Radium Master Cylinder Brace | 15-21 Subaru WRX/STI & 14-18 FXT (20-0255)

Some of your brake pedal travel never reaches the calipers; it disappears into a flexing firewall.

Stand on the brakes in a 2015+ WRX and the master cylinder pushes back against sheet metal that gives, softening the pedal exactly when you want precision. The Radium Engineering Master Cylinder Brace counters that flex with a 6061 billet aluminum brace that mounts to pre-existing threaded holes in the engine bay, no drilling, no permanent modification. Because the master cylinder flexes in an arc rather than straight back, a specially designed CNC machined foot contacts the cylinder to counteract that arc movement. Firmer, more consistent pedal in under 30 minutes.

What You'll Feel

• A firmer, more positive brake pedal with less dead travel before real bite
• Consistent pedal feel deep into a track session, when you lean on the brakes hardest
• More precise threshold braking and easier heel-toe work from a predictable pedal
• A quick, reversible install that leaves the car exactly as Subaru built it underneath

Features

• CNC machined 6061 billet aluminum construction, anodized and laser engraved
• Purpose-shaped machined foot contacts the master cylinder to counteract its arcuate flex path
• Preload adjusts via the anodized aluminum green bolt, locked with a stainless steel jam nut
• Mounts to pre-existing threaded holes; no drilling or permanent vehicle modification
• Installation takes less than 30 minutes with basic hand tools
• Also provides the mounting location for the Radium Air/Oil Separator Kit 20-0258 (sold separately)

The Details

Firewall flex is a geometry problem. When you brake hard, hydraulic reaction force pushes the master cylinder away from the pedal, and because the cylinder hangs off the booster, it does not move straight back; it swings through a slight arc. A flat brace face would contact it poorly through that motion, which is why Radium machined the contact foot to meet the cylinder correctly as it tries to move. Setting it up is simple: bolt the brace to the existing threaded bosses, run the green preload bolt in until the foot just contacts the master cylinder, and lock the jam nut. The result is that pedal effort translates into line pressure instead of sheet metal deflection. Fitment is left hand drive only, and if you are planning Radium's WRX air/oil separator kit, this brace is the mounting point it is designed around, which makes the pair a natural install day combo.

Kit Includes

• 1x CNC machined billet master cylinder brace, anodized and laser engraved
• 1x Anodized aluminum preload bolt with stainless steel jam nut
• Mounting hardware for pre-existing threaded holes

Applications

• 2015-2021 Subaru WRX (left hand drive only)
• 2015-2021 Subaru WRX STI (left hand drive only)
• 2014-2018 Subaru Forester XT (left hand drive only)