Brake duct pics, ideas.
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From: Gardena
FYI, when I installed my carbon fiber ducts I removed the splash guard for the front rotors. Its been 5-6 months and no regrets, its always nice to find free useful mods (the splashguards, not the carbon fiber ducts obviously). 
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From: On the lakefront...
The only way to effectively deal with the sheild as it relates to blockage of wind flow is to use a welding tool to cut out the area off the shield, then apply the duct to the shield. Cooling off the rotor shield won't do squat. The air needs to be directed onto the rotor itself.
That is how King did Nick's car...fyi.
That is how King did Nick's car...fyi.
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<<Cooling off the rotor shield won't do squat. The air needs to be directed onto the rotor itself. >>
And:
<Dunno if I agree with that. If the rotor shield is there to dissipate heat, then cooling the shield should be as good as cooling the rotors.>>
You don't cool the discs by cooling the splash shields. You need to cool the rotors. Ideally in a manner which cuts heat from both sides of the disc evenly so as to reduce the tendency to warp due to differential expansion (side to side). The easiest way to do this with a vented disc is to direct air into the hole on the back of the rotor, the "eye". Not just through the splash shield. Many race cars use the approach invented and developed by Colin Chapman for Lotus. A plate seals the eye of the rotor and a hose passes through this eye so that cooling air can only escape through the disc's vanes. On many cars, such a cooling method will cut the temps 3-400 degrees fahrenheit. Often this alone leads to 3-8 times more brake pad life!!
At track events, most of the tendency to warp occurs when you park the car. Most of the rotor cools evenly except for the part under the pads which stays much hotter much longer. Another differential expansion / contraction issue. Try to drive around awhile and use little braking on your cool down lap. Many folks roll the car forward or back 3 feet after a couple minutes to get the hot part of the rotor out into the air since the tire circumference is around 6 feet.
Stan
And:
<Dunno if I agree with that. If the rotor shield is there to dissipate heat, then cooling the shield should be as good as cooling the rotors.>>
You don't cool the discs by cooling the splash shields. You need to cool the rotors. Ideally in a manner which cuts heat from both sides of the disc evenly so as to reduce the tendency to warp due to differential expansion (side to side). The easiest way to do this with a vented disc is to direct air into the hole on the back of the rotor, the "eye". Not just through the splash shield. Many race cars use the approach invented and developed by Colin Chapman for Lotus. A plate seals the eye of the rotor and a hose passes through this eye so that cooling air can only escape through the disc's vanes. On many cars, such a cooling method will cut the temps 3-400 degrees fahrenheit. Often this alone leads to 3-8 times more brake pad life!!
At track events, most of the tendency to warp occurs when you park the car. Most of the rotor cools evenly except for the part under the pads which stays much hotter much longer. Another differential expansion / contraction issue. Try to drive around awhile and use little braking on your cool down lap. Many folks roll the car forward or back 3 feet after a couple minutes to get the hot part of the rotor out into the air since the tire circumference is around 6 feet.
Stan
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From: WA
The splash guard mounts to the steering knuckle so I would guess that it is not extremely effective in dissipating heat, the primary function is protection.
A good point regarding the wheels. They are in fact the largest dissipater of heat and I bet some designs and materials are more effective than others.. I never thought much about the wheel being a heat sink until now.
I know the M3 has brake cooling built in without ducting directly to the rotor.. does it have large vents in the splash guard? Who has had the front wheel off their M3 recently?
Looks to me that the biggest advantage to running duct to the back of the (modified) splash guard is that you maintain rotor protection while increasing airflow. Otherwise you can either remove the splash guard, blow air at the limited vent openings, or maybe modify it to increase the open vent area.
I
A good point regarding the wheels. They are in fact the largest dissipater of heat and I bet some designs and materials are more effective than others.. I never thought much about the wheel being a heat sink until now.
I know the M3 has brake cooling built in without ducting directly to the rotor.. does it have large vents in the splash guard? Who has had the front wheel off their M3 recently?
Looks to me that the biggest advantage to running duct to the back of the (modified) splash guard is that you maintain rotor protection while increasing airflow. Otherwise you can either remove the splash guard, blow air at the limited vent openings, or maybe modify it to increase the open vent area.
I
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<<The vents in the splash guard are angled to direct air to the center of the rotor so that it would be exhausted through the vanes. Clearly this is the area where air flow should be directed.>>
It sounds like this does not seal to the eye of the disc. Which means that cooling is reduced and that some extra cooling occurs on the inner disc surface compared to the outer surface which is not good if the car is tracked alot.
All M3s have splash shields. No street cars come with the sort of duct I described. Many BMWs (not just M cars) come with simple brake cooling enhancements such as air deflectors which attach to lower suspension arms. Not only is the eye duct important but some also add ducts to the inner and outer surfaces, even the caliper itself. You also need as large a diameter and as straight as possible a duct from a high air pressure area of the car upstream of the brakes.
Simply removing or cutting off splash shields cuts heat. You can leave some of it on to shield joints from heat if that is a concern. Or use the shiled as a starting point or attachemnt point for proper ducts.
You can also improve driving skills such that less braking is required.
Ducting is really not needed on the street if your brakes are halway decent. And it's often a good idea to disconnect it for normal driving.
Stan
It sounds like this does not seal to the eye of the disc. Which means that cooling is reduced and that some extra cooling occurs on the inner disc surface compared to the outer surface which is not good if the car is tracked alot.
All M3s have splash shields. No street cars come with the sort of duct I described. Many BMWs (not just M cars) come with simple brake cooling enhancements such as air deflectors which attach to lower suspension arms. Not only is the eye duct important but some also add ducts to the inner and outer surfaces, even the caliper itself. You also need as large a diameter and as straight as possible a duct from a high air pressure area of the car upstream of the brakes.
Simply removing or cutting off splash shields cuts heat. You can leave some of it on to shield joints from heat if that is a concern. Or use the shiled as a starting point or attachemnt point for proper ducts.
You can also improve driving skills such that less braking is required.
Ducting is really not needed on the street if your brakes are halway decent. And it's often a good idea to disconnect it for normal driving.
Stan