DIY brake ducting
 

I'm considering either buying the commercial brake duct kit from C & T Automotive Engineering:

https://www.s2ki.com/forums/showthread.php?...threadid=102928

or rolling my own.

I figured I'd start by planning the do it yourself version, and see what problems I ran into.

Anyone who's already done this, please jump in with suggestions, warnings, pictures, etc.

Here is what I see as the greatly simplified steps:

1) remove front bumper (very easy)
2) cut faux vents with Dremel
3) attach NACA or similar duct (what model?)
4) attach 3" to 2" hose adapter (SPA-D103B $14 each)
5) attach 2" 600

I have checked dimensions of available ducts, and as you mentioned, what is available seems too big. I saw a post of someone who used ducts which looked ok in the bumper; I was not able to tell if ducts were cut down or pushed from behind over the bumper configuration, etc.

While waiting for C&T, I used patio drain inlets which accomodate 3" ducting into the faux ducts. The patio inlets are cut down on opposite corners to fit and the other corners are used to bolt to the faux opening, which was cut in a circular pattern to fit the patio fitting.

2" tubing will take crimping or major turns to fit around or through the air pump apparatus.

Despite heat turning my rotors blue, there was no surface crazing or cracking that I could see and pedal feel is firm; I usually get softer pedals due to bubbles with at least Super Blue. Pads are lasting longer with equal wear inside/outside pads.

I recommend ducting of some sort.

Good luck! I like the C&T; I saw them on sidweways' yesterday at UL's dyno day.

Al,

thanks for the info. I'm eagerly awaiting a firsthand look at the C&T kit, myself.

My estimate is that it will take right around 4' of tubing per side, so one 11' length would be more than sufficient for one car.

Who has done this arelady? Please help us out here.

Thanks again,

Ted

My brake ducting cost about $8 total if you don't count the hole saw.

Used Home Depot flexible 3" dryer ducting routed from in front of the radiator, through holes cut in the front underpanel - cut #1 :( - and then through another hole in the fender liner - cut #2 :(:(. With big front tires there's not a whole lot of room to route stuff, but a few bends and well placed cable ties got the job done.

Made larger the holes in the back side of the rotor dust shields to try and accomodate the air coming out of the ducts. The stock rotors appear to be designed to take air in through these holes, routing it out through the rotor vanes.

Didn't want to permanently modify the front bumper, hence the perhaps-less-than-optimal routing. Looks ugly but worked pretty well.

(ugly brake duct/gratuitous glory shot :o)
https://cimg3.ibsrv.net/gimg/www.s2k...fdde74bed7.jpg

My mechanic cut hole in the plastic leading to the front of the radiator, then used hose clamps to route the tube to the dust shield.
You can argue that it isn't optimal, but it is cheap and works okay.

http://www.nsxfiles.com/images/viken_brake_ducts.jpg

-Doug

jzr,

i've read that the ducts are more effective at catching air
the closer the intakes are to middle of car, so this may be better than opening faux ducts.

Jason,

thanks for the picture and info on the really low-budget BAUBD.


Doug,

thanks for the info and picture; including it here for easier reference:

http://www.nsxfiles.com/images/viken_brake_ducts.jpg

Do you have a photo of the intake, or how the hose is routed?


Will,

interesting thought on intake placement. I wonder how the three locations (faux duct openings in the bumper, Jason's more central locations, C&T down low in front of tires) actually compare? I think for most of us, any thing is better than nothing, so other isssues are probably more important, like ease of construction and hose routing, aesthitics (apparently not that important to Jason ;) )

I'll try to get a photo tomorrow, the car isn't at my house right now. If you are working on your car today, mine is pretty much like Jason's. The front is tie wrapped in front of the radiator (lower than Jason's), and then you cut a round hole in the plastic area to route it back to the brake area.

I think Jason has bigger ducting than me, which is a good thing.

-Doug

Doug,

thanks, no rush. I'm just trying to gather information for people who might do this, and trying to make up my mind between building my own or buying C&T's setup.

I've been considering using an electric blower to push more air to the rotors... Then it doesn't matter as much where the air comes from, just as long as its cool.

Tedster,

bumper intake ducts are supposedly optimally positioned vertically to avoid "skimming" which the narrow C & T ducts could suffer from.....??

