2025 Brake System Upgrade: Enhancing Modulation at the Limit

For the 2025 season, the objective wasn’t to fix a problem with braking performance, it was to enhance control at the threshold. The existing OE pedal setup was functional, but under threshold conditions, there was room to improve bias, pedal feel and system pressure at the front.

The main upgrade was a change to a balance bar master cylinder assembly.  Initially, we considered implementing a full Tilton pedal assembly (underfloor or under-dash).  However, there was not time before the first test to reengineer the cockpit layout with the bracing and structure required.

A fellow racer pointed me toward the Wilwood Tandem Master Cylinder with Integrated Balance Bar.  This compact unit retained the OE pedal assembly and simplifies service access.  Other options like OBP and Rix Engineering offered competitive systems, but the Wilwood’s accessibility and packaging were ultimately the deciding factors. Some servo-delete kits, particularly OBP’s, made access for adjustment and maintenance more difficult once installed.

To mount the Wilwood assembly, a small steel adapter plate was fabricated that bolts to the firewall. The Wilwood’s bolt pattern is slightly narrower than the OEM servo bracket, so the factory holes required minor elongation. Once installed, with the unit clamped to the firewall adapter and the OEM pedal support on the cabin side, the structure was surprisingly rigid.

Expecting significant firewall deflection (as reported by others), a heim-jointed brace anchored at ~45 degrees to a reinforced point on the firewall was fabricated. Post-installation testing revealed minimal movement on the engine side. I attribute this fore/aft rigidity to retaining the OEM pedal box structure. Some who reported excessive firewall flex had removed this reinforcement during conversion. Keeping the original steel pedal support in place appears to eliminate the need for additional bracing, longitudinally.

What will need to be addressed is the lateral movement of the pedal assembly on the cockpit side.  With the added force required to operate the manual brake system, it is now apparent that any lateral force on the brake pedal, such as during heal / toe operations does reveal some unwanted movement.