StopTech 83.131.4700 355mm ST-40 Big Brake Kit BMW
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StopTech 83.131.4700 Big Brake Kits combine larger diameter rotors with improved heat absorption and cooling together with stiffer calipers with piston sizing precisely designed for optimum brake bias to give you the ultimate braking system for street or track. StopTech's forged aluminum calipers and lightweight rotor hats also minimize unsprung and rotational weight which improves suspension response and vehicle acceleration.
The key to designing a big brake kit is to increase heat capacity and reduce compliance while optimizing the front to rear brake torque ratio, also called brake bias. Regardless of rotor size, brake pedal ratio, brake pad compound, or number of pistons in the calipers, maximum deceleration is limited in every situation by the available tire traction. Brake upgrades which add too much front brake torque shift the brake bias too far forward and will reduce the car's ability to utilize the maximum traction of the tires at all four corners (even on ABS equipped cars), increasing stopping distances dramatically. In addition, improper piston sizing will make the brake pedal much more difficult to modulate, which limits a driver's control of brake input.
All components of a StopTech BBK are carefully engineered to save unsprung weight, reduce compliance, and increase airflow. StopTech ST-40 calipers weigh just 7.65 lb (3.47 kg) unloaded. StopTech's removable caliper bridge resists yaw (flex) and allows pads to be changed without caliper removal. The StopTech AeroRotor uses uniquely designed AeroVanes inside the disc to optimize airflow through the rotor. StopTech AeroHats have directional stand offs between the rotor and mounting bell (hat) that increase airflow to the outside faces of the rotor by 50-100% over traditional 2-piece designs.
StopTech 83.131.4700 BBK Vehicle Fitment:
StopTech BBK Manufacturing: StopTech calipers are manufactured from fully forged aluminum. Piston diameters are carefully chosen to optimize brake bias on a per application basis and machined into the caliper. Finish machining, assembly, and test is performed in California.
StopTech AeroRotors are 100% made in the USA from a proprietary alloy chemistry which results in a friction ring with added crack resistance as well as improved functionality. A zinc coating can be added for corrosion protection on the unswept areas of the rotor.
StopTech AeroHats and caliper brackets are machined at StopTech in California from billet 7075 aluminum and hard-anodized to eliminate color change or fading. Inconel drive pin washers are used in the hat to rotor attachment, the washers are curved to add tension to the hat assembly, reducing rattle. Elongated drive pin slots allow separate expansion of rotor and hat to resist coning. The drive pins used to affix the hat to the rotor have a slightly out-of-round hole and are self-locking. They withstand high temperatures much better than typical lock washers and allow drive pins to move freely, yet securely, as hat and rotor expand at different rates.
StopTech stainless steel brake lines are made in California. StopTech brake lines consist of an expansion resistant Teflon inner line, which is then covered with a layer of stainless steel woven braid and coated with a clear abrasion resistant cover. The stainless steel braid provides support for the Teflon and is extremely durable against incidental impact and abrasion, the coating provides maximum protection against chaffing and particle intrusion. Every StopTech Stainless Steel Brake Line is tested to a pressure of 4,500 PSI.
StopTech sport brake pads use a a para-aramid compound and are copper and asbestos free to eliminate health and environmental concerns. StopTech ST-40 Big Brake Kits use FMSI D372 sized pads.
StopTech products are warranted to be free from defects in the materials and workmanship prior to installation. This warranty does not cover labor, misuse, faulty installation, failure of related parts or parts purchased other than from StopTech.
This product ships directly from StopTech in CA with a 1 week lead time