It certainly 'feels right' to use the faux ducts for something, but I fear that it will be much harder to route the hose from there than underneath.

You got that right about the difficulty, particularly on the left side, imo. Seems like the shape of the bumper will help deflect air into the faux duct area.

I did mine over a year ago so most of the pics are gone (with photopoint) but I am convinced of the value. I did cut the ducts in the bumper because I don't like the fake look. If I had it to do again I would probably use 2.5" tubing instead of 3" since 225/16 at full turn can sometimes cut the tube. I did find that I liked the look after I installed grills on the openings and pick up fewer leaves and grasshoppers (since I left the vents in the backing plate they would stack up there).

More brake duct pictures

www.nsxfiles.com/images2/brake_duct.jpg

www.nsxfiles.com/images2/brake_duct2.jpg


The hose in the front grill has a metal "flange/lip" at the end of it, with a couple of holes drilled in it, tie wrapped to the grill.

-Doug

Does anyone know just how much air is pushed through the hoses at speeds? If it really ain't blowin hard what is the point.

I think it is important to have a larger opening feeding a smaller hose to get some volume and velocity going... Or use a blower to pull the air in.

Anyone done some testing??

Chris,

Thanks for the info. Did you use a NACA duct or similar, or did you just run the hose to the opened faux duct? I need to clear 235/17 RA-1s; I think I'll be using 2" tubing! If you ever come up with some photos, please post 'em here.


Doug,

thanks for the additional photos. I'm including them here for easy viewing:

http://www.nsxfiles.com/images2/brake_duct.jpg

http://www.nsxfiles.com/images2/brake_duct2.jpg

Here's what Tom Suchocki, Chief Engineer of C & T Automotive Engineering, said about their composite dust shield:
I wonder if DIY brake ducts that aim at one side surface of the rotor are contributing to cracking rotors?


airsport,

I believe that Ultimate Lurker did some testing on the C&T duct kit, showing that it did reduce temperatures, but I can't find that thread right now. There is also anecdotal evidence from people who have done DIY ducts that their pads last longer.

Here are some photos of the C & T kit for comparison. [Phil "Sideways", I hope you don't mind me reposting your pictures here.]

https://cimg6.ibsrv.net/gimg/www.s2k...1690323acd.jpg
https://cimg7.ibsrv.net/gimg/www.s2k...5f9791ef11.jpg
https://cimg8.ibsrv.net/gimg/www.s2k...a7cf5d7ad6.jpg
https://cimg9.ibsrv.net/gimg/www.s2k...a156c0d4b7.jpg
https://cimg0.ibsrv.net/gimg/www.s2k...0c396f0000.jpg

BTW, two site sponsors, Coastal Metals and Grille-Tech, offer grilles for the faux duct openings, and Coastal Metals offers bracket attachments for theirs to allow attaching of hose.

As far as I know, no one is currently selling ducts nozzles, although I believe that Bulletproof Automotive used to sell carbon fibre ones.

Does anyone have any additional info on grilles or ducts/nozzles?

I used some of the original Bulletproof CF ducts (imperfect seconds) that I cut to mate to the 3

Temp reductions are really hard to measure. We used some temp sensitive paint initially and saw some reductions, but its hard to determine what color is what. C&T needs to get some of those stick on indicators that change color when a certain temp is hit.

I'm a firm believer in brake cooling, no matter which approach you take (DIY, C&T or other). There's a reason why virtually every race car out there uses brake cooling. :-) Directing at the rotor eye is definitely preferable, and it would seem you could get some uneven cooling if you don't. I don't know how big the differential would have to be to generate cracking, and whether or not the DIY setups would create that differential.

On the airflow, we ran the tubing from the duct up into the cockpit of my car to see how much air (anecdotally) we were moving. It was quite a bit even at 30-40 mph. No way to measure it precisely. The front in-bumper ducts are better placed for airflow, but I prefer to use one of those for the CAI.

UL

After 3" ducting used, my brakes have worked better than they ever have with even wear between inside and outside pads.

The hoses are generally directed to the hub area with 1/3 of the hose pointed to the rotor surface. I notice Hayashi's seem to be mostly toward the friction surface, and I havn't heard any problems there.

