Front braake ducts

Zeke · 07-30-2002, 08:05 PM

Did a search and couldn’t find this: How do you run the ducts for the front brakes? Where can you drill the holes? I have a 916 bumper and I was hoping to use the driving light holes for air inlets. This would have the air duct run just under the headlight bucket and out just in front of the wheel. What kind of clearance is necessary. I ask because at present I have no suspension bolted up. I’m still cutting holes and fabricating. Thanks for any help.

campbellcj · 07-30-2002, 09:38 PM

The last setup I saw up close (an Ottos /6 car) I believe used the Smart-Racing duct kit, which has a swivelling attachment to the A--arms. Here's a link: http://www.smart-racing.com/ProdCat/Brakes/brake_components.htm

The inlets were from brake cooling ducts designed into a deep f/g spoiler - available from Perf Prods and others I think. Obviously with this setup there is not much ground clearance at all with the deep spoiler and the ducting running under the car. This was a dedicated (trailered) race car.

Other than that kind of set up, I'm assuming you'd have to cut holes in the wheel wells and run the ducting thru the trunk.

I was contemplating a set up like described above, but (for now) my car will need to remain somewhat streetable and driven to the track...and I'd hate to hang up an expensive spoiler and cooling setup on road debris or a driveway and tear the @#%! out of the car.

Paul_Heery · Paul_Heery's Garage

Take a look at these from Tangerine Racing.

http://tangerineracing.com/Brakes.htm

John Rogers · 07-31-2002, 06:02 AM

Hi Milt, glad to hear the car is moving along, maybe I'll see you at the track shortly??? Anyways I use openings in the front bumper that go into the front trunk beside the oil cooler and exit the sides right at the brake area. I think the hols are about 5 inches square? This was done by the shop that setup the car years ago and they used some adapters and dryer duct hose from Home Depot and the hose lasts a couple of years before stones start eating through it. There is nothing in the outside wheel area except an extension from the inner fender adapter so there is no tire clearance problems with my slicks and the brakes get a good supply of air. Good luck.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Zeke, are these vented rotors or solid? Solid requires more work at the rotor end of things--ducting to make sure you get a roughly-equal amount of air on both sides of the rotor, so they don't warp into a cone shape. With vented (e.g., 911 or 914-6) rotors you can just duct the air to the center and push it into the air passages...

--DD

Zeke · 07-31-2002, 07:24 PM

Dave, they are vented. I see RacerChris has a sheet metal gizmo that directs the air down through the caliper.

My main concern is the most favorable point of entry into the wheel well. The duct has to be able to move up and down and stay out of the tire's way. Just in front of the strut?

boxstr · 07-31-2002, 07:50 PM

Check out the AJ-USA site for there brake duct kit. Really compact and looks like it will work very well with the 914. Exspensive.. $300.+
I saw this in an article in the San Diego PCA club newsletter.
Craig C. Laughlin CAMP 914

Brad Roberts · 08-01-2002, 08:56 PM

We use the AJ USA setup on 911's and 914's that are not fully pumped race cars. Its attaches to the control arm with a small thin scoop. These work really well directly forcing air into the center of the rotor and out.

The key is: not cutting the tub.

B

Dave at Pelican Parts · Dave at Pelican Parts's Garage

The ones that attach to the A-arm are also legal in Zone 7's "improved" and "production" categories. I don't think body-mounted ducts are. I know they're not in "improved", not so sure about "production".

I might eventually see if I can come up with some similar ducting for solid rotors. It would be nice to have my brakes last the full 20-minute run session. (Actually, the right way to have them last that long is for me to learn how to stay off them for long enough!! I over-brake on track, and do not use all of the brakes when I use them... More tightening of the "loose nut behind the wheel" is needed!)

--DD

Brad Roberts · 08-02-2002, 10:52 AM

We will get you there. We scrub off speed with the tires.. you just need really good tires to do this for a 20 minute race.

The tube car has a 1 inch rear master cylinder and 3/4 inch front master cylinder. The brake pedal is a brick while the car sits in the paddock, but it sure is a confidence builder when it comes to stabbing that pedal going into the first turn from the longest straightaway at over 130mph.

B