Topic: Prototype DDM Brake Spindle Ducts

[kennysabarese]

So this is the prototype DDM product I was referring to the other day.

They are brake duct spindles which push air right up against the rotors. It is often used on race cars, and the SCCA recently allowed 3" ducts to be used on the Kappa for T2 according to our friend Bob Knowles.

It is possible to use fans to blow through these as well. It would be interesting to measure how much air is blown passively vs actively. NASCAR uses fans, and I'm sure other racing cars do as well. But most are passive so I'm sure this is fine.

Here is a photo of the product, next to the part it replaces.

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Supporting parts used:

10' of high temp duct: These range in price from 20 to 120 bucks depending on the heat range. I found some online for about 80 bucks.
I didn't cut the hose until I knew exactly how much would be needed. Eventually found that you can cut it into 3 equal lengths, 3'4" each and so I have one length as a spare.
(4) 3" clamps
Something to tie down the duct to secure it, I used wire cuz I didn't have any long zip ties.

The install of the driver's side took me an entire day, because I had to figure out the best way to route the hose to clear the tire and fit right. Once I had a proven install. The other side took me an hour and a half.

To install the spindle plate, you have to remove the calipers and rotor. I took the pads out of the caliper, then closed the caliper again before removing it. Don't let the caliper hang from the brake lines, I put it on a jack stand.

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To remove the rotor take off the little locator screw, it's a T27 Torx. If you've never removed your rotors, you will have to bang the crap out of them to get them off. Don't hurt the rotor surface, use a rubber mallet.

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Here is the hub with the rotor off:

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Now that the rotor is off, you need to disconnect the wire behind the rotor. I assume that's the wheel speed sensor for the ABS. I stuck a screwdriver under here to make it separate easier, than once apart removed the bottom from the bracket by pinching it and pushing away from you.

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[kennysabarese]

Then you have to remove the hub, these bolts are the same size as the caliper bolts: 15mm. There are 3 of them, and they can be a little tough to get to.

As you take the hub off, notice the position of the ABS wire so you can put it back the same way. It may not matter, but I choose to put it back the same way it went on. The hub and the stock shield will fall off together.

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With everything off it looks like this:

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Once you have this off, put it right back on but with the DDM duct plate remembering to rotate the hub so that the ABS wire is pointing in the right direction.


When the plate is on your ABS wire bracket thing may be in the way of the duct. It's a 10mm bolt, loosen it up and rotate it out of the way and connect the wires, to each other than back into the bracket.

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Now just put the rotor back with the torx screw, it doesn't need to be tight, then the caliper and pads back.

Here is the view of the plate and the rotor showing that you will get great air coverage across the entire face of the rotor:

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[kennysabarese]

Now for the duct. I choose to use the GXP/RL stock duct. (If you have a 2.4 you are on your own here) It has to be pushed as close to the middle of the car as possible to get the duct to clear the tire when you are turned all the way left or right, so I had to cut a part of the wheel liner off. This also opens the section where I choose to route the duct. For the driver's side I pulled the liner out so I used a jigsaw to cut it. For the passenger side I was able to leave the liner on and just use a utility knife to make the cuts. Here's how much I cut off.

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Cutting this exposes the mystery bar on the driver's side, which at first I thought was a problem because I was going to run the duct against the frame rail, but turned out to actually help.

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With this part cut out it allows you to pull the stock duct out easily. It just kinda slides out. Then part has to be trimmed down in order to keep it from sticking into the wheel well too far and hitting the tire. So I put the clamp on and tightened it. Because it's not a perfectly straight tube, when you tighten it, it will flatten out and show you the max amount you can cut off and still have significant section of plastic to clamp on to. So I just used a jigsaw to cut around.

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Next I attached the duct host to the stock duct, I first put the foam thing on the hose, than the clamp, then put the duct over the plastic duct and clamped it down and put the foam over it.

Stick the duct back into place.

Then I had to figure out the best way to route the duct up to the rotor. I tried a bunch of different ways:

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Frustration!!!!!!!!!

[kennysabarese]

Finally decided to go this way. I put the hose through the mystery bar, then between the swaybar and steering, then past the coilover and to the mounting point.

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This is the passengers side of course without the mystery bar:

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Then just had to make sure that there was enough slack when turning the wheel one way and not too much slack when turning it the other way. It ended up working out really well.

