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Pontiac Fanboy
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I put the 997 GT3 brake ducts in the intended orientation (opposite of Glynn). I don't have any objective data proving that they work but I have done two track days with them on, and have Laguna Seca next weekend which is a tough track on brakes. The front edge is a little close to the subframe but that little slot in the leading edge of the deflector kind of fit nicely where the subframe edge is. If you look under the nose of the car you can see that scoops hanging down a tad, so it has to do something. I was really happy with how they turned out from a fit standpoint. I'll snap some better pictures of them when I get home later.
(y)
Interested in the pictures.
 

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GR-RRR!
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Discussion Starter #62
This clutch slave design is sooooo flawed. Whomever decided to put the fluid handling part of the slave inside right next to the clutch should be drawn and quartered. The Hondas I've owned have mostly had hydraulic clutches but the slave cylinder itself is on the outside of the bell housing and thus doesn't get the heat and dirt from the clutch and are incredibly easy to replace and bleed if the need arises.
 

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This clutch slave design is sooooo flawed. Whomever decided to put the fluid handling part of the slave inside right next to the clutch should be drawn and quartered. The Hondas I've owned have mostly had hydraulic clutches but the slave cylinder itself is on the outside of the bell housing and thus doesn't get the heat and dirt from the clutch and are incredibly easy to replace and bleed if the need arises.
Agreed. Slave on the exterior of the bell housing seems to make so much more sense (also previous honda owner)
 

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Discussion Starter #64
The only annoying thing about Honda clutch systems is their clutch delay valve (CDV). They are a little valve in the slave that slows down the engagement of the clutch a little bit to make things easier on the drivetrain, softens the drivetrain shock. However, this means when you are trying to make rapid shifts and engaging the clutch quickly (or dumping the clutch) the clutch engagement is slowed down about half a second. Which means the clutch slips a little more. Which throws off your clutch/throttle timing and just feels out of sync if you aren't used to a Honda clutch. The good news is, removing this annoying little valve is a relatively easy DIY upgrade, especially since the slave is on the outside. I did it on my current Honda when it was almost new.
 

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Clutch slipping would only be a result of a worn clutch and would not be affected by bad clutch fluid. If the fluid is bad, you would have a hard time getting the clutch to disengage, but it will have no problems staying engaged.

On the other hand, a worn out and slipping clutch would get very hot on a track day and would cause your clutch fluid to boil. So it's the slipping clutch causing the fluid to boil and not the other way around.
Yeah sure, I said it was a combination of the two because I knew I hadn’t done a full flush so there was probably some “stock” clutch fluid in there which I’m sure has absorbed water and boils easily. What confused me as after an instance of that non engagement period, it would work okay for the rest of the day.
 

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Discussion Starter #67 (Edited)
Personally, I think putting them on the "wrong" side makes them provide more air to the rotor. Putting them on the "correct" sides leaves the narrow end toward the rotor and overall terminating farther from the rotor thus spilling a lot of the useful air before it gets near the rotor. Having them installed as pictured above seems that a lot of the ducted air would be spilling rearward at about the radius rod bolt and more at the top above the control arm. Installed backwards at least gets the majority of the end of the ducts as far as the ball joints, the other way none of the duct even makes it as far as the ball joint. Just my thoughts.

FYI, when actually installed on a Porsche, they go to just past the ball joint.

I've posted my driver's side photo again here so folks can more easily compare the photos.
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I’m not sure I agree that air is “spilling” and losing efficacy, since it’s not really a duct. It’s there to grab air and direct it to the side, so visualizing the flow field, it just needs to increase flow in the “x” direction (side to side) to get more air to the area in the center of the rotor (rotor vanes are designed to spin air from the inside to the outside radially). I also like how the pickup scoops at the leading edge are oriented parallel to the flow, because it promotes a more gradual redirection of air.

As it is now the end of the deflector is about at the balljoint. If I were going to change anything I would just attach an extension to get it even closer.

We’re really just pissing in the wind until someone has some data comparing the two. As long as they are able to engage ABS all day and you are happy with your pad/rotor wear that’s all that matters 😃
 

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Personally, I think putting them on the "wrong" side makes them provide more air to the rotor. Putting them on the "correct" sides leaves the narrow end toward the rotor and overall terminating farther from the rotor thus spilling a lot of the useful air before it gets near the rotor. Having them installed as pictured above seems that a lot of the ducted air would be spilling rearward at about the radius rod bolt and more at the top above the control arm. Installed backwards at least gets the majority of the end of the ducts as far as the ball joints, the other way none of the duct even makes it as far as the ball joint. Just my thoughts.

FYI, when actually installed on a Porsche, they go to just past the ball joint.

