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I'm looking at adding some ducts to my front brakes, using the fog light holes on my front bar as the inlet (can is an SE).

The Singular Motorsports ones look great, but are also over $300 once shipping is taken into account.

So I'm considering a DIY option, and was wondering if others have done the same. Not trying it mimic the Singular backing plates, just really to pipe some air in and point it at the rotors.

What did you use for the ducting and where did you get it? I imagine it would need to be relatively flexible, able to maintain its shape when bent, and able to withstand a bit of temperature.

Anyone who's done this care to share?

I looked into doing it myself and ended up just buying Trackspeed engineering's 2 inch brake duct kit. Also as this was the only 2 inch kit available.
I found it wasn't worth stuffing around sourcing clamps, hoses and modifying existing backing plates especially when we were buying over $1 USD. Plus you need to weld a cylinder on the back of the factory plate to attached the hose to. I wasn't going to do a dodgy cable tie it near the disc job.
Unfortunately they don't sell these any more and now sell Singular Motorsport ones which cost more. Plus the dollar is no longer your friend.

I have a SE.
I installed the ducts from where the tow hooks are. I cabled tied them here. I put a pool vacuum hose nozzle in the end so the end of hose those did not collapse.
I trimmed the inner guard splash shields where they meet the under tray and sway bar and ran the hoses through there. I cable tied along the sway bar and then into the new ducted brake shields.
On the right side make sure you place the hose well above the intercooler pipe on the way thorough the splash shield. If you go to low the hose sits more outwards and end you end up tearing it to shreds with your tyres at full lock.
Also I went with a 2 inch kit as a compromise because the car is a road car and gets used for motorkhanas as well as track events. Full lock steering happens quite a lot so space was important.

The duct kit came with some sort of heat rated orange flex hose with a wire coil through it. There was enough to the job and had enough for one repair. I have the same stuff at work but it is 4 inches.
I could not find this sort of stuff at a general chain hardware store at the time in a sensible size. Online places had it but wanted ridiculous money for it. Another reason I bought the kit.

I bought some stock ducts to modify and ended up buying some Singular Motorsports from Trackspeed Engineering.

Haven't installed them yet. I still have the spare ducts somewhere if you want some to modify.

I recently installed the Singular 2.5in ducts in the SE (but haven't had a chance to route the piping)
The kit wasn't cheap but when I priced the high temp reinforced ducting pipe locally, the Singular kit price didn't look so bad.

If you do go with the 2.5in or 3in singular kit, the outlet for the hose pushes hard on the ABS sensor. Like really kinks it over and would probably do damage in the long run. I doubt you'd even be able to slip the hose and clamp on to be honest.

After a bit of research I found both front ABS sensors are the same sensor but have different wire mounting brackets for left and right (hence the different part no.) I swapped around the front left and right ABS sensors so the tail from the sensor points down instead of up and it allows much more clearance. You just need to pry open the metal brackets that holds the wire to the car body so they are orientated the correct way.
Pretty quick job to do. Prying open the metal brackets was the hardest part but at least you can do it off the car
Oh and the fun part of locking up the brakes on the grass to activate ABS to make sure it still worked and wasn't going to throw an error.

The mechanic that installed the ducting shields (needed to pull the hubs to install so that went in the too hard basket - pay someone else to do it list) said that he wasn't overly impressed with the quality of the fit. The item itself is made beautifully but he said he had to do a fair bit of bending and straightening as the shield was hitting hard on the rotor when installed. It clears now but its very close. That and the ABS sensor clearance.
Have done 2 track days since and theres no rattles or grinding so it seems all good.

Before:


After:

The kit wasn't cheap but when I priced the high temp reinforced ducting pipe locally, the Singular kit price didn't look so bad.

So I'm not the only one to find this.

