Large two-piece 12.7" diameter by 1.25" thick vented and slotted rotors with 4-piston forged aluminum Wilwood calipers greatly improve the rear brakes by increasing both stopping power and thermal capacity.
Note
- Fits 1999-04 Mustang Cobra IRS only. Will not fit solid axle.
- This kit does not include a parking brake. Installation of this kit will disable the stock parking brake, making it non-functional.
- The four-piston calipers require more clearance to the wheel spokes than the stock Cobra Varga rear caliper. Wheels that clear 4-piston front calipers from Brembo and StopTech will clear these Wilwood calipers.
- Brake pads are not included with this kit because they should be chosen to complement the front pad compound on your racecar.
- For other brake pad brands: This Wilwood caliper (120-9725) uses pad plate #7816, with an overall pad thickness of 0.60".
- Two versions of the kit are available. Both kits utilize a two-piece hat and rotor assembly. The MMBAK-15 kit includes fixed hat rotors, while the MMBAK-16 kit has floating hat rotors. Our exclusive mounting brackets easily attach the Wilwood calipers to the standard Cobra IRS spindle.
- Best used with high performance Motul brake fluid.
This kit includes:
- Two-piece, directional, 12.72" x 1.25" vented and slotted rotors for increased brake cooling and stopping power. Rotors are larger diameter and thicker than stock rotors, increasing thermal capacity. They have larger cooling vanes and asymmetric slots to improve cooling.
- Rotor hats are machined from aluminum for reduced weight. Hats are fixed-mount versions.
- Four-piston forged aluminum Wilwood calipers are lightweight; yet provide high brake torque for maximum stopping performance. Calipers utilize larger-than-stock pads (pads not included). The increase in friction material volume prolongs pad life.
- Stainless steel brake hoses are included, replacing the stock rubber hoses for improved pedal feel and increased reliability under the extreme stress of open track use.
Tech
- MM developed these IRS brake kits on our own American Iron racecar because we found the temperature of our standard Cobra rear rotors exceeded 1,200 degrees at the end of a track session. Once we installed this kit our rotor temperatures were reduced to less than 900 degrees, and the rigid four-piston caliper greatly improved brake pad life and pedal feel by eliminating taper wear of the pads.
- The lower center of gravity, longer wheelbase, better weight balance, and improved suspension of a racecar reduces forward weight transfer during braking, which gives the car the ability to utilize more rear brake bias than a street-oriented Mustang suspension can tolerate. Dialing in more rear brake with an adjustable proportioning valve will overwhelm the thermal capacity of the stock Cobra rear brakes. The larger rotors of the MM kit provide more thermal mass, allowing an increase in rear brake bias while keeping temperatures lower than with the stock Cobra rotors.
- The increase in thermal capacity provided by this MM kit allows increasing the rear brake bias. This allows a more proper match of the rear brake capacity to upgraded front brakes. A better balanced, better performing brake system not only shortens stopping distances, it inspires driver confidence, which leads to lower lap times.
- The MM IRS Racing Brake Kit should only be installed with properly matching front brakes. The appropriate minimum size front rotor is the standard Cobra 13" rotor. The thicker rotors of a StopTech front brake kit are much more desirable. The stock Cobra aluminum PBR sliding-bridge calipers are the minimum suitable front caliper choice. Fixed-mount four-piston front calipers provide a much more balanced match with the Wilwood calipers of this MM kit.
