Install: StopTech Big Brake Kit – BMW E46 M3
One of the most overlooked modifications to a car is the braking system. Because it doesn’t yield an immediate acceleration gain, shed any weight off the car, or make your car win an award at a show. But after burying your foot into your right pedal, there is only one thing that keeps you alive and out of trouble: your brakes.
Installing a big brake kit (BBK) offers significantly decreased braking distances, better pedal feel, and a longer lasting system. It’s not a bad piece of hardware to see behind a wheel design either. So when it came time for a friend of ours to revamp the brakes on his E46 M3, he opted for the upgrade to a BBK. StopTech supplied the kit, and R/T Tuning in Montgomeryville, PA handled the install.
After arriving at their new facility, I was directed into the back where the install bays are.
The shop was already lively with customer cars on each of their lifts.
The unopened parts ready for install were already dropped off prior to that morning.
After opening all of the boxes, it was clear to see the potential for shorter braking distances with this kit.
The E46 M3 isn’t exactly a slouch in the braking department from the factory, but this stock setup is destined for a shelf somewhere.
The install began by removing the stock front caliper and rotor.
StopTech mounts their brake kit calipers on a different axis than OEM companies. By creating this application specific hard anodized 6061-T6 billet aluminum mounting bracket, the caliper doesn’t need to be held in place behind the hub and rotor awaiting the mounting bolts. Instead, it slides onto the studs already pressed into their included bracket for a much easier install.
The stock front unit is no match for the massive yellow 6-piston 2-piece fully forged ST-60 caliper. StopTech claims this caliper has the lowest amount of deflection among competitors because of their patented bolt-in bridge, which is strong enough to stop distortion without sacrificing cooling. These stiffer calipers offer less vibration, less noise, faster braking response, and a better pedal feel.
The new 380mm x 32mm two-piece StopTech AeroRotor trumps the OEM piece in size, heat dissipation, and weight reduction.
On some applications, StopTech suggests trimming the stock dust shield to prevent any rubbing with the increased rotor size. This E46 front has just enough clearance allowing it to stay.
Next the AeroRotor rotor simply slides onto the studs, though the OEM set screws can be reused if the car uses lug bolts. The directional, floating AeroRotors allow independent expansion of the rotor and hat without “coning,” thanks to elongated drive pin holes. The aircraft-grade aluminum hats, and 2-piece rotors are up to 8lbs lighter than the stock rotor.
With the caliper then bolted onto the supplied bracket’s studs, and the top bridge removed. You can see the pistons that make StopTech kits so special. Competitors use larger pistons for every application. This can have a negative effect on the pedal feel, if master cylinder and brake lines aren’t changed to compensate for the increased piston size and pressure requirements. StopTech alleviates this by offering application specific piston sizes for each kit, sometimes OEM size or smaller. This creates a stronger brake pressure that the added pistons command.
The 309 compound brake pads are now ready to be dropped in. These pads offer an increased initial bite, with a greater fade resistance. With less noise, and less dust than competitors it’s easy to see why the 309 compounds are supplied with their big brake kits.
The 4 Allen key bolts are then tightened back into place, to secure the cage covering the pads.
The final piece to install on this front section is the braided stainless steel brake lines, which will soon be filled with StopTech STR-600 fluid. These lines are D.O.T. compliant, and improve pedal feel and modulation under braking.
Moving onto the rear brake setup of the car, here is the stock assembly before being removed.
The size comparison here is no different than the front. The yellow 4-piston forged rear ST-40 caliper from StopTech is much larger than the stock piece.
With the rear rotor assembly removed, it was pretty clear the dust shield would interfere with the brake kit.
There is a small lip on the shield, just outside the emergency brake shoes. This would provide the perfect template to trim away the intrusive section of dust shield.
After several layers of protective material were applied to the exterior of the car… It was time to cut!
Using a grinder, cutting wheel, and air compressor it took just about a minute to remove the shield.
The exposed cut metal would need to be coated in paint to prevent rusting.
The new caliper bracket is then tightened onto the rear knuckle.
This comparison between OEM and the 355mm x 32mm 2-piece StopTech AeroRotor shows the size difference.
The rear rotor is then placed on the studs, and the caliper is slid onto the new bracket, revealing the piston size.
Next, the 309 compound pads are dropped in, OEM rear brake wear sensor attached, and the bridge is fastened.
The supplied braided stainless steel brake lines are connected and will be filled with STR-600 fluid when the brake system is bled.
Here is the finished product! Upgrading to a larger rotor and caliper size usually means moving up a wheel size or two. To accommodate the new brake system, a staggered set of mold forged 1-piece Advan GT wheels in Racing Metal Black with machined lips were sourced from Mackin Industries.
Measuring 18” x 10.5” ET24 in the rear and 18” x 9.5” ET22 up front, they are the perfect aggressive yet understated addition to the exterior of the car. With 5 different concave face options available, the rears are the highest inset ‘Concave-5’ option to allow maximum clearance for the new brake setup.
As you can see, the Advan’s also showcase the new StopTech BBK perfectly.