Stoptech Rear Gas-Slotted Rotors - E82 135i (324X22mm)

Direct replacement REAR gas-slotted brake discs. These rotors feature a unique black electro-coating that is designed to prevent corrosion. Each rotor is e-coated then double-ground and balanced to ensure an even surface with no vibration. The e-coating is the best anti-corrosion protection currently available in replacement rotors. Most aftermarket rotors are not coated, allowing surface rust to form right away, which is unattractive when brakes can be seen through your wheels.

Slotting a rotor helps to release gases that build up between the rotor surface and an out-gassing brake pad. Without an escape, this thin layer of gas will cause a delay until the pad cuts through gas layer. The slots in our rotors allow the gases to escape giving better braking performance. For track and racing use, slotting is preferred over cross-drilling because the slots don't take away as much mass from the rotor and won't suffer from structural cracks.

Most Power Slot rotors match the original factory cooling vane design. In the most popular sports car and light truck applications, Power Slot has improved the design by using directional (left- and right-handed) vanes to improve cooling. This represents a distinct upgrade from the original equipment rotors, which usually feature a straight vane or pillar vane design. The directional vane is a more efficient air pump. The resulting increase in airflow translates into greater resistance to brake fade and faster recovery from temperature spikes generated by aggressive braking maneuvers.

Power Slot rotors feature a signature "short slot" design. The slot improves brake system performance by wiping away the debris of used friction material that otherwise accumulates between the rotor and pad. This keeps fresh pad material exposed to the rotor surface and helps prevent pad glazing. The edges sweeping the pad slightly increase the effective coefficient of friction, or "bite", amplifying brake system response to pedal input. By providing an escape path for water, slotted rotors can also improve initial brake response under wet conditions.

Power Slot rotors are also available with an optional cryogenic treatment called Power Slot Cryo. Although cryogenic treatment is invisible to the naked eye, many of Power Slot's fleet customers are sold on its ability to extend the wear life of the brake disc. Deep cryogenic treatment is a one-time process that permanently improves the performance and service life of metal components, from brake rotors and engine parts to machine tools and gear sets. Using a proprietary, computer-controlled process, the metal is cooled to -300?F before gradually being heated to +300?F, and then slowly returned to room temperature as the final step.

Every Power Slot rotor is finished with a black e-coating on both sides of the hat, inside the cooling vanes and on the outside edge. E-coating is a superior electro-statically applied finish designed to withstand 400 hours of salt water exposure without rusting. This is especially important on both mounting faces of the hat where it touches the hub flange and back face of the wheel. Any accumulation of rust in these areas can lead to installed lateral runout issues.

Power Slot rotors feature a double disc ground, taper free finish. Double disc grinding ensures parallelism, eliminates run out and provides near perfect disc thickness variation (DTV). Double disc grinding leaves a non-directional finish on the friction surface area for more effective pad and rotor break-in. This special finish also provides quieter and smoother stops.

Power Slot rotors feature 100 percent fully machined finishes including rotor hats. This extra process provides better rotor balance and creates a cleaner, more finished looking component.

Power Slot brake rotors are mill balanced to a tolerance of less than 2 oz-inch. This additional machining operation reduces feedback associated with rotor vibration and provides a smooth, confident application of braking force.

Center-split core castings provide proper heat transfer and thermal efficiency, resulting in superior braking power and safety.

Power Alloy metallurgy is another unique feature in many of Power Slot's rotors. Quality and performance live inside the rotor too. Choosing the correct foundry partner and working to improve the metallurgy are all part of Power Slot's continuous improvement process that helps to reach established targets for hardness and tensile strength. Many of Power Slot's top-selling part numbers are cast using this Power Alloy iron specification, an enhancement in the carbon and molybdenum content of the iron. Carbon and molybdenum promote crack resistance and improve noise, vibration and harshness (NVH).

This item fits the following BMWs:
2008-2013 E82 BMW 135i 135is