The Wilwood AERO4 Big Brake Rear Axle Kit replaces the factory rear disc brakes on the BMW E90 325i and 328i while retaining the OE parking brake assembly, pairing with a front big brake upgrade. It uses forged AERO4 four-piston calipers in a red finish, BP-10 compound pads, and oversized 14.00 in. x 1.10 in. SRP drilled and slotted rotors, all sized to work with the OE master cylinder output, ABS function, and vehicle brake bias. Braided stainless steel brake lines are included.
| Type | AERO4 rear big brake kit (retains OE parking brake) |
| Position | Rear |
| Caliper | AERO4 (W4AR) forged 4-piston, red finish |
| Rotor | 14.00 in. x 1.10 in. SRP drilled & slotted |
| Pads | BP-10 compound |
| Contents | Calipers, rotors & hats, pads, mounting brackets, braided stainless brake lines, hardware |
| Quantity | Complete rear axle kit (both sides) |
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2006 | BMW | 325i | Base |
| 2007-2013 | BMW | 328i | Base |
