R-Line
Race Discs

Powerbrake 320x33mm R-Line off road race discs were specifically developed for FIA T1 Class 4x4 race cars, running 16” wheels. They are designed to be run in conjunction with our R-Line race calipers (standard or liquid-cooled versions). Every aspect of the disc has been specifically optimised for off road racing. The disc features 68 x directional cooling vanes, which is to the best of our knowledge the highest cooling-vane count currently available on the world market in a 320mm off road race disc.

Cooling vane design and air inlets were all designed to optimise disc cooling. The disc plate wall design delivers the optimum balance between air gap thickness (which influence disc cooling) and plate wall thickness (which influences the durability and service life of the disc). The discs feature 8mm thick mounting flanges with 12 x mounting slots that are designed to accept our disc drive bobbins / hardware in either semi-float or full-float configurations./p> {/sliders} {slider title="Can Powerbrake supply complete disc assemblies including disc hats and drive bobbins?"}

Yes, this a service that we offer to many of our off road race customers and vehicle builders. We are happy to quote on machining disc hats to customer drawings / specifications. In this case the disc hats are machined in our factory and mounted to our R-Line race discs (using disc drive hardware manufactured in-house by us). Complete disc assemblies are then delivered to the customer in either semi-float or full-float configurations. Of course spare disc friction rings and disc drive hardware can be supplied separately.

Powerbrake R-Line off road race discs are cast from a proprietary high-carbon cast iron alloy. The alloying elements in this specific material have been carefully selected to enhance disc service life and durability at high operating temperatures. The disc castings are all heat treated prior to final machining in order to deliver the most stable race disc possible.

The maximum radial pad track dimension is 48mm for our 320x33mm R-Line off road race discs. This is well suited to the race pad profile used in both our standard (R6IS) and liquid-cooled (R6ISW) R-Line off road race calipers.

Our 320x33mm R-Line race discs are cast from a proprietary high-carbon cast iron alloy that provides excellent durability and stability under the high thermal loads experienced under off road race conditions. The discs feature 68 x curved, directional cooling vanes. The design significantly increases cooling vane surface area and air-flow when compared to factory / OEM disc designs, resulting in vastly improved cooling.

The slot pattern chosen for our R-Line discs is our well-proven “RS” slot pattern that efficiently removes of sand, mud and water (commonly experienced under off road race conditions) as well as carbonised pad material from the disc / pad interface. The slot pattern also provides good bite and release characteristics.

Every single Powerbrake R-Line disc is measured for run-out and disc thickness variation (DTV) using Swiss measuring equipment. 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.

All our R-Line race discs are coated with a proprietary black surface coating. The discs are chemically de-greased before the application of this coating to ensure that no machining fluids or other contaminants that can be absorbed the brake pads and negatively affect brake performance are present on our discs at all. The coating is able to withstand extremely high temperatures and is flexible enough to expand and contract without flaking or peeling off of the disc surface during the constant thermal expansion and contraction cycles experienced by the brake disc. Our R-Line race discs require no cleaning or preparation using solvents prior to fitment at all. The discs are usable as they come out of the box. The black coating will be removed by the brake pads in the pad track areas within the first 4-5 brake applications.

All Powerbrake race discs feature our MTR system that provides a permanent record of the peak operating temperature reached by the discs. This information is extremely valuable when selecting correct race pad compounds for your application. The thermal-paint tabs are applied to the outside diameter of all R-Line discs (on both the inboard and outboard disc plates).

Each single-change paint colour (4-levels: Blue, Green, Orange and Pink) changes to white when a specific temperature is reached, hereby providing a record of the peak operating temperature of the disc. We also add a multi-change paint that can be used with a provided colour gradient chart to further refine the results to a more specific temperature.

Powerbrake also manufactures disc hats for many of our off road race customers and supplies complete disc assemblies to many off road race car builders. Our disc hats are machined from a solid billet of high grade aluminium alloy. Machining brake components from solid billet is expensive but it results in an extremely strong finished part. All hat designs undergo FEA strength and thermal analysis to confirm strength and rigidity under load. The hats are then finished with a dark grey, type-3 hard anodise for maximum durability and service life. Logos and other information are then laser etched on the outboard face of the hats.

At Powerbrake we have many years of R&D invested in disc float systems. For our R-Line off road race disc assemblies, we generally employ our full-float system that has been very well proven within our product range over many years.

The full-float system allows the disc friction ring to expand and contract radially without any restriction as it heats and cools. This significantly reduces stresses within both the disc friction ring and the disc hat and reduces the chance of disc distortion and cracking, while ensuring a very consistent brake pedal feel.

The full-float system also allows a small amount of axial (inboard / outboard) disc movement that allows the disc to perfectly centre itself as it moves through the caliper. Axial float can also minimise certain forms of piston knockback such as knockback caused by bearing flex.