And as UL stated "It is also considered mandatory to run air ducts to the eye (center) of the rotor on any car used on track or in actual competition." as noted in an article about rotor seasoning.
<Rotor seasoning link.>

Chris,

thanks for the additional photo and thoughts. I really think 2" tubing will carry plenty of air, but it would be good to hear confirmation.


Shawn,

are you saying that you felt plenty of airflow with the C&T tire-spat ducts and 2" tubing? That would be great to know. Thanks.


Al,

more good feedback that ducting is worthwhile!


Harry,

great photos and details of your install. Those are very helpful! Especially good to know that the smallest NACA duct works well if flanges are cut down. Do you have a grille on there now? If not, do you wind up with a lot of debris in your brakes? Any thoughts or photos of routing hose through the driver's side bumper area?


Thanks everyone!

Ted

I have been looking at these DIY brake duct threads for a while and I'm ready to do the fronts, but I'm still not sure how to handle the rears. Any ideas/suggestions there?

I've actually noticed I have more heat problems with the rear brakes.

I don't want to use the faux ducts for this and I'm convinced that with my car as low as it is, I will break the C&T ducts. So I think I want to just get some naca ducts and mount them to the rubberized plastic pieces under the bumper. I figure if I mount them flush, they wont get much air, but if I angle them slightly, they should be fine. I'll use 2" tubing and route it to the eye of the front rotor.

But on the rear, I think I have no choice but to point the air at the inside surface of the rotor. And I have no clue where I should draw the air from.

Hi Ted, yes, there was quite a bit of air with the tire spat ducts and 2" hosing.

Rev, does your car scrape the stock spats? The C&T's have a little more clearance (maybe a half inch?). They also withstand abuse pretty nicely, as I've nailed one a couple of times not paying attention. I'd go for the fiberglass versions if you fear contact, as they are cheaper, easier to fix, and perhaps a bit more flexible.

UL

p.s. - They're really easy to install/remove at the track too. Takes all of 5 minutes a side and then just tuck the tubing away. Brake ducting on the street is pretty useless for all but the criminally insane :-) Oh wait, I leave mine on for the street.....

Rear brake overheating is another interesting issue.

Some have stated that the rear brakes should only overheat if the fronts are losing stopping power for some reason, and the brake bias is moving towards the rear. Others have seen heat problems in the rear, but aren't aware of any issues with the fronts at that time.

Who knows?

I scrape the front strakes pretty regularly, so I think I would destroy the C&T ducts inside of a week. I manage never to scrape the bumper, but the strakes scrape regularly and once in a while I slightly scrape the exhaust tips (although it's barely enough to even scratch them).

There have been a couple of times I've seen my rear brakes overheat (smoking, etc.). Once was on a mountain drive when I pulled off the road after a hard stop from 140 ish mph. I figure they were probably already plenty hot from mountain driving and then the stop from 140 to 0 probably was the kicker there. Also, I notice at the track that the rears seem to get pretty hot... but then again, I basically melted my fronts at the last track day, so Ted's theory that the rears overheat when the fronts stop working isn't a bad theory.

I can't find Naca ducts for 2" hose. Everything is for 3"...

What's the consensus on the best size hose to use? 2"? 3"?

Do I really need to use ducts, or can I just route the hose under the car and point it forward?

I'm thinking on the rears maybe it would be best to point the hose at the caliper instead of cutting the heat shield and pointing the hose at the inner surface of the rotor. Any thoughts on this? Might lead to less overall cooling, but there's a lot of surface area on the caliper and if I point the hose there, it will still get some air to the pads and the rotor. Thoughts? Really, it just seems easiest to me...

I'll chime in later on ducting, but I'll say a few things from what I've experience on the track.

the rear rotors heat up approximately 150-170 degrees hotter than the fronts. remember they are not vented rotors, so they do retain as much heat, and fail to dissipate as quickly than the fronts. even though some might think that if the fronts are overworked the rears will heat up - well, the rears have zero chance of getting ventilation without some user input like hecash or C&T's modifications.

the fronts, even though you aren't getting full blown air going into the faux ducts, this might work better, because I do not believe you'll need 90mph winds into the brakes, so some can pass right over the faux ducts. but that's just my take.

