240z Brake Pad Question

[Tom Donnelly]

Chet's old z, the one that won the ARRC, had 2 ducts on each side of the air dam and 2 ducts attached under the bumper that went through the large center hole in the airdam. Totaling 6 ducts. I have a picture somewhere. The GCR denotes the ducts allowed in the airdam by total size. And the center section isn't really the airdam, its an existing hole. So they (Katman and Chet), had a duct for each of the 3 hoses that ran to the brakes. I don't remember if they ever got protested, or what happened if they did. The airdam ducts didn't go over the total allowed area for the airdam. As I recall. (I could be remembering wrong, and I'll try to find the pics)

Tom

[Tom Donnelly]

Here's one pic. Its hard to see the center ducts but they're there if you look close.
They're under and right by the bumper uprights on each side.

I'll try to find a better pic.

[Tom Donnelly]

Here's John Williams car, only 4 ducts though.

[Tom Donnelly]

Here's my car, although there's room for improvement. I have the clamshell on the rotors and the duct to the caliper. I need to run the 3rd set of ducts for more cooling. No pedal twice at 10 at Road Atlanta a couple of weekends back. The center ducts under the bumper could be bigger. Look back at John's car. My center duct is just to the right of the tow hook under the bumper.

[TomL]

Tom - There is NO limit on the number or size of ducts in the air dam. The only limit that applies is the number of holes you can cut in the front valance, which is basically one hole per side for a 3 inch diameter duct. As long as you don't cut more than one 3" hole in the valance, you can run as many ducts, and as big as you want, if you can figure out where you can run them (other than through the valance).

[Tom Donnelly]

Tom - There is NO limit on the number or size of ducts in the air dam. The only limit that applies is the number of holes you can cut in the front valance, which is basically one hole per side for a 3 inch diameter duct. As long as you don't cut more than one 3" hole in the valance, you can run as many ducts, and as big as you want, if you can figure out where you can run them (other than through the valance).

Tom,

You're right, and that's where I've been heading with this. I even think the hole can be larger than 3 inches, so you can have a duct that tapers down to the 3" hose.

You still have your yellow 200sx?

Tom

Where an air dam/spoiler is used, two total openings may be cut in the front valance to allow the passage of up to a three (3) inch diameter duct leading to each front brake/rotor assembly.
Where no air dam/spoiler is used, two total openings of a maximum size five (5) inches by seven (7) inches maybe cut in the front valance so that brake ducts can be added with a three (3) inch diameter hose leading to each front brake/rotor assembly.
c. No part of the car, except for the exhaust system and

[TomL]

The Nissan has only a single 3 inch duct per side, and they are located in the radiator opening. I have room to run the hose through an existing internal opening, so I don't have to cut anything. My car may be heavy, but it has big vented discs so I can get by with that little brake air. But it's marginal and I'm trying to decide how to run a second duct.

A problem I have with the rule that you cited is that on my car, it is easiest to have the airdam as a "chin" spoiler (i.e., a small strip - 3" tall - of plastic) bolted to the bottom of the stock valance. That leaves me without any real room to install an inlet into the spoiler. I'd like to install a 5x7" duct into the valance, but if I do that I'd have to eliminate the spoiler altogether.

So my options are:
1) chin spoiler and no more ducting
2) a bigger airdam (large enough for a duct) and cut a 3" hole in the valance, or
3) remove the spoiler and install the duct in the valance.

A fourth option, using the chin spoiler and a duct in the valance, wouldn't really allow me any advantages over the other three options. But it's illegal as the rule is now written.

I had a long discussion with Jeremy Thoennes about this, but I couldn't even get him to even understand what I wanted to do (I didn't think it was that hard). Anyway, I never could get any consideration of a change. But then I never sent in a formal request, either.

[Tom Donnelly]

Tom,

What if you fabricated a duct that was 3" wide by 2" tall? That would leave 1/2" top and bottom on the chin spoiler. I fabbed a duct from sheet alumninum that tapered into a 3" circle. I just formed the sheet into a cone shape, rivited it together, and cut the front to match the shape of the hole in the air dam. I worked with paper templates first until I got to a final configuration. I did it because I couldn't find a duct sold that was small enough for the Z car car. I wish I had a decent picture.

If you're at Road Atlanta in July, I'll find you and show you what I did if you want. It cost me like $4.00 per duct.

Tom

[Tom Donnelly]

Tom,

I re-read your post. You mean you can duct the air dam but not the chin spoiler? I hope that's not right.

Tom

[TomL]

I guess I should have been more clear. I am not legally prohibited from putting a duct in the chin spoiler, it's just that if you put even a 2" tall duct in a 3" tall spoiler, the structural integrity goes to pot. First time you run through the grass, you're likely to rip the whole thing apart. I use the "stock car" plastic, which is flexible and will take off road excursions just fine, but only if you don't cut most of it out for a brake duct.

If my front valance were further off the ground and I had room to run a 6+" tall spoiler, I'd put a duct in the spoiler. But I can't. Maybe I should just raise the ride height by 3 inches in the front to solve the problem?

[ITZ34]

Thanks Tom
I've seen pictures of Chet's car before, but didn't think you could legally cut four holes in the airdam.
The other 2 ducts I assume (as shown on John Williams' car) go through a hole you cut in the inner fender. Is that correct?

[ITZ34]

AHA Just ran out and looked at the car. I see where they go now

Thanks

[Tom Donnelly]

I use the "stock car" plastic, which is flexible and will take off road excursions just fine, but only if you don't cut most of it out for a brake duct.

If my front valance were further off the ground and I had room to run a 6+" tall spoiler, I'd put a duct in the spoiler. But I can't. Maybe I should just raise the ride height by 3 inches in the front to solve the problem?

I remember you passing me in the grass on the left just before the esses once. I think you handle off-road excursions just fine.

[pballance]

Hey Tom, If I didn't get the last ones, Pegasus has HT-10's in stock.

[Tom Donnelly]

Ok, thanks Paul. I think you found the brake drums the last time too.

Keep looking!