How much do brake ducts help?
11-27-2013, 12:28 PM
#1
Le Mans Master
Thread Starter
How much do brake ducts help?
I'm looking to keep the brakes cool, obviously. Do they do much? C6 z51.
I'm trying to use my street car on the track without swapping pads. I got good fluid and hawk DCT-30 pads per recommendation of KNS (though, I'm really wondering if I shouldn't have gone more aggressive here). Problem is my track is hell on brakes. I figure I'll do everything I can and see if it's enough. If not, I'll just swap pads and rotors at the track.
I'm trying to use my street car on the track without swapping pads. I got good fluid and hawk DCT-30 pads per recommendation of KNS (though, I'm really wondering if I shouldn't have gone more aggressive here). Problem is my track is hell on brakes. I figure I'll do everything I can and see if it's enough. If not, I'll just swap pads and rotors at the track.
Last edited by village idiot; 11-27-2013 at 01:59 PM.
11-27-2013, 01:59 PM
#3
Le Mans Master
Thread Starter
I already got the Hawk DCT-30 pads 
edit: how would you recommend I "do it right?"
edit: how would you recommend I "do it right?"
Last edited by village idiot; 11-27-2013 at 02:01 PM.
11-27-2013, 02:00 PM
#4
Safety Car
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If you are going to agressively track your car, the brakes need all the help they can get ! Front ducting will help A LOT in terms of keeping the brakes cool and not boiling the fluid. The BEST high temp fluid - Motul or similar, not just a good fluid. Full track compound pads such as the Wilwood H compound and stailness steel braided replacement brake lines finish out the package. These mods will give you great performing and reliable brakes on a dual purpose street / track car.
Others will dispute this, but in my opinion, just run your track pads all the time. They will work fine for normally driven street usage. I ran Wilwood H race pads for three years on the street in all seasons before the car became an exclusive track car.
Others will dispute this, but in my opinion, just run your track pads all the time. They will work fine for normally driven street usage. I ran Wilwood H race pads for three years on the street in all seasons before the car became an exclusive track car.
11-27-2013, 02:25 PM
#5
Burning Brakes
I do the same, Carbotech 10s on front, 8s on rear, noise doesn't bother me. To the OP, any air you get moving towards the rotor will be beneficial to its longevity, with Spindle ducts probably offering the most. But at the end of the day, rotors will still need replacements more frequently than normal every day driving.
11-27-2013, 03:12 PM
#6
Supporting Vendor
Brake ducts are a HUGE help. I go through this with customers all the time. The vanes in a disc that are properly designed for track use are directional, to move air in a predetermined pattern. They are designed to draw air through the disc and evacuate that air, along with the heat in that air. Along with the vane shape, the number of vanes, the spacing of the vanes, the disc wall thickness, etc. all plays a role. Ultimately however, if cooling air isn't introduced into the center of the disc, those features won't be particularly effective. Again though, the ducts need to force air into the center of the disc so it is drawn into the vanes...not just blow some air in the general direction of the disc and caliper.
One of the biggest benefits of ducts is gaining control of disc temperatures. Wild temperature swings are what cause discs to crack. With ducts and a pyrometer or data acq., you can monitor disc temps, and adjust your ducts accordingly. If you could keep your discs at a constant 900F, they would be more effective...your pads would be more consistent (pad mu is temperature dependent), the discs would be less prone to cracking, etc. With ducts you can tape them over if you want more heat in your brakes, or open them up halfway, or all the way depending on need.
So again in summary...ducts are your friend!
Well, there's your answer. Run pads that are appropriate for the environment in which you'll be using them. It's fine to feel things out, but my advice would be to definitely have something like a DTC70 on hand in case the DTC30's don't get it done for you.
One of the biggest benefits of ducts is gaining control of disc temperatures. Wild temperature swings are what cause discs to crack. With ducts and a pyrometer or data acq., you can monitor disc temps, and adjust your ducts accordingly. If you could keep your discs at a constant 900F, they would be more effective...your pads would be more consistent (pad mu is temperature dependent), the discs would be less prone to cracking, etc. With ducts you can tape them over if you want more heat in your brakes, or open them up halfway, or all the way depending on need.