Removing the hub on a NA/NB is probably one of the easiest of any car. No puller is required.
Remove the brake calipers and disc first. 14mm bolts.
Remove the hub centre cap.
Undo the 29mm centre nut and the hub literally pulls of by hand with minimal effort.
Remove the existing brake shield, 3 12 mm bolts.
Replace with new shield.
Put hub back on and use toque wrench set to 167-215nm. You are supposed to use a new nut, but I have only replaced mine once after many uses and don't have any issues with it.
Put brakes back on.

I can't remember off the top of my head which way my ABS cables sits, but I gather it is the same as your original configuration.
That clearance for the Singular kit is bad.
I understand why they have done it, so the air is as close to the centre of the hub as possible, but it shouldn't be at the cost of clearance issues with the ABS sensor cables.
The Trackspeed 2 inch kit had room around the tubes for the ABS sensor cable. It was also nowhere near rubbing on the brake rotors.
It required no bending to fit it. It did mention it may need it if it rubs against the disc in the instructions.
Due to heat over time it actually curved back towards the lower and steering ball joints. I have 2 holes in each shield now from rubbing on these which has nil effect on the operation of them as the ball joints seal the hole.

I made up one duct myself but haven't made the mirror for the other side nor had the tube welded on yet. I used a cardboard template, matched the mounting holes on the spindle and then traced the outside radous of the disc.

It's best if you shield the lower ball joint from radiant heat so try and get the template to go between the rotor and the ball joint. You need some horizontal bends in there to achieve that and also gain rigidity so you end up with something sinilar to the Singular shields bit custom to your rotor size.

I don't run abs so I placed the hole closer in to the hub. All up around 15-20 mins making the template and then that again to cut and bend it out of aluminum.

You might want to pay attention to Beavis' build if you really want to DIY your ducts:
http://www.miataturbo.net/build-threads-57/beavis-white-nb-turbo-track-car-87194/page2/

Personally I'd just buy the ready-made, proven ducts rather than invest the time to make them and find out if they hold up to track work.
If you do DIY them, make sure that they're extremely robust and won't tear off - it gets very hot there and the harsh vibrations will eventually crack any load bearing aluminium bends (if you were thinking of using aluminium).

Great stuff, thanks all. I think I will probably just go with the Singular Motorsports option - if you've seen my radiator/intercooler ducting thread you'd know that fabrication is not exactly my strong suit.

In the meantime I might even just try popping out the foglights to get a little bit more airflow in there, after the radiator ducting there really is no air getting in there at all any more.

Next track day on Thursday night

I have 3" Singular ducts on my NB. Although not compared back to back, I can say with certainty that they are super effective. The last track day I did without them was around 24c air temp, 7 lap sessions of the Sprint Circuit at Queensland Raceway. Surface temperature of the rotors was 292c as measured by an infrared thermometer after the session ended. The next time out I had installed the ducts, and did 10 lap sessions of the National circuit (much harder on brakes) in 34c air, and measured the surface temperature at only 232c. A full 60c cooler, in 10c hotter air, on a more brake-heavy track, for 3 extra laps. Very impressed. Significantly reduced pad wear over that weekend when compared to past track days without ducts, too.

The pad wear is what I'm most concerned about. Good to hear they're working well for you. I think I will go with the 2.5" as I'm running the stock undertray and may move to 15x9s down the track.

2.5in flows a lot less air than 3in, if you need ducts you need 3in. 3in is a bit harder to finesse around big wheels and ductwork, but doable. The Singular ducts (3in) on my racecar required some improvisation to achieve fitment, bit no biggie.

3in ducts rock! Brakes rock with 3in ducts!



PS put some mesh in there to stop stones etc getting blown onto disks.

I went through the plans of building the 3inch ducts, but never got around to fitting them as I upgraded to the 11.75" rotors and low wear pads. I really don't have overheating now where I need the ducting, if anything I don't want to increase the time to get them warm. I was thinking of adding a gate in the ducts so on the hillclimbs I run with them closed but on track events I can open them up.

If you spec the right rotors and pads then it's not a major problem. I'm running Ferodo DS1.11 pads which are an endurance, low wear, constant friction pad so they generate a flat friction coefficient curve.