X-Line PB42EX Big Brake Kits

Our PB42EX big brake kits include:

  • 2 x Compact, lightweight PB42EX billet 4-piston race calipers featuring stainless steel pistons and hardware (hard anodized).
  • 2 x 2-Piece floating disc assemblies featuring our SASS-float system, staggered cooling vanes and billet hats (hard anodized).
  • 2 x Billet aluminum caliper mounting brackets (hard anodized).
  • 2 x Stainless steel braided Teflon brake lines with 32-strand stainless steel braid and stainless steel end fittings.
  • All necessary mounting hardware.
  • Comprehensive installation and bed-in instructions.

Our X-Line PB42EX big brake kits are 'professional-grade' motorsport kits that have earned an excellent reputation on pro race cars both in our domestic and export markets. The kits are identical to those that we supply to numerous race customers and yet internal wiper seals and all stainless steel hardware result in them being perfectly useable for street and track day use as well (when used with suitable brake pad compounds). The compact, lighweight PB42EX 4-piston caliper is designed around a commonly available 18mm thick pad profile (FMSI: D592) that offers plenty of pad volume (and therefore pad wear life) when used on light - medium weight cars. Our PB42EX calliper accepts disc diameters ranging from 260-330mm in diameter and is available in a range of different caliper widths to suite disc thicknesses ranging from 24-32mm. This caliper design is ideally suited for use on lightweight rear wheel drive sports cars such as Mazda MX-5, Scion FRS / Subaru BRZ, Honda S2000 as well as on compact performance hatches such at the MINI Cooper S and Ford Fiesta ST. Typical PB42EX big brake kits for these cars would include 325x28mm or 325x30mm 2-piece disc assemblies. Powerbrake also manufacture a range of PB42EX big brake kits that include larger 330x32mm 2-piece disc assemblies for owners of medium size hatches such as the Ford Focus ST and Golf GTi that are looking for a compact big brake kit.

The features found in our PB42EX big brake kits perfectly reflect our X-Line design philosophy of:



The PB42EX calliper packs a lot of performance into a compact, lightweight package. As with all Powerbrake X-Line calipers, the PB42EX underwent extensive FEA analysis during its design. The caliper is machined from the highest quality aerospace grade aluminum billet using state of the art 5-axis CNC machinery. Strengthening ribs are employed in key areas to increase ridgidity. A series of channels are employed in key areas around the caliper piston bores to increase surface area resulting in more efficient cooling of the caliper and brake fluid. The calipers feature a type-3 mil-spec hard anodized finish for maximum wear resistance. The finish is impervious to heat damage even at extreme track temperatures. Calipers logo's and serial numbers are laser engraved resulting in marking that will never be damaged by brake fluid, solvents or heat. All calipers feature Powerbrake's Max Temp Recording (MTR) system that provides a permanent record of the maximum operating temperature reach by the caliper.

Our PB42EX calipers are fitted with ultra-high temperature pressure seals (manufactured from a proprietary polymer) that have been tested to caliper temps in excess of 480 deg F without failure. The calipers also feature high-temp internal wiper seals that protect the critical pressure seals from abrasion / damage and extend caliper service intervals. The internal wiper seal design allows for long term street use, while not being susceptible to melting under track conditions as is the case with the external rubber boots used by many of our competitors. As with all of our calipers, piston retraction is minimized, resulting in the shortest possible pedal travel under braking. Caliper crossover tubes are vibration damped and manufactured from seemless CuNi tubing to eliminate any chance of vibration induced cracking. Internal fluid passages are carefully designed to ensure effortless bleeding.

Extensive use of stainless steel components in all Powerbrake X-Line calipers mean that few, if any, competitive products will offer similar levels of corrosion resistance. All bleed screws, tube nuts, pad abutment plates, pad retention pins, anti-vibration springs and pistons in our X-line calipers are manufactured from stainless steel. Our hardware costs a lot more to manufacture than the plated mild steel hardware that most of our competitors use but follows our design philosophy of: Exceptional Performance - Extreme Durability. The only hardware components used in our X-Line calipers that are not manufactured from stainless steel are the high-tensile caliper cross bolts. These bolts are coated with a proprietary black coating that provides unmatched corrosion resistance (up to 1000 hours salt spray ISO 9227), chemical resistance and exceptional durability, while not negatively affecting bolt strength or service life at all. Again this level of investment on our part shows our dedication to building the most durable brake components on the market.

