Custom Brake Cooling Ducts

[Boss_Hoss]

Last year I took my F80 to COTA, a track notorious for cooking brakes, and decided I definitely needed to put some direct cooling (and why BMW decided to skip them still puzzles me). Nothing on the market appealed to me, and not to mention pretty overpriced, so I designed my own that sit nicely below the bumper. I have since sold my M3, to much sadness, but I decided I wanted to share with the community in case someone out there can benefit. Note that they are not perfect; they definitely need more work, but unfortunately I can't invest any more time into a platform I don't own. If someone out there wants to take it and improve it, be my guest. I am sharing this work under Attribution-NonCommercial-ShareAlike CC BY-NC-SA.









Below are all the resources I used for this project. I have also attached a PDF showing the installation. The STL files for printing can be found here: https://www.printables.com/model/173...ing-duct/files

Note that you will have to print the mirror image as well, which can be done in any slicing program. I recommend printing out of either Polycarbonate, or high strength Nylon. I also added a thin gauge sheet of aluminum to act as a "skid plate" that was just epoxied to the bottom. Also if it wasn't obvious, you will have to cut off the rubber flap; if yours is still there, kudos to you (mine sheared off two weeks into ownership).

Whatever you do, do not print it in PLA or PETG, it will crack the second you put it on the car. You need to use something that is strong and impact resistant.

The three pieces will have to be epoxied together afterwards, which might need some sanding and polishing. As you can see in the PDF, they took some hits. Thankfully they survived the track just fine, even riding the curb a couple of times, but on the way back home they took a couple of hits that ultimately cracked them. I should have taken them off at the track before leaving but I didn’t have the time or energy.

Below are all the links you need to order the hose and flanges, as well as instructions for drilling and mounting the flanges.

These are the flanges you want to order. 2.5”
https://www.aircraftspruce.com/catal...uctflanges.php

This is the ducting I used. I ordered 10 feet, it was way too much. You only need 6 ft (my hoses were 32” long per side)
https://www.aircraftspruce.com/catal...ickkey=5280563

This post shows how to drill and mount the flanges:
https://f80.bimmerpost.com/forums/sh....php?t=1592917

some extra reading for you:
https://f80.bimmerpost.com/forums/sh....php?t=1232532
https://f80.bimmerpost.com/forums/sh....php?t=1379690

[sly1types]

nice work

[FrankMstein]

Sooo how did these stand up, especially on track curbs?

[4Y_stack_acceleration]

What pads and rotors were you running that were getting overheated?