So again in summary...ducts are your friend!
I'm trying to use my street car on the track without swapping pads. Problem is my track is hell on brakes.
11-27-2013, 03:45 PM
#7
Tech Contributor
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On my C6Z I tried several duct combination. I finally went back to the stock configuration. First, I tried modifying the stock ducts to include the Quantum spindle ducts. This didn't work well since the stock duct outlet was 2.5 inches and the Quantum duct hose was 3 inches. Then I modified the stock ducts by cutting open the 2.5 inc outlet and installing some 3 inch aluminum tube. This resulted in a lot of sharp ends that stuck into the air flow and may have inhibited it.
The next thing I did was take out my foglights and install a set of duct inlets, with a hose connecting them in a Y configuration to the stock duct. I used my leaf blower blowing against the front of the car to test the setup and air did move through the ducts and come out of the rotor. However, on track heat checking and rotor life were not improved. Finally, I purchased a set of LG replacement ducts for the now somewhat well used stock ducts. The LG ducts have 3 inch outlets molded into them but otherwise are almost identical to the stock duct. The Quantum spindle duct hoses run from them to the rotor face. I also replaced the sides of the front air dam as they were quite worn. This seemed to help more than anything else. I think the next thing to consider is the Quantum ducts themselves. If you look at the outlet that is at the rotor face half of the air coming through the duct is probably reflected down and behind the wheel hub as there is a sizeable notch in the tube opening where it joins the backing plate fastened to the knuckle. I can imagine this lets air under any pressure blow out of the bottom of the tube into the area behind the hub.
Bill
The next thing I did was take out my foglights and install a set of duct inlets, with a hose connecting them in a Y configuration to the stock duct. I used my leaf blower blowing against the front of the car to test the setup and air did move through the ducts and come out of the rotor. However, on track heat checking and rotor life were not improved. Finally, I purchased a set of LG replacement ducts for the now somewhat well used stock ducts. The LG ducts have 3 inch outlets molded into them but otherwise are almost identical to the stock duct. The Quantum spindle duct hoses run from them to the rotor face. I also replaced the sides of the front air dam as they were quite worn. This seemed to help more than anything else. I think the next thing to consider is the Quantum ducts themselves. If you look at the outlet that is at the rotor face half of the air coming through the duct is probably reflected down and behind the wheel hub as there is a sizeable notch in the tube opening where it joins the backing plate fastened to the knuckle. I can imagine this lets air under any pressure blow out of the bottom of the tube into the area behind the hub.
Bill
11-27-2013, 05:17 PM
#8
Racer
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I race a 240hp e36. Decent quality curved-vane two-piece rotors and 3" ducting.
I had the same question so I removed the ducting and backing plate from one side of the car and ran a couple of events that way. I'd come in hot and get a buddy to shoot the rotor temperatures with an IR thermometer.
Result: 10%. At the clockwise Sonoma Raceway the ducted side was 600F and the unducted side was 660F. At the counter-clockwise Thunderhill Raceway the ducted side was 700F and the unducted side was 770F.
I had the same question so I removed the ducting and backing plate from one side of the car and ran a couple of events that way. I'd come in hot and get a buddy to shoot the rotor temperatures with an IR thermometer.
Result: 10%. At the clockwise Sonoma Raceway the ducted side was 600F and the unducted side was 660F. At the counter-clockwise Thunderhill Raceway the ducted side was 700F and the unducted side was 770F.
11-27-2013, 05:48 PM
#9
Le Mans Master
Thread Starter
does the Z06 have better ducting than the Z51? Is there a prefered product (that is actually an upgrade over OEM)
11-27-2013, 06:09 PM
#10
Burning Brakes
This is apples and oranges but I can reflect on something that happened to me to indicate ducts help extend the life of the components.
On my 99 Mustang GT with cobra brakes all the way around I had a duct come off at Sebring once on my first session. I was trying a new configuration and having trouble keeping them on. I just ripped both sides off so I wouldn't get another black flag. The brakes seemed to perform normally without fade so I continued to run. Having put brand new pads on all fours I didn't bother checking after each session. You should do that no matter what your experience has demonstrated. The brakes went metal to metal on the 7th session and cut my second day way short. The pads I removed before that weekend were the same brand/compound and had lasted 3 track weekends and a years worth of daily driving and monthly autocrosses and still had meat on them.
