Originally Posted by SkullWorks (Post 427730)

I'm a little taken aback by all the people spewing hate for a proper ducting system,

and claiming that removing dust shield is "just as effective"....wow people I mean really?

Obviously there is a huge benefit to adding cooling to the brakes on this car, Having reached the edge of brake fade on the BRz already, considering the brake fluid has never been touched it is still a dry system, it is clear that there needs to be more cooling for the rotors.

Would the car benefit from higher temp fluid? definitely, but that doesn't mean you wont still boil the fluid, it will just take a longer session,,,a smart man will do both....too bad I like my factory fog lights...

Originally Posted by Kestrel (Post 427760)

if the OP is going to build a brake ducting system in his car "just because"...

Originally Posted by Kestrel (Post 427760)

I'm not "claiming" anything, I've done it, and that's what worked. For a daily driver, you're almost never going to overheat your brakes (on the street), so any brake upgrades are purely aesthetic in nature (putting bigger brakes on has a bigger effect on brake cooling than actual stopping distance).

On a pure-race car, dust shields are unnecessary because there's not a lot of dirt, rocks, tire chunks, and other general shit hitting the rotors as on a street car; race cars also aren't driven for 20,000 miles with the brakes and tires being more or less ignored.

And yes, for MOST track-day situations using street cars in a track setting, removing the dust shields can be just as effective, and is remarkably easier, than doing proper brake ducting. Doing this in combination with a higher temp brake fluid and higher performance pads will lead to even better results than brake ducting on its own.

I'm not "spewing hate" either, but if the OP is going to build a brake ducting system in his car "just because" he ought to know that there are easier, cheaper, and just as effective methods of achieving essentially the same results.

Yes, brake ducting, when done properly (reference any DTM/BTCC team) yields great results, but these are professionally designed, and are used on cars with a MUCH higher performance threshold than the average joe in an FRS is EVER going to reach on a track. A side note, if you're overheating your brakes in an autoX event, you've got bigger problems; not autoX run is ever anywhere near long enough or requires enough braking time that your brakes should overheat.

Originally Posted by JRitt (Post 376385)

Brake ducts on a road car are not a bad idea, you just have to know how to manage them. When a disc is run on the track, the iron expands quite a bit due to heat. When it cools off, it shrinks. The constant heating and cooling, growing and contracting, is what stresses the metal and causes it to crack. Since cooling ducts provide greater airflow and cooling to the discs, they increase the rate of cooling.

Ideally, your discs and pads would maintain a nice steady temperature on the track, without any violent swings upward or downward in temperature. In that situation, the consistency of the brakes would be very good...pads and discs stay at the same temp, and maintain a consistent mu (coefficient of friction). The discs aren't oscillating up and down in temperature, so they aren't as prone to cracking.

Race teams keep a close watch on brake temperatures, and they shoot to eliminate wild swings in temperature. They have a target temperature range based on the pads and overall brake setup they are running for a given track. They can adjust how much cooling air is allowed into the brake ducts, by blocking the duct inlets on the front of the car. If you watch a race at certain tracks, you'll see brake ducts that are partially (or even fully) blocked off.

On a track that is really tough on brakes, you may need as much cooling air as possible, just to keep the brakes in a temperature range where they aren't fading. On a different track however, you may have one very high speed, hard stop, followed by long straights and some low speed stops. In such a case, the brakes would have plenty of time to cool down, even without ducting. If the ducts are wide open, they could introduce so much cool air that the pads don't work as well by the time the car gets back to the hard stop (most race pads don't work great cold...mu varies by temperature), and the discs will get quite a shock going from rather cool (several hundred degrees F) to very hot (possibly 1200F+) during the short time span of that stop. In that case, it would make sense to not use the ducts, in order to keep some heat in the pads and discs during the cooler running portion of the track. That way the upward temp swing isn't as great when you get back to the hard stop, and the pads are already closer to their ideal operating temp.

Also keep in mind that pro race cars have different setups for different tracks. In NASCAR for example, they run heavy duty equipment on a road course like Watkins Glen, whereas on a super speedway that isn't so tough on brakes, they'll run the lightest equipment possible...different calipers, discs, and pads.

For most of the enthusiast, track day, club race guys like us, we don't have the luxury of multiple brake setups. We have one setup, and we have to make it work the best we can. We can use disc paint, which shows the max temp. the discs have reached. Caliper temperature stickers are also available, and you can have a friend check temps with a pyrometer in the hot pits. That is all valuable info to get an understanding of how your brakes are working and the temps they are reaching. Real-time temperature collection is more difficult and expensive.

Then you have to interpret that data based on the tracks you're running and the demands you are placing on the brakes. Are you having any pad fade, are you exceeding the max temps. recommended for the pads you're running, is your pedal getting mushy (fluid fade)??? Then you can decide if you need more or less cooling air, size of duct opening, etc. It's something that takes time and experimentation until you can really dial it in, but every car setup, track, and driver is different. What works for one person in a certain situation, may not be ideal for the next.