All Powerbrake X-Line calipers feature heavy-duty stainless steel pistons as standard. The pistons are scalloped to allow super-heated air to escape from the piston cavity. The outside surfaces of the pistons (which come into contact with the caliper seals) are then polished to a mirror finish. This significantly extends seal life. While significantly more expensive to manufacture than the aluminum pistons used by many of our competitors, stainless steel pistons conduct heat far slower than aluminum pistons. The result of this lower thermal conductivity is extended seal life and significantly reduced chance of vapor lock caused by boiling brake fluid .


The 2-piece, floating disc assemblies included in our PB42EX big brake kits include rotor friction rings cast from a proprietary High Carbon cast iron with high level alloying elements that increase rotor durability under high temperature use. The friction rings are attached to lightweight billet aluminum hats that are hard anodized for maximum durability and laser engraved with Powerbake logo's and serial numbers for full traceability. The disc drive hardware includes twelve high-tensile drive bobbins and our proprietary SASS-float system. The SASS-float system (originally developed for works Dakar Rally teams) allows for all the benefits of a full-floating disc assembly, while practically eliminating any chance of caliper piston knock-back (often experienced under track day or race conditions). Another positive spin-off is that this system also ensures perfectly quiet operation when our X-Line big brake kits are used in street applications.

Our SASS-float 2-piece disc assemblies allow for both radial expansion and contraction (experienced during disc heating and cooling cycles) as well as 0.35mm of axial float as preferred in track / race applications. Our SASS-float system is another example of how our X-Line big brake kits deliver championship winning race technology that can also be used by street and track day enthusiasts with no negatives. The fact that our full floating disc assemblies allow the disc friction rings to expand and contract independently from the lightweight aluminum disc hats, substantially reduces stresses within the disc that would otherwise be caused by disc expansion at high operating temperatures. The design results in improved pedal consistency as well as reduced disc distortion and cracking.

The disc friction rings feature our staggered cooling vane design, which results in improved cooling vane surface area allowing the rotors to cool more efficiently. The discs undergo multiple stress-relieving processes during manufacture resulting in an extremely stable finished product that will outlast many competitive discs on the market. It takes 12 weeks to manufacture a batch of our discs from casting to finished product. All Powerbrake X-Line discs are chemically de-greased and coated with a proprietary dry coating that ensures quick bed-in and maximum friction levels. All Powerbrake discs feature our MTR (Max Temperature Recording) tabs for accurate recording of max disc temps (4 - levels).

Every single Powerbrake disc assembly is measured in all key dimensions using measuring equipment capable of measuring accurately to tolerances of 10 micron. When it comes to QC, there is no batch or statistical quality checking of Powerbrake discs. Every single disc is measured. Our machining tolerances are up to three times tighter than the industry norm.

Caliper mounting brackets:

The caliper mounting brackets supplied in Powerbrake X-Line big brake kits are machined from aerospace grade billet aluminum. The resulting brackets offer an excellent balance between very high strength and ultra light weight. Our caliper mounting brackets are all type-3, mil-spec hard anodized. Each bracket is laser engraved with the Powerbrake logo, serial numers and other key information for easy identification and traceability.

Brake balance:

As with all our X-Line big brake kits, each PB42EX kit is tailored to the target vehicle in question. This involves careful software modelling of correct brake balance, brake torque outputs and pedal feel using proprietary brake simulation software developed in-house by Powerbrake. The result is that the caliper piston diameters in each kit are specified to match the target vehicle in question. Brake balance is optimized to best suite each vehicle platform and will perfectly integrate with ABS, EBD and other vehicle stability control systems. When driving a car fitted with a Powerbrake X-Line big brake kit, you will feel this attention to detail coming through by the way that the vehicle chassis reacts under braking. Powerbrake engineers have developed our brake simulation software over many years. This software is a key element in the success of our X-Line big brake kits.