The Wilwood AERO4 rear big brake kit bolts to the OEM rear axle and reuses the factory parking brake assembly, pairing forged four-piston W4AR calipers in black powder coat with 14.00-inch GT slotted rotors to add stopping capacity behind 18-inch and larger wheels on the BMW E90 325i and 328i. The Spec-37 iron rotors run a 72-curved-vane internal design with a black electro-coat finish, and the kit ships with BP-20 compound pads, parking-brake mounting hats, and a rear stainless flexline kit. Caliper output is matched to the OE master cylinder, ABS function, and factory brake bias.
| Type | AERO4 four-piston rear big brake kit for OE parking brake |
| Position | Rear axle |
| Caliper | W4AR forged AERO4 4-piston, black powder coat |
| Rotor | 14.00 in (355mm) GT slotted, Spec-37 iron, 72 curved vane, black electro coat, 1.10 in thick |
| Pads | BP-20 compound |
| Contents | Calipers, rotors, parking-brake mounting hats, BP-20 pads, mounting hardware, rear stainless flexline kit |
| Min. Wheel Diameter | 18 in |
| Quantity | Complete rear axle kit (pair) |
| Part Number | 140-13583 |
Documents: Installation Instructions (PDF)
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2006 | BMW | 325i | Base |
| 2007-2013 | BMW | 328i | Base |
Shipping: In-stock orders placed before 3 PM EST ship the same day, and everything else ships within 24 hours. Standard, expedited, and overnight options are available at checkout. Backordered items ship as soon as we get them back in stock. Contact us for lead times. See the full Shipping Policy.
Returns: 30-day returns on new, unused items in original packaging. See the full Refund Policy.