Hecash,

Very nice setup. I've got it on my to-do list.

I show the first racerpartswholesale NACA duct as part #SPA-D100, $15.99, 4"x8.5" opening. Does this sound right?

And #THE-SS300, 11' three inch silicon ducting, $64.99.

Also, have you had any problems with your powder coated calipers melting? Much of the powder coating on mine has discolored or dripped away from track heat. It's been much better after removing the dust shields, which will likely go back on when I have ducted cooling.

Rev, I think if you want to go 2-1/2" or 2", you buy the 3" NACA duct thn use the hose adaptors, #SPA-D103A or SPA-D103B $13.99 which snap on to the ducts.

I've boiled my superblue on track numerous times, so pfb advised me to remove all of my dust shields as a way to help keep the temps down. Before I do, though, can I get some other opinions on the effects of removing them without running duct?

I see in the pics that everyone still has their dust shields on, and the C&T kit has some too. I'd like to avoid the expense/effort involved with ducting if I can. So, are there any real disadvantages to removing the dust shields?

I think something else must be wrong if you are having heat problems with the rear brakes. I had problems with the rear rotors once at the track (wore through rear pads in a weekend), but maybe the parking brake was kinked, or something is warped, or the pins not lubed. In any event, after I replaced the pads, now they last 3-4 times as long as my front pads.

-Doug
Not claiming to be brake engineer. Or a mechanic!

[QUOTE]Originally posted by Doug Hayashi
[B]

I think something else must be wrong if you are having heat problems with the rear brakes.

I got lazy and left R4S pads on the rear while using P+ on the front for a full track weekend. It seemed the braking was not as effective the second day but I didn't see the reason until I pulled the rear pads. They crumbled in the middle and were destroyed by the heat, a little tough to see in the pic below. I now use the same compound front and rear on the track (#3, P+, whatever) and have pretty equal wear with no heat problems.

https://cimg0.ibsrv.net/gimg/www.s2k...5ae7f7cdb1.jpg

have someone take heat measurements in the hot pits or else when you pull back into the paddock. you'd be surprised how much hotter they get. true, the pads back there last longer, but they heat up considerably. if I could, I'd adjust the brake bias slightly - a 1/10th of a turn to the rear. but I'm doubtful that a prop valve can be used on this car.

I had the same desire as you. I recently switched to Cobalt Friction for my braking needs and asked Andie to recommend something to give me a little more bias. He suggested running Ferodo DS3000s up front and the Cobalt IT-C pads in the rear. It definitely moved the bias toward the rear and I'm pretty pleased.

I think any good brake manufacturer could give you a good recommendation on mixing pad materials to move the bias around without having to worry about proportioning valves.

UL

[QUOTE]Originally posted by Schatten
[B]
if I could, I'd adjust the brake bias slightly - a 1/10th of a turn to the rear.

I use R4S front and P+ rear. I wanted to dial out some of the nose diving I was getting from my worn out shocks. I am going to try HT-10 rears with Pagids up front next.

[QUOTE]Originally posted by Schatten
[B] if I could, I'd adjust the brake bias slightly - a 1/10th of a turn to the rear.

[QUOTE]Originally posted by ultimate lurker
[B]I had the same desire as you.

[QUOTE]Originally posted by hecash
[B]cdelena,
I recall that you wrote in some earlier thread about the Porterfields disintegrating on you and at that time I failed to take you seriously enough.

I've had R4S's completely disintegrate (worse than the pictures) from street driving... Granted, it was almost a 200-mile mountain drive, but it was still street driving.

A couple of comments:

- If fluid boiling is a problem, try Castrol SRF. It appears to be expensive but due to its high wet boiling point I have found that it lasts at least one year and never requires bleeding, so it is in fact quite cheap compared to pad, tire and gas expenses.

- Removing the dust shields does not increase cooling significantly. You will still need to replace pads and rotors and service the piston seals about as often as you did before.

- Same goes for the 2" C&T duct system. If you are hard on brakes it does not improve the situation significantly. The inlet scoops are also exposed to damage. One track off or an unexpected driveway bump will strip them off the car.

see below.:eek3:

i found these electric blower fans that fit inline for 3" ducting for brake cooling. Are these of significant use? i.e. do you think they would be needed or yield real benefit to the S2000 or are 3" passive ducts as much as you need? anyone have any experience with these. i think i'll get some.

