Contour Enthusiasts Group Archives Forums Modifications Brakes Front Brake Cooling Deflectors

Okay, so I'm at the auto show two or three years ago and I'm looking under most of the cars to see what's going on in the suspension department, as I usually do. I come to the Porsche section and what do I see, but spiffin' plastic air deflectors mounted to the control arms! ...Along with a couple of inverted NACA duct-type things molded into the underside of the front valance. Anyway, I thought that it would be pretty easy to duplicate at least the control arm air deflector portion of the set-up, so I did!

In thinking about what materials to use, I came up with the idea of using flexible plastic mud flaps. Simple, cheap, readily available, and durable. As I already had some small plastic mud flaps that I was going to put on my Escort, I decided divert them for use with this project instead.

Then I got some square 1/2" OD, 1/16" wall thickness square steel tubing and cut it into ten or so ~1/2" long sections. I only ended up using eight of them (four per side) but I wasn't sure how many I'd need at the time. I then cut one side of the tube off, as close to the curved corners as I could. This made ten little U-shaped pieces. I then got some stainless steel allen socket head screws and drilled and tapped a hole in the side of each U-shaped piece, thereby making 10 U-clamps to hold the air deflector onto the control arm. Then I put some good coats of black paint on the U-clamps.

Next, I cut some rectangular holes in the plastic piece where the clamps would fit through. I was originally going to clamp a piece of steel strap (visible in the third picture) between the clamps and the plastic to distribute the stress better, but it wouldn't fit in the brackets with everything else. I was going to make larger brackets, but in the interest of getting these things put on, I decided to try it without them. I test-fit things on a control arm I had gotten from a junkyard for bushing replacement research. (Still not done with that project...) I also held the plastic pieces to the car and checked for clearance between things. I ended up cutting a little bit off of the top end (if it were installed as a mud flap) as I recall.

Anyway, when I was satisfied with the way things looked and fit, I bolted everything up onto the car's control arms. I installed the clamps so they screwed against the control arm from the rear of the front flange, and clamped the plastic to the control arm.

They've been on the car since June of 2003, and haven't broken off yet, so apparently the steel strap was not necessary after all. They do scrape from time to time (and it sounds pretty bad! ), and have worn off a little bit (yikes -- looks like about an inch! I hadn't compared pictures before!) at the bottom. Also, they would hit on the wheel weights on the rear of my stock wheels when turned full-lock. (You can see the scrape marks from that on the curved portion.) Other than that, they're doing well!

I went to a track day last year with them, and I seemed to have less brake fade than previous times. Unfortunately, I had also changed brake pads, so I don't know how valid the comparison is. Anyway, it's a cheap mod, and it certainly can't hurt to have more air going past the rotors. With the stock wheels, I could see dirt/water tracks that looked like they were caused by air coming outward through the wheel, so it would appear that they actually do move some air.

Anyway, there ya go! Go make your brakes happy!

Finished clamps.


Test-fit on spare control arm.


All the parts ready to go!


Passenger side installed!


Driver's side installed!


Driver's side after 21 months of use.



Marty

(I should have gotten this photobucket account a long time ago! )

kind of a cool idea, ever had any problems with them scraping on stuff like speedbumps or anything?


like the new rubber on them tires

Very neat idea!

Any difference with brake feel when driving in the rain?

Neat mod and great idea, but now let's recite together... d-r-a-g... d-r-a-g... d-r-a-g...

great work GrooveNerd, I like it. Granted, you'd need to do some real scientific-like testing to see if it was worthwhile or not . . .

and durateX, stuff like that under the car doesn't necessarily affect drag the way you think it does. It may actually reduce over all drag (but, it might not) The point being is under the car, you can't make a blanket statement like that; it would have to be tested to know for sure.

Thanks for the comments, everyone!

Yes, they do scrape from time-to-time -- big dips in the road, gravel driveways, too-diagonally-taken speed bumps, etc. I think I've worn off about an inch from the bottom in the ~1.75 years that they've been on.

Yes, in the rain, they apparently work quite well! Either I haven't actually driven on the highway in a really bad rain since I put them on, or it's been a long time and I've forgotten. Either way, a couple of weeks ago, I took a trip on the interstate in a really hard rain. Much to my surprise, I had pretty much zero braking effect for one to two seconds after pressing fairly hard on the brake pedal! It must have been the rain/road spray, because they're not anything like that in the dry -- even when it's cool out! I'm using the precursor to the Bendix Titanium Metallic pads, BTW.

As for the drag issue, lower air pressure under the vehicle means that the obstructions that follow will have less effctive wind resistance. In theory, by sweeping some of the air out from under the vehicle, it will reduce the effects of drag on objects downstream. Plus, the whole idea of air dams, chin splitters and side-skirts is to reduce the amount of air that gets under the vehicle, thereby creating a low-pressure zone and helping to "suck" the vehicle towards the ground. I doubt that these do much to reduce downstream pressure, but as long as they cool the brakes, I'll be happy! Besides, if the drag penalty outweighed the brake cooling benefit, Porsche wouldn't have done it! (Yes, yes, they have engineers, CAD, blah, blah, blah. Come on -- humor me here! )

I'll try to borrow an IR temp gauge sometime, drive with only one of them on, and do some temp comparisons to get some hard data on their effectiveness in the dry.

Marty

Hate to sound stupid or anything, but what exatcly do these do and what would the benifits be, espicially if reserached and everything?

~Alex

They direct airflow toward the front brakes to improve brake cooling. Unless you are doing a lot of hard driving with hard braking at high speeds, you probably would not be able to tell the difference.

Nicely done. Now if they only retracted in the rain.

I need. My brakes were almost on fire when I took a trip to the tail of the dragon. I'll try to get pics of the smoke pouring off next time I go.