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Project Street S MINI Part 1: Bigger is Sometimes Better

Pablo Mazlumian
May 5, 2003 SHARE
0306_01z+mini_cooper_s_sedan+front_right Photo 1/6   |   Project Street S MINI Part 1: Bigger is Sometimes Better

As soon as the new MINI was released to the United States, the tuners and accessorizers went into a frenzy. We knew what drove this headlong rush--there are plenty of good reasons we named the supercharged MINI Cooper S european car's 2002 Grand Prix winner (see european car, 08/02). The first time we drove the little sports hatch, we knew there was a lot more performance lurking within its outstanding chassis. So, caught up in the heat of the action, we just had to build a couple of MINI projects.

This one we've named Project Street S, and, as with Project Maxed-out MINI, it begins with the MINI Cooper S. At face value, the 163 bhp from its supercharged four banger won't boil anyone's blood--until you drive it. That extra 48 bhp over the base MINI is put to excellent use and, if you choose, can be seen, smelled and heard from screeching, burning rubber. Among today's heavy vehicles, the MINI is a featherweight at 2,700 lb and feels as nimble and precise through the corners as most sports cars.

0306ec_streetmini02_z Photo 2/6   |   Although a good performer, the stock system had to go in our headlong search for sportier street performance.

So, is it a sin to want more? Well, we do...and even though it might mean an extra prayer before bed tonight, we're going for it.

In Project Street S we'll first apply a variety of basic bolt-on upgrades, the goal no more complex than altering the stock MINI's power, handling and braking for a sportier, faster motoring experience.

To kick off the project, we start with wheels, tires and brakes--which, we might add, are the first three items to consider on any project.


0306ec_streetmini03_z Photo 3/6   |   StopTech's big brake system for the Mini includes a pair of ST40 four-pot calipers and two-piece floating rotors, pads, brackets and stainless-steel lines.

Of primary importance is deciding on the size of brakes you'll want. Then you'll be able to find wheels to clear those brakes, and then tires to fit those wheels.

Our first stop, then, was to StopTech, which has been growing at an amazing rate because of its quality brake kits. Several have been fitted to other european car project cars, including Project BMW M3 and Project Audi S4. And there's rarely a time at a track event that we don't see shiny red or black StopTech calipers on such hot performers as the Audi S4, BMW M3, Dodge Viper, Subaru WRX and Toyota Supra.

The StopTech kit we chose for this MINI features a pair of four-piston ST-40 calipers, two-piece AeroRotor floating rotors (328x28mm), Axxis Ultimate brake pads and steel-braided brake lines. The calipers are painted in black or red, and the rotors can be slotted or cross-drilled. The slotted option may offer slight advantages in strength and durability, and the cross-drilled option results in slightly better cooling and a few ounces less rotating mass. The Axxis pads are street-only, and we found they supply instant bite--no warm-up needed. For the weekend track enthusiast, StopTech also supplies race-specific pads.

0306ec_streetmini04_z Photo 4/6   |   In addition to the three extra pistons per caliper, the rotor is considerably upsized from 276 to 328mm.

Although considerably larger than stock, the StopTech system did not add a debilitating amount of weight. The stock, 276x22mm rotor weighs in at 11.75 lb; the much larger StopTech unit tips the scales at 13.5 lb; and the calipers, pads and lines add only 1 lb per corner and weigh 11 lb. In the end, a per-corner increase of 2.75 lb is a small price to pay for the additional stopping performance.

Once the brakes were fitted, we slapped on a set of TSW Revo wheels, even though a 17-in. wheel probably would have sufficed for clearance, and it would have been a better choice for power delivery through the front wheels. However, wheels are an aesthetic as well as a technical choice, and the car's owner wanted the styling of TSW's 8x18-in wheels. TSW's racing heritage dates back to the '60s, and today TSW wheels can be seen on such Porsche Cup cars as the TSW-sponsored GT2 run by the Freisinger Motorsports team.