[QUOTE]Originally posted by sfphinkterMC
[B]i found these electric blower fans that fit inline for 3" ducting for brake cooling. Are these of significant use? i.e. do you think they would be needed or yield real benefit to the S2000 or are 3" passive ducts as much as you need? anyone have any experience with these.

the race shop i was at says they really blow hard, he carries all the other ducts and tubes shown above....used for some late model stock cars, short ovals i presume. any websites carry these? i was under the assumption this would force more air than simple passive ducts and tubes??

[QUOTE]Originally posted by sfphinkterMC
[B]the race shop i was at says they really blow hard, he carries all the other ducts and tubes shown above....used for some late model stock cars, short ovals i presume. any websites carry these?

Might not be a bad idea (fans). The only time I've gotten fluid fade is if I don't cool the brakes enough before pitting (say, if I came in before the checkered w/o a cool down lap).

UL

they are basically hairdryers w/o heating element

Stick your hand out the window when you are going 50 mph and feel the wind pressure. Your hand is probably about the same size as the brake duct cutouts. Now imagine what kind of fan you might need to produce that same force...

The pressure is not additive; The fan won't take that force and add "just a bit more" to it. In fact, it is likely to impede the flow somewhat at higher speeds.

Harry,

No URL, saw them at Hi Tech racing in Van Nuys, but i will see about what catlalog or website has them.

PFB,

i agree they could impede, i think you might need the dual intake NACA duct, one open, other with blower and then merge to
rotor outlet. have it switched, and flick it on when you encounter unexpected slow go after hard braking(ie red flag, lack of sufficient cool down lap, hot pit for anything, black flag, or extremely brake intensive track...? hillclimb, etc.)

I just ordered some 2-1/2" silicone duct hose which I plan on routing to the faux air ducts, which I will cover with little Grille-tech grills. How should I secure the hose end to the duct opening?

Should I try to fashion some sort of hose nipple onto the backside of the grill? What about simply using a hose clamp and wire ties or twist ties?

I'm trying to figure out how I should attach my 2.5" hose to the back of the heat shield... Also, what did you guys use to tie the hose to the car? Just zip ties? I was thinking mebbe I should put hose clamps on the hose and then zip ties to the hose clamps for a more reliable connection??? Ideas?

[QUOTE]Originally posted by monkeymaker
[B]I just ordered some 2-1/2" silicone duct hose which I plan on routing to the faux air ducts, which I will cover with little Grille-tech grills.

[QUOTE]Originally posted by The Reverend
[B]I'm trying to figure out how I should attach my 2.5" hose to the back of the heat shield...

Just a suggestion. A couple of rivets would do the job quite nicely and be far less work

Yeah, but it will be just two little tiny drops of welding. I don't feel like drilling the heat shields and who know how close the bolts would be to the rotors...

Hmmm - I hadn't even thought about using rivets. I wonder if I can find a 2.5" flange ready-made that I can rivet to the dust shield? I might also use some sheet metal to fab a sorta sloppy/makeshift funnel to direct the air right at the holes in the shield.

I was thinking that 2-1/2" hose would allow enough airflow to get the job done, as well as be durable enough. The smaller hose diameter might also make routing easier. Another thing is that my AEM CAI filter has to share the air with the duct so smaller diameter is a plus there as well. :)

Unless someone convinces me otherwise...
I'm about to buy some aluminum flashing and cut out a pattern that can be folded and soldered into a hose nipple with mounting ears, which I plan on riveting into 3/16" holes I'll drill on the heat shield. Then I'll fit the hose over the nipple and secure it with a #36 worm-gear clamp.

As for the bumper connection, I'll be shaping another nipple that will bolt onto the side grill through 2 screw holes in the plastic faux duct covers. I'll just have to be careful to leave enough of the factory plastic on the bumper to hold the stuff together without tearing off. I'll connect the hose to the nipple just like on the wheel end.

