In early November, HFM conducted the first shakedown test of HFM.Parts’ new MX-5 Wilwood Big Brake Kit on a 1999 NB8A MX-5. Designed for both track use and daily driving, this kit features 280mm, 2-piece slotted rotors with pillar-style veins and T6-6061 aluminium top hats, aiming to enhance thermal management while reducing unsprung and rotating mass.
The shakedown provided an opportunity not only to validate the kit’s performance but also to gather comparative thermal data. Using an infrared thermal camera to record rotor temperatures immediately after each session, data was collected from two similarly modified NB8A MX-5s. One car was equipped with the HFM.Parts kit, while the other used single-piece, stock-size slotted aftermarket rotors. This setup allowed for a direct analysis of the thermal behaviour of both systems under comparable conditions.
Front Left: HFM.Parts MXWIL280
Average Lap Times: 1.49
Front Right: HFM.Parts MXWIL280
Average Lap Times: 1.49
Front Left: Slotted Aftermarket Stock Rotors
Average Lap Times: 1.59
Front Right: Slotted Aftermarket Stock Rotors
Average Lap Times: 1.59
This graph summarises the average temperatures recorded for the two brake rotor designs during a loosely controlled track session. The results highlight a significant difference in thermal performance: the HFM.Parts MXWIL280 rotors recorded an average temperature 67.5°C lower than slotted aftermarket rotors with a stock 254mm diameter. This represents a 34.2% improvement in heat management, indicating the HFM.Parts kit offers significantly enhanced thermal dissipation.
However, these results should be viewed as indicative rather than definitive. The conditions during the test session were loosely controlled, and multiple factors influenced the outcomes. While the temperature differences are notable, they provide only a preliminary insight into the potential performance benefits of the HFM.Parts kit compared to stock or alternative aftermarket options.
Interestingly, the test revealed a 10-second per lap delta between the two cars, yet the temperature difference consistently averaged 67°C. This suggests that the HFM.Parts setup delivered higher braking forces throughout the session, enabling more effective deceleration. Given the increased braking forces, the actual temperature difference between the two setups may be even greater than observed.
Addressing the Variables – Preparation for the Next Stage of Testing
The next stage of testing will look into eliminating as many variables as possible, including brake pad compounds, dimensions, brake fluids and the driver. While this approach does not eliminate all potential variations, it provides a realistic dataset that reflects the intended use case for the HFM.Parts kit.
Other Areas to Study
The 280mm rotor used in the NA and NB MX-5 Big Brake kits is designed as an OEM replacement for the ND MX-5. Future studies could examine the thermal performance differences over extended track sessions between OEM and HFM.Parts rotors.
This could involve two methodologies:
- Equipping one side of the car with OEM rotors and the other side with HFM.Parts rotors, assuming equal loading conditions.
- Running separate sessions with each rotor type and comparing their thermal behaviour during and after the sessions.
These studies could investigate whether the HFM.Parts rotors, with their pillar-style venting system and two-piece design, offer significant performance advantages.
Conclusion
We remain cautious about drawing firm conclusions from this initial testing. The conditions were not optimised for a rigorous comparison, and many variables that influence rotor performance were not fully controlled.
These preliminary observations reveal gaps in our research and underscore the need for further investigation. The shakedown phase was not designed to focus on this comparison, but it has provided valuable insights that warrant more detailed testing under a broader range of conditions.