The NB rear top hat is a critical suspension component for Mazda Miata NB models. Often overlooked, this unassuming part plays a pivotal role in optimizing ride quality, handling, and shock absorber performance. In this guide, we’ll dissect everything you need to know about the NB rear top hats, from its engineering to installation, compatibility, and aftermarket upgrades.
Table of Contents
Chapter 1: What Is an NB Rear Top Hats?
1.1 Anatomy of the NB Rear Top Hats
The NB rear top hats are a mounting interface that connects the rear shock absorber to the chassis. It’s designed to:
- Absorb road vibrations.
- Maintain proper shock alignment.
- Distribute load evenly across the suspension.
Material Composition: Most OEM NB rears top hats use rubber bushings, while aftermarket versions (like those from Diftech) employ polyurethane or spherical bearings for enhanced rigidity.
1.2 Why the NB Rear Top Hats Matters
A worn or damaged NB rears top hats can lead to:
- Premature shock failure.
- Uneven tire wear.
- Reduced cornering stability.
Chapter 2: OEM vs. Aftermarket NB Rear Top Hats
2.1 Limitations of OEM Top Hats
Factory NB rears top hats prioritize comfort over performance. Their rubber bushings degrade over time, leading to:
- “Sagging” suspension.
- Reduced responsiveness during aggressive driving.
2.2 Benefits of Upgraded NB Rear Top Hats
Aftermarket options (e.g., coilover-compatible top hats) offer:
- Adjustable ride height.
- Improved weight distribution.
- Compatibility with performance coilovers.
Case Study: Diftech’s 1.5-inch tall NB rears top hats allows Miata owners to achieve lower ride heights without sacrificing suspension travel.
Chapter 3: Compatibility of NB Rear Top Hats
3.1 Fitment for Mazda Miata NA/NB Models
The NB rears top hats is compatible with:
- 1990–2005 Mazda Miata NA/NB.
- Aftermarket rear shock assemblies (e.g., Fox, Öhlins).
Pro Tip: Always verify the top hat’s inner diameter (typically 12mm or 14mm) to match your shock shaft.
Chapter 4: Step-by-Step Installation Guide
4.1 Tools Required
- Jack stands.
- Torque wrench.
- Spring compressors.
4.2 Removing the Old NB Rears Top Hats
- Disconnect the rear sway bar.
- Unbolt the shock assembly.
- Use a spring compressor to safely dismantle the coilover.
4.3 Installing the New NB Rears Top Hats
Aftermarket NB rear top hats often require:
- Greasing spherical bearings.
- Torquing bolts to 35–40 ft-lbs.
Safety Note: Never skip using spring compressors—coilover springs store dangerous levels of energy.
Chapter 5: Performance Gains and Real-World Testing
5.1 Track Testing Results
A 2023 study by Miata Performance Magazine found that upgrading the NB rears top hats reduced lap times by 1.2 seconds on average due to:
- Sharper turn-in response.
- Reduced body roll.
5.2 Daily Driving Benefits
- Smoother ride over potholes.
- Reduced NVH (noise, vibration, harshness).
Chapter 6: Common Issues and Troubleshooting
6.1 Diagnosing a Failing NB Rears Top Hats
Symptoms include:
- Knocking noises from the rear.
- Visible cracks in rubber bushings.
6.2 Maintenance Tips
- Inspect every 30,000 miles.
- Lubricate spherical bearings annually.
Chapter 7: Expert Recommendations
7.1 Top 5 Aftermarket NB Rears Top Hats
- Diftech 1.5-inch Tall Top Hat (Best for Coilovers).
- Flyin’ Miata Bushing Kit (OEM+ Upgrade).
7.2 When to Pair with Coilovers
For track-focused builds, combine the NB rears top hats with adjustable dampers to fine-tune compression/rebound.
Chapter 8: FAQs About NB Rears Top Hats
8.1 Can I Use NA Top Hats on an NB?
Yes, but NB-specific top hats offer better geometry for lowered vehicles.
8.2 How Long Do NB Rear Top Hats Last?
Rubber OEM: 50,000–70,000 miles.
Aftermarket polyurethane: 100,000+ miles.
Conclusion
Upgrading your NB rear top hats is one of the most cost-effective ways to transform your Miata’s handling. Whether you’re chasing lap times or daily-driver comfort, this component deserves your attention.