While I'm at it, I'm also going to cut & bend some flashing into a scoop to be bolted onto the underside of the plastic undercarriage to deflect air up through a hole I'll cut right under the intake filter on the passenger side. I might also make a similar deflector to mount vertically around the hole I'll cut in the plastic shroud that separates the wheel well from the radiator. That way some air will also be deflected from the front of the center grill into the intake filter. It'll have to be small though, to prevent significant amounts of airflow being diverted from the radiator.

To top off all this anal ghetto-engineering, :freak1: I'll be painting all the flashing with heat resistant black spraypaint in an effort to make it all less visible as well as to protect the hose from heat on the wheel side and the air filter on the radiator side. :D

[QUOTE]Originally posted by The Reverend
[B]Hmmm - I hadn't even thought about using rivets.

[QUOTE]Originally posted by spider
[B]

Yeah, but it will be just two little tiny drops of welding.

Very interesting approaches to cooling the brakes . Here are a few facts :

2

While I see the front dust shields as being of only minimal importance because they really only need to shield heat from the ball joints and steering boots, the rears are another matter. You really don't want to let much heat radiate to your outter cv - unless you plan to replace the cv boot and rebuild the joint ever few months.

I see no problem with either . The heat radiating from a rotor face travels in a straight line , perpendicular to the rotor face . The boot and CV joint are not in this line of sight . Because of the lower temperature of the center part of the hub this area will have less radiation . If you are really worried about the CV joint and boot , cut the dust shield so the face of the rotor is no longer covered only.


Brad

If my S2000 was a dedicated track car, I see no problem with removing the dust shields.

However, much less than 1% of my car's use is on the track, the only time that the brakes get hot enough to worry about. So the concerns of the >99% use gain some importance. Like keeping dust, debris and water out of the braking pieces. I'm not convinced yet that these issues can be safely ignored.

The dust shield is designed to keep the brake dust off your wheels . Water is not sealed from your brakes or brake parts by this piece of metal . Water and most any thing can go through the open spokes of the wheel . I am sure that some thing might flip up off the road and be deflected by the dust shield , but most of these objects would just bounce off the brake rotor . The only item it does protect is the steering arm boot from the radiant heat coming off the rotor face . This area is easy to protect , while still removing the shield to allow brakes better cooling.


Brad

[QUOTE]Originally posted by dwb1
[B]The dust shield

The dust shield creates a negative pressure behind wheel drawing air through the wheel , pulling brake dust in that direction . If you look it does not protect many rotating parts. The slits in the front of the shield do try to move some air through the rotor center . You will find much more air moving through the rotor with this shield removed , also it allows both rotor faces to run the same temperature . The inside rotor face temperature will match the outside with shield removed.

Brad

With the help of this thread, I was able to put together my homemade brake ducts. Well, almost...
https://cimg1.ibsrv.net/gimg/www.s2k...f567bb8475.jpg
The air pump bracket was bent forward about an inch to make room for the 2.5" brake duct hose.
https://cimg2.ibsrv.net/gimg/www.s2k...382e7dcad4.jpg
https://cimg3.ibsrv.net/gimg/www.s2k...6f6b14a0e1.jpg
https://cimg4.ibsrv.net/gimg/www.s2k...8d5a3f59cc.jpg
https://cimg5.ibsrv.net/gimg/www.s2k...d9c5bc418b.jpg
https://cimg6.ibsrv.net/gimg/www.s2k...a8e721ed95.jpg
https://cimg7.ibsrv.net/gimg/www.s2k...5ad70c05fb.jpg

Where'd you get those nifty flanges from? I made some over the weekend, but yours are prettier.

Also, what kind of rivets are you using? The rivets I have have one side that's all nice and finished, but on the other side, it looks like a little bulging terd thing that sticks out like 1/8". Where can I get rivets that flare out on the other side and sit flush?

[QUOTE]Originally posted by The Reverend
[B]Where'd you get those nifty flanges from?

Spider,
How much weight did you add?

[QUOTE]Originally posted by Sideways
[B]Spider,

Spider,

when you get the hosing routing finalized, can you please post pics. i am having a probleming with my stock tires rubbing at a full turn. when i put my race ones on, it will be worse. i know at the track, you will not be fully cranked unless your in trouble, but i keep forgetting on the streets.

simpson

I didn't have time to pull my bumper this weekend and check, but you think there's any room at all to route ducting from the faux ducts without interfering with my AEM CAI?