The Nissan 370Z is a popular sports car known for its performance and agility. However, enthusiasts often seek to enhance its capabilities further through differential and suspension upgrades. These modifications can significantly improve power delivery and handling, making the driving experience even more exhilarating.

Understanding the Differential

The differential is a crucial component in any vehicle, allowing the wheels to rotate at different speeds during turns. In the Nissan 370Z, the stock viscous limited-slip differential is a compromise between daily drivability and performance, leaving room for improvement. Upgrading the differential can lead to better traction, improved acceleration, and enhanced cornering capabilities, especially when you push the car near its limits on track or spirited back roads.

Types of Differential Upgrades

  • Limited-Slip Differential (LSD): A mechanical LSD replaces the factory unit to distribute power more effectively between the rear wheels, reducing wheel spin and improving grip during hard acceleration and corner exit.
  • Helical LSD: Found in products from Quaife and OS Giken, helical differentials use worm gears to provide smooth, progressive lockup. They are ideal for street use because they offer predictable behavior without the chatter or maintenance of clutch-type units.
  • Clutch-Type LSD: Units from Nismo and Cusco use stacked clutch packs to create aggressive lockup. They excel in track environments where maximum traction is needed but can be harsher on the street, producing noise and requiring periodic rebuilds.
  • Torque-biasing (Torsen) LSD: The factory 370Z Nismo trim comes with a Torsen differential that provides good all-around performance. Upgraded Torsen units with higher bias ratios are available from Z1 Motorsports for drivers seeking more aggressive power delivery without full clutch-type behavior.

Differential Gearing and Final Drive Ratios

Beyond the LSD type, changing the final drive ratio (ring and pinion gears) can dramatically alter acceleration. A numerically higher gear ratio (e.g., 3.7:1 or 4.08:1) replaces the stock 3.36:1, making the engine rev faster and improving throttle response. This is especially effective for naturally aspirated builds. However, it reduces top speed per gear and increases highway RPM, so weigh your intended use carefully.

Installation and Cooling Considerations

Installing an upgraded differential requires dropping the rear subframe or removing the differential assembly. It’s a job best left to experienced mechanics unless you have a full shop setup. Additionally, if you plan to track the car heavily, consider adding a differential cooler (e.g., from Concept Z Performance) to prevent fluid overheating and premature wear. Use synthetic gear oil with the correct friction modifier for your LSD type to ensure quiet, reliable operation.

Suspension Upgrades for Enhanced Handling

The suspension system of the Nissan 370Z plays a vital role in how the car handles and rides. The double-wishbone front and multi-link rear setup is inherently capable, but stock bushings, dampers, and spring rates are tuned for road comfort. Upgrading the suspension can improve stability, reduce body roll, and enhance overall driving dynamics, making the car feel more planted and responsive.

Key Suspension Components to Upgrade

Coilovers

Adjustable coilover kits allow drivers to customize ride height, damping, and often preload, providing a balance between comfort and performance. Top choices for the 370Z include KW Variant 3 (excellent street/track balance), Ohlins R&T (high-quality remote reservoirs), and BC Racing BR series (budget-friendly with many adjustments). For aggressive track use, consider GReddy Type-S or Tein Flex Z. Coilovers also allow you to lower the car’s center of gravity, improving cornering limits.

Sway Bars

Upgrading to stiffer sway bars (anti-roll bars) reduces body roll during cornering, enhancing the car's responsiveness. A popular combination is fitting a 27mm adjustable front bar and a 22mm adjustable rear bar from Eibach, Hotchkis, or Whiteline. Adjustable links allow fine-tuning to address understeer or oversteer. Note that overly stiff rear sways can induce snap oversteer, so balance is key.

Strut Braces

Installing strut braces increases chassis rigidity, improving steering response and consistency. A carbon fiber or aluminum front strut bar (e.g., from Cusco, Carbing, or AEM) ties the front shock towers together. A rear strut brace or a C-pillar bar further stiffens the chassis, especially in convertibles. For maximum rigidity, consider a GK Tech bolt-in roll bar or full cage if you plan to compete.