At the end of the day I had to replace all the calipers and rotors because I removed the cooling ducts. I think it was about an $800 uh oh moment.
My normal duct configuration is a simple and cheap one. The fog light housings on the Mustang had a 2-1/2" hose outlet on them so I gutted the fog lights and attached shop vac hose to them. I have the rotor end bent to an oval and aimed at the center of the rotor. I just tied off the end at the wheel to the bottom of the strut so all it has to do is articulate up and down, not turn side to side. I just removed the backing plate. This setup has worked flawlessly since 2006 with no more damages other than fluid flushes and pad replacements.
On my 99 Mustang GT with cobra brakes all the way around I had a duct come off at Sebring once on my first session. I was trying a new configuration and having trouble keeping them on. I just ripped both sides off so I wouldn't get another black flag. The brakes seemed to perform normally without fade so I continued to run. Having put brand new pads on all fours I didn't bother checking after each session. You should do that no matter what your experience has demonstrated. The brakes went metal to metal on the 7th session and cut my second day way short. The pads I removed before that weekend were the same brand/compound and had lasted 3 track weekends and a years worth of daily driving and monthly autocrosses and still had meat on them.
At the end of the day I had to replace all the calipers and rotors because I removed the cooling ducts. I think it was about an $800 uh oh moment.
My normal duct configuration is a simple and cheap one. The fog light housings on the Mustang had a 2-1/2" hose outlet on them so I gutted the fog lights and attached shop vac hose to them. I have the rotor end bent to an oval and aimed at the center of the rotor. I just tied off the end at the wheel to the bottom of the strut so all it has to do is articulate up and down, not turn side to side. I just removed the backing plate. This setup has worked flawlessly since 2006 with no more damages other than fluid flushes and pad replacements.
11-27-2013, 06:52 PM
#11
Burning Brakes
11-28-2013, 12:07 AM
#13
Drifting
On my C6Z I tried several duct combination. I finally went back to the stock configuration. First, I tried modifying the stock ducts to include the Quantum spindle ducts. This didn't work well since the stock duct outlet was 2.5 inches and the Quantum duct hose was 3 inches. Then I modified the stock ducts by cutting open the 2.5 inc outlet and installing some 3 inch aluminum tube. This resulted in a lot of sharp ends that stuck into the air flow and may have inhibited it.
The next thing I did was take out my foglights and install a set of duct inlets, with a hose connecting them in a Y configuration to the stock duct. I used my leaf blower blowing against the front of the car to test the setup and air did move through the ducts and come out of the rotor. However, on track heat checking and rotor life were not improved. Finally, I purchased a set of LG replacement ducts for the now somewhat well used stock ducts. The LG ducts have 3 inch outlets molded into them but otherwise are almost identical to the stock duct. The Quantum spindle duct hoses run from them to the rotor face. I also replaced the sides of the front air dam as they were quite worn. This seemed to help more than anything else. I think the next thing to consider is the Quantum ducts themselves. If you look at the outlet that is at the rotor face half of the air coming through the duct is probably reflected down and behind the wheel hub as there is a sizeable notch in the tube opening where it joins the backing plate fastened to the knuckle. I can imagine this lets air under any pressure blow out of the bottom of the tube into the area behind the hub.
Bill
The next thing I did was take out my foglights and install a set of duct inlets, with a hose connecting them in a Y configuration to the stock duct. I used my leaf blower blowing against the front of the car to test the setup and air did move through the ducts and come out of the rotor. However, on track heat checking and rotor life were not improved. Finally, I purchased a set of LG replacement ducts for the now somewhat well used stock ducts. The LG ducts have 3 inch outlets molded into them but otherwise are almost identical to the stock duct. The Quantum spindle duct hoses run from them to the rotor face. I also replaced the sides of the front air dam as they were quite worn. This seemed to help more than anything else. I think the next thing to consider is the Quantum ducts themselves. If you look at the outlet that is at the rotor face half of the air coming through the duct is probably reflected down and behind the wheel hub as there is a sizeable notch in the tube opening where it joins the backing plate fastened to the knuckle. I can imagine this lets air under any pressure blow out of the bottom of the tube into the area behind the hub.
