hunter47
hunter47 Reader
1/15/22 9:17 p.m.

To keep it short: 

I went to try to install the Audi RS3 brake ducts on my WRX because the control arm geometry looked similar - I failed to realize that the Subaru FSB connects to the front of the control arm, whereas the Audi FSB mounts to the strut. I'm planning on zipping off the interference section with a dremel, but I'm worried about the single zip tie being the only mounting point. 

I planned on using some perforated metal strips to try and tie the duct in more than one place, but as soon as I turn the FSB will destroy that solution. So... Would I be safe with one zip tie, or should I try and come up with new mounting solutions? Please keep in mind that I do not have regular free access to a 2 post lift, so I'll need to come up with multiple solutions to try at once. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
1/16/22 9:30 a.m.

I have always wondered if a mounting ear could be piggybacked off of the strut bolts to attach the stabilizer bar to the struts.  This would also increase the bar's wheel rate without needing a heavier bar.

andy_b
andy_b New Reader
1/16/22 9:31 a.m.

Would a combination of trimming and heating/bending to reshape allow you more support while gaining the clearance you need?  Otherwise cutting and plastic welding support back in to secure it may work 

I doubt one zip tie on the end of the duct will be enough support to win the battle against wind resistance. 

hunter47
hunter47 Reader
1/16/22 11:39 a.m.

In reply to andy_b :

Yeah, I'm thinking of maybe making a tab on the duct to also mount to the endlink mounting tab. 

RX8driver
RX8driver Reader
1/17/22 8:59 a.m.

I managed to fab up some brake ducts for my 2015 quite inexpensively. I used some Corvette C6 Z06 ducts to get past the wheels and modified them using some hardware store 4" to 3" plastic duct adapters to get the 3" connections needed for flexible brake ducting at each end. I secured them using the provided mounting tab to a conveniently located wheel well liner fastener. I used those plastic adapters for an intake in the fog light hole (base model, no fog lights) and swap out the stock blanked off covers when I don't need brake ducting. For the wheel side, I took some 3" furnace duct pieces, cut a hole in the heat shield and riveted them in at a favorable angle to get the air to the middle of the rotor. Add some 3" ducting on each end, some hose clamps and you're done. At stock ride height and stock size tires it only rubs at like 98-100% lock, so easily avoidable.

It's not the prettiest, but it was inexpensive and not that hard to do really.

Streetwiseguy
Streetwiseguy MegaDork
1/17/22 9:24 a.m.

Factory Sway Bar?

Took me a couple of days.

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
1/17/22 9:25 a.m.

That's an unfortunate suspension arrangement for running this kind of "deflector" duct, one option might be cutting a rectangular slot in the duct for mounting it to the sway bar link tab on the lower control arm, with the flat mounting flange part against the underside of the LCA. So you'd disconnect the sway bar link, push the duct on, add some zip ties to tighten it against the LCA, and then put the sway bar link back on. You could then trim the inside part of the duct to make room for the sway bar if necessary.

 

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
1/17/22 9:26 a.m.
Streetwiseguy said:

Factory Sway Bar?

Took me a couple of days.

Front sway bar, I was thinking front strut brace at first.

kevinatfms
kevinatfms GRM+ Memberand HalfDork
1/17/22 9:51 a.m.

Would you be able to move it further inward? attach to the fatter portion of the control arm? You could then add some lexan to where you want to deflect more air and it would help clear the sway bar.

PS, remove your backing plates. Duct wont do crap if the air hits another large metal deflector in front of the brake rotor.

 

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
1/17/22 10:06 a.m.

^Or at least cut out a section between the LCA balljoint and the tie rod, this will let air into the center of the disc from the duct while keeping your rod ends etc. from being cooked by brake disc heat.

hunter47
hunter47 Reader
1/17/22 1:13 p.m.

So the sway bar would sit like this in front of the scoop? That might work really well. Sorry for the crude picture. The other plan was to fab up a tab with 90* aluminum angle stock so the rear of hte duct would mount to the endlink tab.

And yes, I had planned on taking my rotor dust shield off, but because the ducts didn't fit, I didn't want to take the time to take them off. If the ducts fit, I'll take the shields off. Otherwise they'll stay on. The shields also have a small cutout in them where the scoops would be blowing air, obviously it would be much better if I cut it out completely but it's not as if there is no air flow going to the rotor.

hunter47
hunter47 Reader
1/17/22 1:17 p.m.
kevinatfms said:

Would you be able to move it further inward? attach to the fatter portion of the control arm? You could then add some lexan to where you want to deflect more air and it would help clear the sway bar.

PS, remove your backing plates. Duct wont do crap if the air hits another large metal deflector in front of the brake rotor.

 

The issue I have with this method is that most of the redirected air would just hit the endlink mounting tab, instead of going to the rotor like I'd want. 
 

this is how I'd imagine it:

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
1/17/22 1:24 p.m.
hunter47 said:

So the sway bar would sit like this in front of the scoop? That might work really well. Sorry for the crude picture. The other plan was to fab up a tab with 90* aluminum angle stock so the rear of hte duct would mount to the endlink tab.