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Lastly I used a little wire to pull the duct a towards the center of the car for some more clearance. Though I don't have a pic of this right now. It's near where the mystery bar is. Also smushing the duct helps as well. The duct has a metal running through it for support so it holds it's shape and is reversible if you smush too much.

So that's it!!!

This writeup makes it seem like it was easy, but it was very very difficult for me to figure out the best way and make sure it would fit without too much rubbing or hitting the tire. I had to install the tire and lower the car because you can't accurately see if the duct will clear the tire when the car is on jack stands. I guess you could jack the suspension up and down, but I didn't think of that until just now. Also it's very difficult to see if the tire clears the duct when the car is on the ground and the wheel liner is in place. It was a real !

UGH!!!!!!!!

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 Luckily if anyone else chooses to install these, you won't have to go through the same struggle.

The true test is to drive and turn and hope you can hear any rubbing. I haven't heard anything yet or seen any wear on the duct so I think I'm good. I'm going to have someone walk beside the car and listen while making turns.

I'm off to the track this weekend and will report back on if this all holds together!

Thanks DDM!

[Helios]

Nice write-up. Thanks! Looks good, but I don't think the majority of us will ever have the need for this particular upgrade.

[Uranium-238]

DDM is making it hard for me to not say "To hell with B-SP..."

[kennysabarese]

Do AXers use brake ducts like this? I didn't think it was really necessary in AX.

[elff]

You can say F*#k BSP
Which then puts you in FP
Kind of appropriate.

This is pretty cool. Great writeup. Looking forward to hearing how they work out on the track.

[Sly Bob]

Nice write up Kenny and this should be a great addition to your car and others that track theirs.

[kennysabarese]

This is pretty cool. Great writeup. Looking forward to hearing how they work out on the track.

It's hard to know if they make a difference unless I plug them up one run and unplug them the next and see if I overheat my brakes. But that's not really a risk I am willing to take

In my scenario, my brakes can never be cool enough, so it can't hurt.

[DeepBlueGXP]

lots of work going on there, great write up, looks like a project I won't be doing


did you see my wheel liner thread

[Uranium-238]

Do AXers use brake ducts like this? I didn't think it was really necessary in AX.

That's a good question. If they're legal to use in whatever class a car is in I'd have to say every little bit helps. Most auto crosses you don't get a lot of cool down time between runs, so it may help with the later runs. Granted if you're not getting fade in those late runs why bother? We'll have to hear from you about how well they perform and go from there.

[elff]

Longest run I've ever done in an autoX was 70 seconds.
I just can't see that heating up the fluid, pads or rotors

[Uranium-238]

It might depend more on the group and what sort of course layouts they prefer. My first AX I boiled the stock brake fluid, switched to good old ATE super blue and didn't have any issues...till I went to Cumberland. There they prefer more open layouts with real straightaways, and on my last few runs I had some serious brake fade. That was five ~1 minute runs with a couple minutes of cool down between runs, with air temps in the upper 90's at least. Point being one run isn't enough to heat things up too much, but several successive runs with no cool down add up.

[scoobyless]

Looks like a quality product, but it looks like they are only sending air to the inside rotor face which is anything but a balanced cooling effect.  Usually a brake duct should direct air to the inside of the rotor hat so that it gets pulled out through the veins which is very difficult on the kappa, so difficult that I have not made a brake duct for myself yet.  Basically there is no opening to send air through to get into the rotor hat. 

Best way to test them would be a before and after on a days with similar temps/conditions on the same run. 

Definitely a great idea but I'm not sure if it's the best application of the idea, I'd love to see some data supporting the product.

[kennysabarese]

Looks like a quality product, but it looks like they are only sending air to the inside rotor face which is anything but a balanced cooling effect.  Usually a brake duct should direct air to the inside of the rotor hat so that it gets pulled out through the veins which is very difficult on the kappa, so difficult that I have not made a brake duct for myself yet. 

Can you show an example of one done the way you describe?

[ChopTop]

I Googled/Images/Brake Cooling ducks and found a lot of different set-ups shown, most appear to direct air to the back of the rotor.