Bushings and Control Arms

Replacing soft rubber bushings with polyurethane or spherical bearings eliminates slop in the suspension, providing more precise wheel control. Focus on the front lower control arm rear bushing (known to cause toe change under braking) and rear toe arms. Adjustable rear camber arms and toe links are essential after lowering the car to realign geometry and prevent premature tire wear. Brands like SPL Parts, GK Tech, and Moog offer durable components.

Alignment and Corner Balancing

No suspension upgrade is complete without a professional alignment and, ideally, corner balancing. For a street/track 370Z, aim for -2.5 to -3.0 degrees front camber, -2.0 to -2.5 degrees rear camber, with 0 to 1/16 inch toe out front and 1/16 to 1/8 inch toe in rear. This setup promotes turn-in crispness and high-speed stability. Corner balancing ensures all four wheels support equal weight diagonally, maximizing chassis grip.

Lowering Springs vs. Coilovers

If budget is tight, lowering springs (e.g., Eibach Pro-Kit or Swift Spec-R) can reduce ride height and lower the center of gravity while working with stock dampers. However, shock life and ride quality suffer. Coilovers offer full adjustability and better damping control, making them the superior long-term investment for serious handling.

Benefits of Upgrading Differential and Suspension

Upgrading the differential and suspension of the Nissan 370Z offers numerous benefits that can transform the driving experience. Here are some of the key advantages:

  • Improved Traction: Better power delivery through an upgraded differential ensures that more power reaches the ground, reducing wheel spin and wheel hop, especially during aggressive corner exits or on uneven surfaces.
  • Enhanced Cornering: A stiffer, better-damped suspension setup allows for sharper turns, higher cornering speeds, and increased confidence when navigating curves. Reduced body roll keeps tires in better contact with the road.
  • Increased Stability: Upgraded bushings and alignment settings lead to a more stable ride, especially at higher speeds, reducing the tendency of the rear end to step out under braking or mid-corner bumps.
  • Customizable Performance: With adjustable components, drivers can tailor their setup to match their driving style and preferences, whether for daily commuting, autocross, road course, or drag racing.
  • Weight Reduction: Some aftermarket suspension components (e.g., aluminum coilovers, lightweight sway bars) reduce unsprung mass, improving ride quality and tire responsiveness.
  • Predictable Behavior at the Limit: A mechanical LSD combined with properly tuned suspension gives the driver consistent, predictable breakaway characteristics, making the car easier to control during spirited driving or competition.

Practical Considerations and Maintenance

Before diving into upgrades, assess your driving goals and budget. A balanced approach—starting with tires, then alignment, then a mechanical LSD and coilovers—usually yields the greatest PPM (power-per-minute) improvement. Do not neglect supporting mods like upgraded differential bushings or subframe inserts, as they prevent the new components from moving under load. Consult a specialist shop that knows the 370Z platform, such as Z1 Motorsports or a local reputable alignment shop with corner weight scales.

Routine maintenance intervals should be shortened after upgrades. Check differential fluid every 15,000-20,000 miles (or after every track day) and replace with proper LSD oil. Inspect suspension ball joints, rod ends, and sway bar links for wear annually. If you run spherical bearings, they will require periodic cleaning and lubrication to prevent noise and binding.

Common Myths and Mistakes

  • Myth: "A differential upgrade is only for track cars." In reality, even a helical LSD improves daily driving in rain or on loose surfaces by reducing one-wheel spin.
  • Mistake: "Stiffer springs always mean better handling." Overly stiff springs can cause the car to bounce over bumps, reducing overall grip. Match spring rates to your tire grip and driving conditions.
  • Myth: "You don’t need an alignment after coilovers." Changing ride height drastically alters alignment angles. Skipping the alignment is dangerous and will eat tires quickly.
  • Mistake: "More negative camber is always better." While camber helps cornering, too much reduces braking and straight-line traction. Stay within the range recommended by experienced 370Z tuners.

Conclusion

For Nissan 370Z enthusiasts, upgrading the differential and suspension is a worthwhile investment that can yield significant improvements in power delivery and handling. By selecting the right components and making thoughtful modifications, drivers can elevate their driving experience and unlock the full potential of their vehicle. Whether you prioritize street manners or track domination, the aftermarket offers a wealth of proven parts to refine the 370Z into a sharper, more responsive machine. Always research reputable brands, consult with experienced builders, and invest in professional installation and tuning to get the most out of your upgrades.