And yes, I had planned on taking my rotor dust shield off, but because the ducts didn't fit, I didn't want to take the time to take them off. If the ducts fit, I'll take the shields off. Otherwise they'll stay on. The shields also have a small cutout in them where the scoops would be blowing air, obviously it would be much better if I cut it out completely but it's not as if there is no air flow going to the rotor.

Yeah something like that is what I was thinking.

hunter47
hunter47 Reader
1/17/22 1:27 p.m.

In reply to GameboyRMH :

I do like this idea. If I slotted the duct as well, I wouldn't even need to remove the endlink. I'd probably want to slot it to make some clearance for the endlink and FSB (Front sway bar, LOL), anyways. I'll try it out! If not, these were relatively inexpensive and was really just more of a fun project. Boomba Racing makes similar CNC aluminum scoops that mount to the control arm with hardware and are actually made for the car. Worst case scenario I buy those. I just didn't want them because they were twice the price and the scoops were small. 

kevinatfms
kevinatfms GRM+ Memberand HalfDork
1/18/22 7:31 a.m.
hunter47 said:
kevinatfms said:

Would you be able to move it further inward? attach to the fatter portion of the control arm? You could then add some lexan to where you want to deflect more air and it would help clear the sway bar.

PS, remove your backing plates. Duct wont do crap if the air hits another large metal deflector in front of the brake rotor.

 

The issue I have with this method is that most of the redirected air would just hit the endlink mounting tab, instead of going to the rotor like I'd want. 
 

this is how I'd imagine it:

Pretty sure its going to deflect a ton of air around that end link and still make most of it to the brake rotor...

The end link will be an obstruction but i dont think enough of an obstruction to not run the ducts.

hunter47
hunter47 Reader
1/18/22 11:07 a.m.

In reply to kevinatfms :

Yeah, I suppose you're right! I'll try it that way first, because it requires no cutting. 

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
1/19/22 10:55 a.m.

So I went looking to buy a pair of these ducts, to fit them to my AE92's front LCAs much like the pic below and perhaps expecting them to have a price in the same ballpark as GT3 ducts, but the cheapest I've found them online so far is over $62US/pair, is there any way to get these cheaper other than trying to find them in a junkyard?

Edit: Found that the model numbers are 8V0 407 811 and 8V0 407 812 for the two sides.

ProDarwin
ProDarwin MegaDork
1/19/22 10:58 a.m.

Why not 3d print some ducts?  You can make them fit exactly as desired.

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
1/19/22 11:05 a.m.
ProDarwin said:

Why not 3d print some ducts?  You can make them fit exactly as desired.

3D printing ducts that size could run into the triple-digits fairly easily, plus there's the design effort involved. Was hoping I could buy a pair of ducts that are close enough for cheap and rig them up.

hunter47
hunter47 Reader
1/19/22 12:25 p.m.

Unfortunately they're not as cheap as the GT3 ducts, but definitely cheaper than the alternatives. I've looked at try to make the Z06 ducts work but that requires more parts and dev work, and I'd rather just get a plug and play kit at that point. $62 USD is great, mine were $100 from ECS. 

kevinatfms
kevinatfms GRM+ Memberand HalfDork
1/20/22 8:08 a.m.
hunter47 said:

In reply to GameboyRMH :

I do like this idea. If I slotted the duct as well, I wouldn't even need to remove the endlink. I'd probably want to slot it to make some clearance for the endlink and FSB (Front sway bar, LOL), anyways. I'll try it out! If not, these were relatively inexpensive and was really just more of a fun project. Boomba Racing makes similar CNC aluminum scoops that mount to the control arm with hardware and are actually made for the car. Worst case scenario I buy those. I just didn't want them because they were twice the price and the scoops were small. 

I run the Boomba deflectors on my Fiesta ST and they are beyond exceptional. If you wait until a holiday they will issue a discount code which usually will place them under $120 a set. 

kevinatfms
kevinatfms GRM+ Memberand HalfDork
1/20/22 8:13 a.m.

The next best thing to 3d printing an entire duct would be a car specific bracket or set of brackets but with a universal set of lexan plates that bolt into the specific bracket. That way you dont need to print a single massive piece of plastic for a duct. Just the small bracket and use a universal piece of lexan(can buy from home depot). Secure it all with some stainless hardware. 

Looking at the picture of the Subaru control arm, there is one vertical bolt hole in the arm that could be used along with piggybacking on the sway bar hole. Make a bracket to bridge those two locations with two angled areas to attach a flat piece of lexan? 

hunter47
hunter47 Reader
1/20/22 3:19 p.m.

Yeah, the Boomba deflectors mount through that bolt hole.

J Speed(?) has a design similar to what you're talking about: 

\Greenline Motorsports - J Speed Brake Cooling Deflector Kit

Instead of Lexan it's some sort of softer plastic. 

I'm ultimately trying to get the RS3 ducts to work first.

hunter47
hunter47 Reader
1/29/22 10:10 p.m.

Zipped off the larger section of plastic and they fit just fine now.

hunter47
hunter47 Reader
2/2/22 12:39 p.m.

concerned with how high up it is (good thing for ground clearance, not for catching any useable air), I'm not sure if there's any considerable airflow to it and what does reach it is stagnant. I'll see about a NACA duct inside the fender liner/undertray that'll direct air from under the car into the wheel well. 

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