Brake Ducts for 20 Bucks

My first track day my brake pedal started getting squishy the 2nd session, and by the 3rd session I had to cruise slowly through the hot pits each lap to cool my brakes. The brake fluid was permanently ruined, even though it was racing brake fluid I had recently flushed. I decided to put on some brake air ducts before doing another track day.

Safety warning: If you do nothing else before a track day, you need to flush your brake fluid beforehand with a good racing brake fluid, like ATE, Motul RBF 600, or Castrol SRF. This will raise the boiling point by 100 or more degrees, and will get rid of fluid that is likely old and waterlogged.

I bought 3 inch heater duct and 4 large hose clamps from the hardware store. I also used a few zip ties. I was careful to get high temperature foil ducting. Plastic dryer ducting would melt.

The first step was to remove the plastic panels under the car, and remove the fog lamps. The ducting was just the perfect size to tuck into the fog lamp hole. An improvement would be to seal the open half of the hole. This seems to be the feature that most interests other racers, I have even had people take pictures. The car appears to be 100% stock otherwise.

I used a baggie to seal the electrical plug, in case I wanted to reinstall the foglamps. I zip tied it out of the way. The next pic is looking up from beneath the car. Many brake duct installs just run completely under the car -- this has the advantage of being easier, and the duct paths perhaps a little shorter and straighter. My ducts live mostly above the plastic panels (removed in this photo), so there is less danger of scraping them off. Also, they then do not interfere with air meant for the radiator; the Camaro pulls the air from under the car.

I used a hammer and a chisel on an iron plate to cut a hole through the fender liner for the duct.

These pics show how I routed the duct above the sway bar. You can read about my sway bar installation here: http://www.explodingdinosaurs.com/swaybar . This worked great on the right side of the car. The left side had a cable (I think the hood release) that squished the duct above the sway bar, so the left duct droops below the sway bar instead (3rd picture below).

The brake end of the duct is held only by 2 hose clamps. Look carefully below the upper hose clamp to see how it is held to the suspension arm by the lower hose clamp. More serious ducting jobs use a metal piece instead, that puts the air outlet very close to the disk, and forces air through the center of the disk better. My hose ends aren't super close to the disk. An upgrade would be to fabricate a sheet metal tube, carefully cut to blow air into the center of the brake disk with little clearance to the brake disk.

So did it work? Yes! On my 2nd track day I was driving much faster, due to more experience. I was also going faster because I had race tires instead of street tires. I almost made it through the whole track day, but had a little bit of a squishy brake pedal on the last 3 laps of the day, and the brake fluid was ruined and had to be flushed. I fixed the pinched duct, and on my 3rd track day was able to make it the whole day, and didn't have to flush the brake fluid afterwards, although the pedal is a little softer than before. I will flush the brake fluid before doing another track day.

I'm only doing one track day a year at this time. I run the car in F-Stock in http://www.scca.com autocross, so I wanted to keep the brakes stock (technically the brake ducts throw me out of stock class, but as there is no performance benefit at autocross speeds, I don't expect any complaints). If I were going to get serious about the track I would install much larger Corvette brakes, and a larger radiator.

This chart gives a synopsis of my car's track brake history.

	1st Track Day	2nd Track Day	3rd Track Day
Equipment	Rock hard street pads, Motul RBF 600 Brake fluid, BFG KDW street tires	Brake air ducts (one duct pinched), Hawk HPS brake pads, Motul RBF 600 Brake Fluid, Hoosier R6 race tires	Improved brake air ducts, Hawk HPS brake pads, Castrol SRF brake fluid, Hoosier R6 race tires
Track	MMP outer track, very fast	MMP East Track	MMP West Track
Performance	Brakes very soft, had to cool them by going slowly through the hot pits most laps	Brakes started going soft the last 3 laps of the day	Brake pedal a bit softer, but held up the whole day
Equipment Damage	Front disks heavily scored, front bearings need replacement, brake fluid ruined	Front disks heavily scored, new front brake pads were 50+% worn away, front bearings need replacement, brake fluid ruined	Front pads about 25% worn
Comments	The brake fluid was not even up to an autocross after the track day!	The brake fluid was not even up to an autocross after the track day!	Also drove the car on the street about 2 miles after each session, and watered down the brakes between sessions. The air temperature was near 100 F (35 C). I consider it a success I made it the whole day, and the front brakes and bearings survived, even though I was driving faster. I was also very happy I could do another track day just changing brake fluid, instead of also having to change the front pads, disks, and bearings.

MMP = Miller Motorsports Park, http://www.millermotorsportspark.com

Some further comments and caveats:

Camaros are hard on their front bearings on the track. I think the ducts helped keep things cooler and helped the bearings survive.
My track day comparisons are not perfectly apples-to-apples, since the temperatures, track configurations, and my skills were different.
MMP is very hard on brakes, there is a straightaway before most turns. Other tracks may not be as hard on brakes.
I use cheap ($21) Autozone disks. Many folks have had drilled or slotted disks crack. Amazingly, these Autozone disks have never warped, despite the high heat and heavy use, and they are cheap enough I just throw on another pair after a track day.
Check with folks that have tracked a car similar to yours before hitting the track, to know your car's weak points.
Know how far down your brakes go, so you can tell if the pedal starts getting lower.
My ducts were cheap and helped alot, but you can get ducting kits that I imagine would do a better job.
My ducts are pretty fragile, and turning the wheel all the way tends to chew them up. They are cheap enough, though, I just throw on a new section of hose for the wheel well part before a track day.

Many thanks to the guys at the F-body Road Racing and Autocross board for all their great advice! (F-body = Camaro or Firebird)
http://www.frrax.com

You can read about more of my car adventures here:
http://explodingdinosaurs.com