Although there was some dispute about the wheel choice for ultimate performance, picking Yokohama Parada tires was a unanimous decision. Sized 225/35-18, the Parada's design features an asymmetric and ultra-low void outer shoulder tread that uses large tread blocks for enhanced traction. Reduced tread squirm, and the large diagonal blocks spread across the width of the tire, are additional components of dry handling performance. An ultra-wide circumferential groove channels water to fight aquaplaning; and helical grooves also help evacuate the wet stuff. Spirally wound nylon reinforces the twin steel belts to augment long-term durability.

0306_05z+mini_cooper_s_sedan+brakes Photo 5/6   |   StopTech conducts real-world tests, as well as collecting track numbers, for each of its applications.

We met StopTech at the test site to put the new brakes and rubber to the test. The first several passes were done with the stock braking system, which performed surprisingly well. (Maybe not so surprising; the MINI is built by BMW, after all.) Stopping tests included 60 to 0 mph, as well as 80 to 0 mph. We also wanted to do a few 100-to-0-mph stops, but the car didn't have the beans to reach that speed within the maximum distance required for testing (we will work on that next).

Generally with a big brake system, noticeably shorter 60 to 0 distances will not be realized, as stopping from that speed is more a function of tire performance. StopTech's goal is to retain, at the very least, the braking distances from the factory system, and also to achieve a real improvement in cooling. This gives the brake system repeatable stopping distances by drastically reducing heat-related performance losses through fluid boil.

From 60 to 0 mph the stock system averaged an impressive 124.78 ft and a best of 122.13 ft. From 80 mph the MINI recorded an average stopping distance of 219.92 ft and a best of 217.17 ft--not bad at all.

0306_06z+mini_cooper_s_sedan+front_right Photo 6/6   |   Project MINI's new TSW "Revo" wheels are 8x18 and easily clear the brake upgrade.

It was time to try the new system. In a flash the technicians installed the new brakes and were off to "bed in" the pads. StopTech recommends ten 60-to-10-mph applications and, if allowable, an additional four stops from 80 to 10 to effectively bed the pads to the rotors.

The first test was from 60 mph. The average of 123.63 ft bettered the stock system by over 1 ft. The best distance was 121.75 ft. Something to note are the variances (differences between longest and shortest distances) in the testing. From 60 to 0, the stock distance varied up to 6.14 ft and from 80 to 0 by 5.42 ft. The StopTech system, on the other hand, varied 4.1 ft in the 60-to-0-mph test and 5.16 ft in the 80-to-0-mph test. Also calculated were 80-to-60-mph stopping distances (information road racers would find useful), which varied 4.97 ft in stock testing but only 2.71 ft for the StopTechs. Consistency is certainly an apt descriptive for these brakes.

Pedal travel from stock has remained unaffected, though the project owner would like to see a little more firmness. He did say, however, that he had yet to encounter any brake fade under full, hard braking on the street from the time these units were installed.

After testing was over, StopTech was pleased to have slightly bettered the factory system, but for its engineers the testing isn't over. They plan to return with additional test calipers to further improve the consistency, stopping distances and pedal feel. By the time you read this, they've probably already accomplished it. Stay tuned.

Braking Tests (Distance in ft)
Stock ST40 w/328x28mm
60-0 mph80-0 mph60-0 mph80-0 mph
128.27 125.85  
126.28 123.96  
124.34 123.06  
124.60  123.58 
124.14 124.28 221.68
125.50 122.64218.53
122.96217.17 123.50220.06
123.84222.59123.50220.40
124.05221.89124.22221.60
122.13219.05121.75216.44
124.21219.19  
125.93219.71  
125.93219.82  
124.78219.92123.63219.79 = Average
122.13217.17121.75216.44 = Best
Note: not enough hp or distance to run 100-0 study
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By Pablo Mazlumian
77 Articles

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