BMW E46 M3 Upgrade: StopTech’s New Fifth-Gen Trophy Big Brake Kit

Our most loyal readers will remember an article we published over five years ago(!), which featured the installation of StopTech’s 6- and 4-piston Big Brake Kit offered for a range of models, including BMW’s E46 M3. For the rest of you, we went to R/T Tuning in Montgomeryville, Pennsylvania, again, covering not only the exact same car but the exact same installation. Right now, you’re probably asking why? Well, because as time progresses, so, too, does the automotive aftermarket and its solutions. The folks at StopTech have been hard at work improving their kit, and we felt our article needed updating. We want to introduce the fifth-generation StopTech Trophy Big Brake Kit in its signature nickel finish. Let’s go over what makes it such an improvement over the company’s past iterations.

The first thing we noticed was the impressive nickel finish. In our previous article, we recounted one of the colorful offerings from StopTech for their base BBK, which included the builder’s choice of blue, red, yellow, or silver calipers. Shortly after, the company released a special grey anodized finish on its top-of-the-line motorsport-based Trophy kit calipers. However, there was a downside to the trick performance-oriented finish on their premium lightweight kit. The final anodized grey color differed from front-to-back, side-to-side, and even half-to-half on each caliper in any given kit. It took some trial and error for StopTech to find a solution to this issue, but they eventually got it nailed.

On the new system, a unique, innovative nickel finish now envelopes the calipers. The reflective surface shines and glistens quite perfectly when any light hits it and eliminates discoloration potential between products. Each caliper’s plating matches the next, which is a big aesthetic step for this kit. The only piece of the fifth-generation Trophy kit that still utilizes anodizing is the black anodized bridge. StopTech carried the same bridge construction concept from the previous BBK model but refined it by building it to distribute stress more evenly.

Using a multitude of different methods, StopTech made equal improvements to stress distribution, stiffness gains, and overall cycle fatigue characteristics. The company increased efficiency, saved weight, and improved rigidity through the kit’s hardware. Yes, by eliminating the crossover bolt-and-nut configuration of past kits, the engineers shortened the hardware, simplified its construction, and increased stiffness. These improvements prevent deflection across the caliper’s body, and the result looks a bit more like a monoblock design.

Along with the new bolt design, the caliper’s backside became the source for construction using inboard hardware. Where past kits featured bolt-and-nut combinations starting on the exterior, the inboard layout hides the hardware, prevents rusty hardware from being exposed on the outside, and keeps a cleaner appearance across the board.

On the actual machining of the product, significant weight reduction was a key element throughout its design. StopTech optimized the fifth-generation caliper body profiles for weight, removing material in certain areas, and generating an overall sleeker design. The new STR60 6-piston Trophy kit weighs 3-percent lighter than the previous iteration, with a low-end weight of 6.7 pounds and a high-end weight of 7.68 pounds — depending on the application’s piston size. That, coupled with 5-percent weight savings on the STR40 4-piston rear caliper used on this E46 M3, and we’re looking at an adequate 8-percent weight drop over the fourth-generation Trophy kit — let alone the savings over the base system.

Onto the rotors, the new bi-directional slot design elevates this setup to new heights. The proprietary pattern’s minimalist looks whisk away contaminants — whether gaseous or solid — and give the pad surface extra bite on the rotor. It’s an elegant solution to the typical slot design found on sport brake rotors. This particular kit features massive 380x32mm front rotors tucked inside the STR60 caliper, while the STR40 slows a large 355x32mm rotor in the rear.

Thanks to the well-engineered fifth-generation kit, the install itself is pretty straightforward, especially when you consider that one of the company’s BBKs already occupied the wheel wells. The R/T Tuning team removed the old caliper and rotor from the hub, cleaned up any areas making contact with the brakes, washed the new rotors’ surface, and installed the latest goods. Because this kit includes new stainless steel braided brake lines, the old set remained fastened to the yellow calipers while R/T Tuning outfitted the new equipment.

Installing the new StopTech Sport brake pads was made easy by utilizing the removable black anodized bridge. You can even see the snug resting place for the OE BMW brake sensor. With rotors, pads, calipers, and lines all installed, the last step was to bleed the braking system using racing brake fluid.

Overall, this is a classier, lighter weight, stiffer, and better-performing alternative to what StopTech has offered in the past. Applications are still in the process of being worked out, but we can already see this kit being a standout in its class. If you drive a sports car like the M3, NA1/2 NSX, Supra, S2000, FR-S/BRZ/86, or Mustang GT, be on the lookout for these kits to hit shelves soon!

Photography by Brandon Cody and Jason Reiss