I've posted my driver's side photo again here so folks can more easily compare the photos. View attachment 502898
Looking at the pictures or both installations, I feel like having the ducts on the 'correct' side actually make a bit more sense. I think its better to have the wider end toward the front to try to capture as much as possible and accelerate it toward the narrow end. In the opposite scenario, the narrow end toward the front may not be able to capture as much air for cooling and possibly decelerate the airflow toward the wider end as it delivers it to the rotors. In addition to this, the wider end toward the front would also be more capable of making the air turn almost 90 degrees toward the rotors whereas the narrow end would allow more air to 'spill over' and get very little air to actually turn towards the rotors.

And all of this is assuming that there is actually a decent amount of airflow there in the first place.
 

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Which is of course a pretty big assumption!

I feel like it is helpful to think about it more in terms of manipulating the static pressures throughout the flow field. Flow at “x” distance away from the duct experiences the effect at a diminishing degree as “x” increases. I’m on board with your train of thought regarding having the wider end up front. If I could though, I would like to try to slide mine closer to the hub, and if that’s not possible, try to add an extension or even just add another baffle behind the control arm to further increase static pressure inside the wheel area and catch the spillage at the trailing edge of the duct.
 

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I definitely agree with you on the goal of getting higher static pressure in the center of the rotor in order for it to get sucked through the rotor vanes. I've made myself some 3D printed brake cooling backing plates that directly feed airflow into the center of the rotors through a hose attached to the fog light opening. It should, in theory, deliver the stagnation pressure that would normally act on the surface of the fog lights (minus some losses through the hose) straight into the center of the brake rotor and force air to flow out through the rotor vanes. Another benefit of this, and the reason I invested a good amount of effort to do this on my car, is that it cools both sides of the rotor from the inside, as opposed to the surface on one side of the rotor only. I read somewhere that cooling the rotor from one side only could cause it to warp as one side expands more than the other.

Now, is this really important to any any of us, even if we track our car multiple times per year on HPDE track days? - No. But I just enjoyed doing this project for myself, and I enjoy discussing various ideas with other people. I actually did not know about these Porsche brake cooling deflectors before seeing them on this thread.

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Nice setup! Not sure why I didn't think of the 3D printed backing plates. Good to know they stand up to the heat too!

I saw the GT3 ducts on this forum a couple years back, and then again last year on Glynn's setup along with his 275 front tire fitment, and thought at $15 it was a real cost effective way to do something about brake temps. Even the new GT3s have a variation of the deflector ducts that just clip on to their control arms. I guess they are happy with the efficacy of them. Of course, I'm sure they also did some CFD on their car to make sure they were actually getting air which none of us have done but..... thoughts and prayers!
 

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Those spindle ducts are slick.
That's the kind of part I'd pay money for, but GTO aftermarket is GTO aftermarket...
 

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Nice setup! Not sure why I didn't think of the 3D printed backing plates. Good to know they stand up to the heat too!

I saw the GT3 ducts on this forum a couple years back, and then again last year on Glynn's setup along with his 275 front tire fitment, and thought at $15 it was a real cost effective way to do something about brake temps. Even the new GT3s have a variation of the deflector ducts that just clip on to their control arms. I guess they are happy with the efficacy of them. Of course, I'm sure they also did some CFD on their car to make sure they were actually getting air which none of us have done but..... thoughts and prayers!
Those spindle ducts are slick.
That's the kind of part I'd pay money for, but GTO aftermarket is GTO aftermarket...
Thanks! I just want to find a different spot for the air intake so that I can put the fog lights back in. But I also feel like that's a great spot with good airflow available.
I could technically remove them for driving on the street but it took me so long to route the hoses so they don't interfere with the wheels and I don't want to have to do it again..and I don't really daily drive it anyway.

If anyone is interested I could probably order new 3D prints and have them shipped directly to you just for the cost of the printing service, I think the 3D prints were pretty cheap. Though these would only work with the CTS-V 6 piston front brakes.
 

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Aside from the diff audibly complaining and locking up in the paddock, everything held up great!
 

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Discussion Starter #76

Aside from the diff audibly complaining and locking up in the paddock, everything held up great!
I've been on that course many, many times (in Gran Turismo on my Playstation). ;)
 

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Aside from the diff audibly complaining and locking up in the paddock, everything held up great!
Awesome few laps there. I actually know this track better than I thought too from all the different video games I've played on it. I knew all the corners coming up as I was watching the video. I really need to make some plans to drive there myself.
 

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Awesome few laps there. I actually know this track better than I thought too from all the different video games I've played on it. I knew all the corners coming up as I was watching the video. I really need to make some plans to drive there myself.
I know right? I thought the same thing watching your Road America video.
 
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