DIY Brake Cooling

[Roy]

Ok, hoping i can rely on those with more experience in this area then myself.

This weekend im going to measure up the front of my car and suss out the best way to get some ducting to my front rotors.

I know that you have to be sure to direct airflow perpindicular to the very centre of the rotor. I understand if i direct the airflow to a section of the rotor istelf then it can encourage warping as the rotor will have a hot spot (caliper on rotor) and then a cool spot where air is ducted onto the rotor. (Or in practice isnt it that critical?)

So, two questions, im thinking of using a NACA duct in the undertray of my car to feed air to the rotor, or, duct air from cut outs in the inner guards.

My concern with the 2nd approach is that from side to side the cooling could be different as the intercooler pipes, oil cooler and cold air inlet pipes will mean different air flow side to side.

So im leaning towards thw NACA ducts as i should be able to position them under the car where they will flow even amounts of air to the respective rotors...ppl thoughts?

The second question is with the stub axle being in the centre of the rotor, how do i go about centreing the duct outlet, and what is the best means of locating the duct to the stub axle (Steering knuckle or whatever you want to call it)

Memory has it that its pretty light in there with the the control arms, stuc axle shock absorber/spring.

Measuring the brake temps is cool as i have a means of measuring the rotor temp to see if its doing anything.... just need to know how to go about it....Anyone?

[KamikazeR33]

i would have thought in principal that the best spot to duct cooling to the rotor would be the section just after the brake caliper (in this case would be the lower part of the caliper) effectivly cooling it after its been heated... i doubt there would be too much warping as ud be constantly using the pedal to keep it from warping

kind of same principal as with a fmic in terms of cooling

correct me if my thoughts are incorrect

[blind_elk]

Why not duct onto the caliper itself? You have vented rotors, and if you have good quality pads, then there shouldn't be a major drama. Duct onto the caliper to help keep the brake fluid cool.

And remove the backing plates.

[Roy]

Remove the backing plates of the pads???? What are the advantages.

Yeh sure brakes are vented, the air circulates from the inside out, so ducting air to the caliper aint really a fix, especially with the pads and fluid i run. Im more concerned about trying to keep rotor temps in check.

[Duncan]

Roy, as you know I generally don't know what I'm talking about and this is probably no different.

But, I thought you were meant to aim the brake ducting from behind the hub to the inside for the disc, and then the air flows outwards from there. ie you don't aim the duct at the disc at all

[Roy]

lol, isnt that what i said, " be sure to direct airflow perpindicular to the very centre of the rotor"

I have one piece rotors, so centre of rotor is the centre of the hub. Ya folla, or should i up my meds?

[Duncan]

ahh yes, read they question, I see

[David Kemps]

yeah u direct flow to the centre and it flows outwards thru the ventilation part inside the disk.

u can use infra red sensors to measure temperature.

Dave

[red900ss]

lol I knew exactly what you meant Roy.

I don't think you'd have to worry about the hot "ring"/cool "ring" on the disc (not really a "spot"). As long as the inlet point (of the disc) is getting a decent volume of air to do the cooling job you'd see a benefit in overall lower temps.

As for NACA ducts they wouldn't get as much flow a hose presented inline with the direction of relative air flow. The amount of drag from a hose v. a NACA duct not really an issue on our cars.

[blind_elk]

Remove the backing plates of the pads????

No, the backing plate from behind the rotor itself.

What are the advantages.

Opens up the other side of the rotor to cooling air, probably also gives a good access point to duct air into where you want to duct it.

[Sydneykid]

Hi Roy, I'll dig around and find a V8Supercar brake ducting picture and post it up. Until then....

They have 2 ducts for each wheel. They both feed off the hole at the side of the radiator inlet. One duct goes to the centre of the disk via a fadricated steel vent that is attached to the upright, so it goes up and down with the suspension. The other duct is also attached to the upright but it points at the calliper. The disks are full floaters of course, but the same principle applies to a one piece rotor, they have the inlet to the vanes on the inside.

As for Skylines, we don't find brake temperature to be much of a problem. As previously posted I always remove the backing plates both front and rear. We use Hawke carbon pads in the blue compound, so they work very well up to 700 degrees C. At the end of a 20 to 30 minute race the limiting factor on stopping is tyres ie; the braking power still exceeds the grip of the tyres. We run flat undertrays and they have alloy deflectors that help direct the airflow, from the lower inlets on the GTR N1 front bumper, to the inside of the front wheels. Not ducting, more like a fence. Crude but effective, if you point an air hose into the vent, you can feel the air come out through the front wheel.

Hope that helps

[Roy]

Without looking at my car, i think i already have removed the backing plates becuase im running 330mm rotors. I was swapping over rotors on a friends R32 GTST and having a look at how to improve the breaking ability.

Well it looks like i have taken reasonable meaures already, so see how it goes at Sandown.

I already have plenty of pics of V8 Supercars, Le Mans cars, GT Cars, Super Tourers etc, so have a reasonable idea of how to go about directing the airflow. LOL, but they dont look as crowded in there as my road car:)