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Skip Navigation Links. Installing Brake Ducts On Your E30 M3:

by Roger Ness

I purchased the brake duct kit advertised by Bill O'Neill in the Roundel (Daytime 715/275-4023, Evenings (716/533-2333). This kit includes the backing plates, ducting hose and spoiler ducts. The kit price is $355 or you can purchase just the backing plates for $250. The kit is well designed and everything fit perfectly. Directions are provided and the only thing we did differently was to fabricate an extra clip for each duct (his setup only has one clip per duct).

Installation is pretty straight-forward. The most difficult part is removing the existing backing plates. This requires removal of the caliper, rotor and hub. You'll need an air wrench to loosen the nut and a wheel puller for extracting the hub. Be careful not to lose any of the wheel bearings. Also, you'll want to have some grease on-hand to re-pack the hub.

I was amazed that the entire front spoiler is only held on by two nuts and can be removed in about five minutes

How do they work? Our first big test came during a driver's school at Gingerman. The weather was hot and the weekend ate up a new set of pads, the left front wheel bearing, left front tire and (gulp) the rod bearings. Last year at the same track, in same conditions, I warped a set of rotors. The rotors stayed cool and the pedal never faded. However, the undertray cut into, and destroyed, the ducting hose. I've since removed the offending "body work".



Before


After


The modified backing plate