Project E39 M5, Part 1: Stopping the Ultimate Driving Machine


With the front bumper removed you can see these metal tunnels that guide the air forced into the brake ducts to the front rotors. All E39s come equipped with these metal tunnels. Opening the holes on the grill is simply not enough to direct the amount of air necessary to make a significant cooling difference. The opening of the tunnels sit more than 8 inches away from the sink drain holes, so any air scooped by the sink drain holes will just get dispersed everywhere but where we want it to go. 


That's where the plastic brake ducts come in. They simply slide right into the metal tunnels and when the bumper goes back on, it will place the sink drain right inside of the plastic duct. This will allow all air forced into the sink drain hole to go into the brake duct, through the metal tunnel… 


…and out the other side of the metal tunnel which sits right behind the brake rotor.


This is what the finished job will look like once the 540i fender liners are in place. Why the M5s did not come with these brake ducts from the factory is beyond me. If you track your E39, M5 or not, we highly suggest performing this mod. 


Here is the Slimmbones grill compared to the old stock lower grill. Since the Slimmbones grill begins as a brand new OE E39 M5 grill, fitment is perfect and it is also a nice facelift. The old grill's looks had become faded and worn from years and miles of use.


With the front bumper in place you can see the uninterrupted path cooling air will have from the front of the car to the opening leading to the back of the rotor.


1 comment

  1. What are the part numbers and where did you source the:
    – brake ducts
    – pork chop with duct slot. Wheel well liner.

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