Brake rotor cooling

[Sam McDowell]

My GTD has NO air directed into the brake rotors. As a result I cooked a set of front rotors at Road Atlanta last month.
Does any one have design that will help me get some cooling air?
Sam

 

[Jeff Young]

If you are vented, you want to get air to the center of the rotor. Check some of the NASCAR supply shops for what are called spindle ducts. If your brakes are some sort of standard Wilwood setup you can probably find something that bolts right on.

For the inlet ducts, get them as close to centerline on the car as possible.

 

[Tim Kay]

For the inlet ducts, get them as close to centerline on the car as possible.

I did not know this, I can assume, but please educate and elaborate why.

Thanks,
Tim

 

[DaveM]

I'm not familiar with GTD front rotors, but this shows ducting on an SPF. Doubt you will be able to buy anything off the shelf. If you have access to a TIG or MIG welder fabricate your own ducts. You need to get air funnelled to the center of a vented rotor to be effective.
http://www.gt40s.com/forum/attachment.php?attachmentid=46063&d=1270518033

 

[Seymour Snerd]

These looks like they might at least be a start....

http://www.amazon.com/Allstar-Performance-ALL42116-Lightweight-Spindle/dp/B003C01BTO

Genesis Technologies Carbon Fiber Race Car Spindle Brake Ducts: Genesis Technologies Race Car Parts and Equipment

 

[Terry Oxandale]

I did not know this, I can assume, but please educate and elaborate why.

Thanks,
Tim

I believe this is related to the way the air will flow over the shape of the area adjacent to the inlet. The center of the body has the least whole diversion of air as it prepares to move around an oncoming moving body. This situation can be overcome fairly easily with small fences on the sides of the inlet in which the air is likely to be moving across the inlet, rather than straight into it. I've attached a photo of a non-GT application in which the fencing increased the effectiveness of gathering air significantly (as measured with a manometer). I had to do this because much of the air was simply bypassing the duct and flowing past it to the side and under the bodywork. Simply having a hole is no guarantee that something will go in it.

 

[Jon Briggs]

Weren't the openings either side of the radiator inlet provided for this precise reason?

 

[Howard Jones]

You need to tell us what exact type of rotors/calipers/pads you have on the car. If you still are running the granada "stock GTD" rotors and calipers then they are not suitable for track work. Mine lasted about 3 laps and the pads were burnt to a crisp many years ago.

On the other hand I have a wilwood setup on my car now that are not directly vented and have done just fine being flogged rather hard in very hot weather without heat related problems.

Show us what you got, so we came help you. Pictures help a lot.

 

[Jim Cowden]

I did not know this, I can assume, but please educate and elaborate why.

Thanks,
Tim

Tim the rotor is a turbine so to speak and draws air in the centre and forces it to the out side through the vains.

Is that what you wanted to know.

Sam you need to monitor rotor temps then you pick a pad to suit.
If you are up it you would see at least 550-600c I would think.
Ferodo ds 2500 work well and stop good cold as well, DS 3000 not very streetable and are in the 650-800c range I think.
Thats what some of the other guys are refering to ,you pick a pad to suit the climate

Jim

 

[Cliff Beer]

What kind of rotors are you using? sizing....diameter, width, vented? If you're not using a vented rotor then that's the first thing to fix. If you're using a vented rotor of slender dimensions then that's the second thing to fix. Then, after that, look for greater cooling with some ducting...

 

[Sam McDowell]

Wow. Great information.
I have learned that the front brakes are a JFZ 4 piston caliper. Rotors are 12.19" x 1 1/4" 8 bolt on 7 3/8" (?). I found a shop that ordered me a set.
Incuded here are some pictures. What I am trying is to make a fiberglass duct that fits between the radiator frame and head light box and up to the scoop to the side of the radiator inlet.
I have a 1 1/2 " space to work with, so my duct is 1 1/2 x 9", 13 sq in. I don't have to cut anything.
I am using aircraft foam as a core, which is easy to sand into shape then clean out with a rotory wire brush. It has to be in two parts, one in the nose and one on the body shell. I will then connect a 3" hose to direct the air into the center of the rotor.
I live near Mooresville NC where are more racing supply shops than you can imagine. I think I can find that duct pictured here.
Does this look feasable?

 

[Seymour Snerd]

Here's a Wilwood article on brake system cooling:

http://www.wilwood.com/Pdf/DataSheets/ds254.pdf

 

[Sam McDowell]

Good article.:thumbsup:
Thanx
How is the best way to check rotor temps? I have seen those infared temp sensors. Would they work? Should the front and back temps be the same or close if the brakes are balanced?
Would the temps be valid after the cool down lap?
Sam

 

[Eric A.]

One of the brake books that I have shows using temperature sensitive paint to check the temps. You apply paint with several different temperature ratings and see which one melts. The ones that don't melt are above the temperature that the rotor reached telling you how hot the rotor got. This way you know the temperature that the rotor reached even if the rotor has cooled down by the time you can check the temps.

 

[DaveM]

Nice job on the nose duct. You can just direct the hose toward the rotor center, but a duct sealing off most of the rotor center so the air is forced thru the vanes and outward is much better. By the way your other car was a Swift. Like David Bruns racecar or Swift Japanese streetcar?

 

[Sam McDowell]

A 1946 Globe Swift shown with my name. I had it for 25 years till the FAA denied my medical. So I bought a GT40 that has about the same top speed.