, which is the racing beat bar discussed above.

Adjustable Suspension Arms

Adjustable suspension arms allow for greater alignment tuning than the factory setup. The stock Miata chassis allows for approximately:

-0.5 to -2.0 degrees of front camber
-1.0 to -2.5 degrees of rear camber
Significant toe adjustment both from and rear

Aftermarket arms can extend these ranges, which is beneficial for aggressive track or drift setups where you want more negative camber for maximum grip during hard cornering. However, for most street and occasional track drivers, the stock adjustability is more than sufficient.

As such, I won’t be buying aftermarket arms for now as the factory setup offers enough flexibility for my current goals.

Lessons Learned

• Effect of body roll on vehicle driving
• How swaybars reduce body roll
• Coilover adjustment and applications
• Aftermarket suspension arm pros and cons