UUC's MINI Big Brake Upgrade

The MINI was an instant hit with the car-buying public. Great handling, great looks and loads of fun, all at a reasonable price. The Cooper S brought even more to the party; a real driver's machine. But as more owners began to seriously flog their cars on track days, a few shortcomings were noted. Chief among those were the brakes. While fine on the street and around a low-speed autocross, fade becomes an issue on the track. So UUC Motorwerks set out to offer a solution. Working with Stainless Steel Brake Corp., it has come up with an affordable solution to soft brake pedals for all you "track junkies."

UUC's kit consists of massive 12.25x1-in. internally vented, swirl-slotted cast-iron rotors, SSBC Force 10 Tri-Power calipers and direct bolt-on carriers, pads, DOT-approved stainless-steel brake lines and all necessary hardware. Originally designed as a direct replacement for C5 Corvettes, the two-piece, three-piston aluminum caliper won the GM 2003 SEMA award for "Best High-Performance Product." For UUC's MINI application, the stainless-steel pistons--with triple internal seals--have been redesigned to maintain proper balance with the MINI's stock rear brakes. A matching rear kit with the same swirl-slot pattern, SS brake lines and matching pads will be available soon.

"The idea is to get larger areas in all the important surfaces," said UUC's Rob Levinson. "The key to braking is converting mechanical energy--the car's speed--into heat energy and dissipating it as quickly as possible. SSBC's rotor's directional, curved vanes help with this. There is also the question of how much heat the components can absorb without overheating before they can transfer it to the surrounding air. And, simply adding bigger front brakes usually creates too much front bias. We adjusted for that by having SSBC build the Tri-Power calipers with smaller pistons. With our pad recommendations, the brake bias change is under 3% from the stock components. Our swirl-slotting is an excellent way to improve pad-to-rotor contact under a variety of situations. Things like water and even the off-gassing of a hot pad can affect the friction between the pad and rotor. The slots have a vent path, ensuring good contact is maintained in these situations. The shallow angle swirl-slotting is a design that keeps a slot under the pad at all times."

The kit is shipped with street-friendly and long-lasting Hawk pads in a fitment originally for GMC full-size truck rear brakes. They're available at any auto parts store. They also use a backing plate similar to the C5 Corvette front pad, a unit the Tri-Power caliper is designed to accept. This means you have a wide variety of pads from Ferodo, Performance Friction, Hawk, Pagid and others--in street to race compounds--available for the asking. Ask Levinson for advice.

Mechanically the swap is not difficult but, as always, if you have any doubts about your ability to do the job correctly, have a reputable shop do it instead. After supporting the car on jackstands, remove the wheels. Use a 7mm Allen to remove the two bolts holding the caliper to the carrier and set it aside. (Wait until the new parts are in place to disconnect the brake line.) Remove the two 16mm bolts holding the carrier to the hub and remove it. A T50 Torx screw holds the rotor to the hub, remove it and set the rotor aside. Use aviation snips to trim the heat shield (top and bottom) to make room for the new caliper. Be sure to dress the sharp edges with a file.

Set the new rotor on the hub and hold it in place with the T50 set screw (the prototype rotors in the photos do not have the appropriate hole, normal production will). Slide the new caliper and carrier assembly--with pads in place--over the rotor and use the supplied bolts and lock washers to install it using the factory holes in the spindle. Torque to 65- to 70 ft-lb. Use new copper crush washers (supplied) on either side of the banjo fitting and snug the new brake line down (it goes in the back side of the caliper), but don't fully tighten the bolt yet. With everything in place, put some rags down--get ready for a mess--and disconnect the old brake line, using the proper wrenches to avoid rounding anything off. Try to work quickly as ABS brakes can be difficult to bleed if air enters the pump. And be careful, brake fluid is an excellent paint remover! Put the new brake line in place and tighten the connection.

Grab the rotor and caliper and swing the strut through its turning range while watching the brake line. Adjust the angle of the banjo fitting if necessary, and tighten the bolt. Use a razor knife to slice the grommet on the old brake line; remove it; place it slice in on the new line and press into the bracket on the strut. Check the brake fluid level, and repeat on the other side. Power bleeders make the next step a one-person job or enlist a friend to pump and hold the pedal while you bleed any air out of the system. For normal bleeding the topmost bleed nipple is used to purge old fluid. However, each caliper has three bleed nipples to help get stubborn air bubbles out of the caliper after the initial installation. Work bottom to top and make sure the reservoir is always adequately filled during bleeding.

Your new brakes may feel a bit odd while you are carefully bedding them in. SSBC uses a proprietary three-step plating process to keep corrosion to a minimum, and the plating must wear off the swept surfaces before the brakes will perform at their best. Expect the process to go fairly quickly--the swept area will look pretty ugly for a short while--but don't be surprised if the pedal feel isn't what you expect initially.

Once properly bedded, though, the kit pays real dividends. UUC's Sunny Sabnani established a baseline for the stock system with 20 60-to-0-mph ABS-assisted stops in a row with a 2-min. break after 10 stops to measure rotor and caliper temperatures. After 10 stops, the distance jumped from 120 feet to 158 ft (average 135 ft) with smoking pads and a spongy pedal. The rotor temperature was past the Raytek MiniTemp MT Pyrometer's 525°F max and the caliper showed 275°F.

The short break helped, but the second 10 runs still averaged 141 ft with the rotor temp still off the scale and the caliper temperature climbing to 410°F. Pedal feel was described as 'wooden' and the fluid had been boiled, necessitating bleeding the system.

The UUC upgrade on the other hand, averaged 128 ft over the first 10 stops with rotor and caliper temps of 380°F and 220°F respectively and no change in pedal feel. The average stopping distance climbed slightly to 132 ft for the second set of 10 runs with the rotor temps climbing to 485°F and the caliper to 280°F but the pedal feel never changed. In fairness, it should be noted, Sabnani also installed matching rear pads. He also noted braking was more linear, stayed very consistent and the sometimes twitchy Cooper S was even more controllable than stock.

"I really like that they bolt right up," said Randy Webb of Webb Motorsports of "pulley party" fame. "And that you don't need spacers with most 17-in. wheels." (Some of the factory wheels will, though, UUC is checking fitments.) UUC hand-delivered the prototype kit to Webb just in time for a 3-day track event at notorious brake-eater Blackhawk Farms. "After pulling the foglights and jury-rigging some brake cooling ducts, the UUC kit performed flawlessly--and has for several other track days since. Stock MINI brakes would have only been good for one stop. The brakes work great, the only issue is the weight," said Webb. The kit's downside, according to UUC's UPS scale, is the 9 lb of unsprung weight added per side.

Remember also, UUC--the Underground Upgrade Club--understands. As its Web site states: "For your convenience, UUC Motorwerks accepts cash and we ship discretely! We can even ship to your employer!" Kind of wonder where they learned that.