RooDucts were developed to get air to the brakes past the choke point of the frame rail and the arc of the wheel and tire. Because of the flat engine configuration on Subarus, the frame rails are pushed out to their limits which leaves no room for a typical brake cooling hose.
RooDucts take the small voids around the frame rail and front sub frame and direct the air past sway bar mounts, brackets and the tie rod from the front of the car into the wheel rim, brakes and wheel bearing where it can dramatically lower the temperature of these components without restricting turning radius.
The following video demonstrates where the RooDuct fits and how easily it attaches to the car.
While directing air via a hose directly to a backing plate mounted duct used to be considered the absolute best way to get air into the brakes, the flooding of fresh air into the confines of the modern wide wheel rim satisfies most RooDuct customers better than those who use a secondary hose!
Porsche feels the same way: installing RS brake ducts onto a non RS
Cutting a group of holes or fashioning a single opening in the backing plate let the brake rotors take in the cooler air and pump it through the vanes as they were designed to do.
Subaru has given us perfect templates to follow when making these holes by just following the ridges bent into the backing plates. Cutting any higher than the ridge indent will not help and may promote rotor cracking.
There are a few things to know and to do to make the ducts work.
To get air to them, you can use the fogs or any opening up front.
I recommend a cheap 3″ dryer hose from Lowes.
It is flexible, smooth inside and stays where you want it.
It goes inside the duct to keep the flow smooth.
Some of the openings in front are oval to fit between the washer bottle and the plastic shield.
I recommend you not use a secondary hose until you’ve tried it without one.
That second hose is tough to get right and sometimes they collapse and stop the air flow.
You just need to get some holes in the backing plate where the opening of the brake rotor bell is.
Subaru has some ridges just in the right spot to trim to.
I’ve used Blair Rotobroach cutters to make holes while the plate is still on the car and they work well enough.
There’ll be some holes to be made in the inner fender plastic.
Where they need to be will be easy to figure out when the ducts get mounted.
Good scissors or tin snips cut the plastic like butter.
The ducts need to be where the tie rod will fit best under the body just in front of the outlet.
Get them up as high and tight to the body as you can to get maximum space for the tie rods.
Some GD’s have a round vibration damper on the tie rod that needs to be removed.
Just unscrewing two 10mm headed bolts will take it off.
The bottom duct mount will line up with the swaybar mount.
Getting fresh air to the brakes will make your pedal stay firmer longer,
reduce rotor cracking and will keep your pads from vaporizing so they’ll last longer.
The ducts won’t cure anything and everything but going with them first will help you
upgrade your brakes in a more structured, cost-effective way.
Depending on how hard the tracks you go to are on brakes, the RooDucts may be enough.
Try them as I recommend first and see how it goes.
To easily see what it would be like without them, just put rags in the inlets and try a couple laps.
It won’t take long.
If the distance between hard braking zones is short at a track, the next step, if your rules allow them, are electric fans that will supply 60MPH air at all times.
The fans have been working great on all the test cars and if legal for where you run, are the absolute best, but more costly, solution.
Even with the fans’ cost, you are still way ahead of buying rotors and pads every weekend or upgrading.
Just the savings from flushing all that burnt fluid adds up fast.
If you put the car on a dyno, you may want to remove the ducts.
Without air flow, the headers may melt the ducts.
On GR’s, an air separator plate between the 02 sensor and the RH duct is a good idea.
Even some gold tape would be good.
Our test car has neither and is fine but I want to mention it.
I’ve gotten reports that on GD’s the up-pipe flange is radiating
too much heat to the RH duct on some cars.
If you can, put a piece of tin or aluminum between the flange and the duct.
Even if it touches the flange, that’s OK.
We just need a little air between that and the plastic.
I got an email from a potential customer that read, ” …I’ve read several posts from owners on nasioc that the abs models can break fairly easily…”
Its hard (some would say, impossible) to argue with people on the internet but all the customers who have broken RooDucts and have contacted me have been satisfied that with proper mounting the damage would not have occurred. The RooDucts are easy to mount but because the duct is made to use all the space available, mounting it in the correct position is critical and can take some time, thought and testing. If the duct is mounted in the wrong place, suspension parts can hit them and cause a crack. I think cracking plastic is preferable to bending a tie rod.
Some glue or tape can effect a repair in the field and I’ve replaced the damaged ducts that I’ve been made aware of with, along with tips on how to keep the same thing from happening again.
Here’s a picture of a broken duct with the cause easily seen. Note how the paint is missing from the hit by the tie rod when in bump.