Brake Ducts ... are these legal

"Air ducts may be fitted to the brakes, provided that they extend in a forward direction only, and that no changes are made in the body/structure for their use."

Is some thing along the lines of this legal (no, that is not an IT cars suspension :018:)

http://www.hrpworld.com/client_image...21_hdr_2_l.jpg
http://www.hrpworld.com/client_image...cts/1421_1.jpg

rules say air ducts may be added, so I am assuming this would pass as an air duct?

if that is legal, then what about the "in the forward direction only" part. Lets say the top left picture is the front passenger side and has a hose going around the suspension to the front of the vehicle, would that then be an illegal setup due to it not facing forward?

Legal. The facing forward refers to the actual duct on the front of the car that collects the air.

Just remember, that you need to run air to both the rotor and the caliper. The examples that you show only cool the rotor.

Hey Tim - please show a product that cools the caliper - haven't seen examples of that.

Thanks,

I believe he is referring to something like this


http://members.aol.com/wabbitracing/...ake%20duct.jpg


Cooling where the brake fluid is sitting in the caliper, so it doesn't boil.

I think with vented rotors if you cool through the veins you will be accomplishing both at the same time. With the rotors and pads staying cooler you will get less heat soak through the caliper, so indirectly achieving the same thing.

I wonder about tapping the caliper for screws - this is the first version of caliper cooling I've seen and I like the idea however this doesn't appear to have been adopted by many folks - perhaps because of vented rotors doing the job as you describe.

From an engineering point of view. If the rotor is cooler with the ducts, then the brake pads are cooler in effect, which means less heat is transfered to the caliper itself and avoids boiling the brake fluid.

Quote:

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Originally Posted by benspeed

I wonder about tapping the caliper for screws - this is the first version of caliper cooling I've seen and I like the idea however this doesn't appear to have been adopted by many folks - perhaps because of vented rotors doing the job as you describe.

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You don't drive a Datsun :D

Take a look at the ducting i found on my car when I bought it.

http://picasaweb.google.com/ITSa240/Zbrakes

Katman and others have used variations of this same type of setup.

Maybe it will help give you some ideas.

Quote:

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Originally Posted by pballance

You don't drive a Datsun :D

Take a look at the ducting i found on my car when I bought it.

http://picasaweb.google.com/ITSa240/Zbrakes

Katman and others have used variations of this same type of setup.

Maybe it will help give you some ideas.

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My first thought was that it looked very clever and sophisticated, but ... I think it's fundamentally flawed. Cooling works because there is airflow ... cold air comes in and warm air is exhausted to somewhere else. But neither the rotor cooling system nor the caliper system have any easy way for the hot air to escape. I can't believe it's all that effective.

There is plenty of airflow. What you can't see is the opening between the caliper duct and the hose. Of course, having to run solid discs doesn't help either. :(

I haven't measured the temps but before I re-did everything I had smoking brakes on the passenger side and non smoking on the drivers side after a 20 minutes session at a track day.

EDIT, forgot to add the drivers side ducts were hooked up and the passenger side had been removed.

Gotta commend some clever engineering to help the underbraked Datsun

I agree that caliper cooling is more important on solid rotor setups. The vented rotor by design creates airflow to the caliper - albiet not to the specific area that houses the fluid - but conductive heat transfer will stilll allow that cooling air to help reduce fluid temps.

Quote:

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Originally Posted by JoshS

My first thought was that it looked very clever and sophisticated, but ... I think it's fundamentally flawed. Cooling works because there is airflow ... cold air comes in and warm air is exhausted to somewhere else. But neither the rotor cooling system nor the caliper system have any easy way for the hot air to escape. I can't believe it's all that effective.

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It works, trust me. But you fellows with all those vented discs and modern designs wouldn't know about this old school tech now would you? :p And for good reason - you don't have to, which is the way it should be! Wish I didn't know about it.

Most old school S cars have fairly serious ducts to allow them to complete a 30 min sprint and even then it is sometimes marginal. I have a "can" that wraps around the front and back rotor and the air can escape through about a 0.100" gap between the can and the rotor. I also have a duct pointing at the back side of the caliper that sort of wraps around. Both do the job, they allow the brakes to last even in longer races that without the ducting would toast them throughly.

***But you fellows with all those vented discs and modern designs wouldn't know about this old school tech now would you? :p And for good reason - you don't have to, which is the way it should be! Wish I didn't know about it.***

Ron, you need to look at some of the vented disc modern design as you call the later brakes. Look at a few FAST production cars.

How come no one is talking about keeping heat from transfering to the brake fluid other than air ducts?:cool:

Cause you told me my shims and heat sinks were illegal??? lol....

pballance, that was circa 1993-1994. That was group 9 at the apex of turn 11 @ Laguna Seca. The 4 leading ITS cars just passed me going into turn 10.

Group 9 at that time was ITS and ITB. We had on average 50 cars in that group.

Tim,

I can't believe this. I contacted the SF archivist when I bought my car. It is the #66 in the photo. I also watched some of your video on your web page. The race was June 18, 1994 and Michael Scott entered and drove the car as reflected by the logbook.

Dang, what a small world. Thanks for the additional info. I enjoyed looking at your videos on your web page. Dang if the 29 doesn't look like my car but I know it isn't since there are no checkerboard.

Paul

Edit: If you find any video of 66, let me know. It is still alive and kicking in Sediv!!