Bill
11-28-2013, 01:39 AM
#14
Le Mans Master
11-28-2013, 10:49 AM
#16
Melting Slicks
I race a 240hp e36. Decent quality curved-vane two-piece rotors and 3" ducting.
I had the same question so I removed the ducting and backing plate from one side of the car and ran a couple of events that way. I'd come in hot and get a buddy to shoot the rotor temperatures with an IR thermometer.
Result: 10%. At the clockwise Sonoma Raceway the ducted side was 600F and the unducted side was 660F. At the counter-clockwise Thunderhill Raceway the ducted side was 700F and the unducted side was 770F.
I had the same question so I removed the ducting and backing plate from one side of the car and ran a couple of events that way. I'd come in hot and get a buddy to shoot the rotor temperatures with an IR thermometer.
Result: 10%. At the clockwise Sonoma Raceway the ducted side was 600F and the unducted side was 660F. At the counter-clockwise Thunderhill Raceway the ducted side was 700F and the unducted side was 770F.
. I'm just a redneck, but what I have done is duct tape around the smaller duct to build it up a little, split the ducting and crimp it over the smaller duct with more duct tape.
12-01-2013, 12:21 AM
#17
Quote:
I'm trying to use my street car on the track without swapping pads. Problem is my track is hell on brakes.
"Well, there's your answer. Run pads that are appropriate for the environment in which you'll be using them. It's fine to feel things out, but my advice would be to definitely have something like a DTC70 on hand in case the DTC30's don't get it done for you."
Ducting helps a lot, but running street pads is a recipe for loading up and going home after 2 sessions on a heavy braking track.
If you run on the track (like your supposed to) you need track pads DTC70's. you don't have to run the hose to spindle ducts (cost/lots of labor) to get decent ducting...run the hose close and wire tie it to the A arm...it works.
get automotive high temp hose and the DTC70's it is a basic track mod to help your brakes live and you have a much better time at the track.
Also, get plenty of cool down time. I've learned that driving around the paddock a little more will keep the rotors from cracking.
I'm trying to use my street car on the track without swapping pads. Problem is my track is hell on brakes.
"Well, there's your answer. Run pads that are appropriate for the environment in which you'll be using them. It's fine to feel things out, but my advice would be to definitely have something like a DTC70 on hand in case the DTC30's don't get it done for you."
Ducting helps a lot, but running street pads is a recipe for loading up and going home after 2 sessions on a heavy braking track.
If you run on the track (like your supposed to) you need track pads DTC70's. you don't have to run the hose to spindle ducts (cost/lots of labor) to get decent ducting...run the hose close and wire tie it to the A arm...it works.
get automotive high temp hose and the DTC70's it is a basic track mod to help your brakes live and you have a much better time at the track.
Also, get plenty of cool down time. I've learned that driving around the paddock a little more will keep the rotors from cracking.
12-01-2013, 12:41 AM
#18
Safety Car
The thing I noticed the most is that the brakes were absolutely 100% there at the end of every straightaway. Even if they got heat soaked in the infield, I could always count on them being ready to rock after a straight. That was my biggest indicator.
12-01-2013, 12:51 AM
#19
Burning Brakes
Also, get plenty of cool down time. I've learned that driving around the paddock a little more will keep the rotors from cracking.
Like Gary2KC5 suggests, run through the parking lot or paddock for a few minutes to keep the cooling airflow over the hot brake components. Likewise I let the engine idle until temps stabilize and start dropping.
Last edited by ZedO6; 12-01-2013 at 12:54 AM.
12-01-2013, 12:57 AM
#20
Safety Car
At the end of our comp school race, the red flagged the field for what seemed like forever, all the while I sit helplessly knowing I'm about to blow a rotor. I allowed myself to slowly roll backward to no avail. At the end of the red flag was a black flag to bring us all in on still screaming hot brakes. Aside from that, the only rotors I've ever popped have been in the pits between runs, and they had cool down laps. On the plus side, a cracked rotor quits shaking once you get it hot. 