This is the most interesting set-up,
http://www.google.com/imgres?q=brake+cooling+ducts&hl=en&safe=active&sa=X&tbm=isch&tbnid=Nsl7EvGo4bVcxM:&imgrefurl=http://forums.pelicanparts.com/porsche-911-technical-forum/500327-brake-cooling-different-apporoach.html&docid=5FeXmdTg-yhdBM&w=600&h=449&ei=ro86Tu-nI6m20AH6udjdAw&zoom=1&iact=hc&vpx=252&vpy=71&dur=10567&hovh=194&hovw=260&tx=146&ty=129&page=7&tbnh=135&tbnw=191&start=114&ndsp=20&ved=1t:429,r:6,s:114&biw=1141&bih=728

But it looks like it's a full-on race set-up.

[Dave@DDMworks]

When you do full race setups you want to push the air directly at the center of the rotor to create high pressure there, which forces more air through the vented rotor and out the ends, which keeps the rotor cooler. The problem with doing that on the Kappa, is the uprights that are on the car almost cover the entire center section of the rotor from the back and prevent any easy way of feeding air directly to the center of the rotor.

Here is a picture from a car that is pushing the air directly at the center of the rotors. The car (which was labeled as a mustang) has smaller uprights, which allows greater access to the center of the rotor to allow the hose to blow directly at it. Although even this setup is not ideal, as usually you try to seal the air coming in with a backing plate to help force it through the rotor.



Here is a quick rendering of the back of the upright on the Kappa's:



So the Kapps's are good in the face that it kinda seals up the center section of the rotors with the upright, but bad in the fact that there is no really easy way to get air into there also.

Hope that helps,
Dave

[kennysabarese]

Great info guys. Dave what do you think of this kind of setup that chop top mentioned that blows into the vanes. I can't tell if that huge hose is blowing into the center of the rotor, but if you blew into both parts I would think you wouldn't flow as well.

This is chop top's linked photo

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Speaking of Mustangs the Boss 302 Laguna Seca edition comes  stock with brake ducts like Dave has shown.

[ophidia31]

Problem: No air getting to the inside hat area of the rotor.
Solution: Get bigger rotors that open the area in the hat to more air from a brake duct.

[wspohn]

I doubt that cooling ducts would be needed on a slalom car that has a good choice of fluid, but who knows, as has been pointed out, some courses can be hard on brakes if the runs are close together.

This all brings back memories of race cars whose drivers had miscalculated when fabricating ducts like this. You could tell which ones they were because when they used full lock, the tire would catch the duct and they'd end up trailing yards of dryer tubing that had come undone like a giant Slinky and was now trailing behind the car, at least until they ran over it with the rear wheels and it ripped away from whatever was holding it on the car.

You need this sort of thing on a race track, but probably not on a slalom course and certainly not on the street.

A couple of tricks we used in the old days.  Lead the duct to what looked like a beer can with a slit across the side just down from the end. Mount the slit over top of the rotor just in front of the caliper and hook the duct to the other end and it blew air over both rotor faces. Useful where you couldn't get air into the hat centre.

In those days we didn't have large open wheels like the Kappa, and there was a problem getting air out of the rotor area.  Some Datsun 240Z racers came up with the bright idea of machining a Corvair engine fan (nice alloy piece with curved blades) so it could be mounted to the outside of the wheel using small bolts. As the weel turned the fan drew air through the wheel and out.  Not much use these days with such open wheels.  No one ever complained about rust on rotors in the old days as you could hardly see them inside a 14" or 15" wheel!  They'd wonder what the Kappa owners were on about not wanting to see any rust on the disc!

Of course in those days the cars were also light (a Corvette weighed less than a modern Kappa) so things change.

[kennysabarese]

Problem: No air getting to the inside hat area of the rotor.
Solution: Get bigger rotors that bring the pad surface out for better braking and and also open the area in the hat to more air from a brake duct.

NOOOOOOOO please don't turn this into a big brake thread PLEASE.

Lots of people have brake setups the way this is done and they are just fine. Lots of people race Kappas without brake coolers so this is just a little extra protection.

[Dave@DDMworks]

Great info guys. Dave what do you think of this kind of setup that chop top mentioned that blows into the vanes. I can't tell if that huge hose is blowing into the center of the rotor, but if you blew into both parts I would think you wouldn't flow as well.

This is chop top's linked photo

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Speaking of Mustangs the Boss 302 Laguna Seca edition comes  stock with brake ducts like Dave has shown.

I just read the thread where the picture was taken from and here is what they are doing:

Typical forced air system for TransAm brakes. Large duct feeds eye of rotor. Smaller, forced air duct leads to clamshell air discharge fixture for both friction surfaces:

They are also spraying water into the air stream to help cool the brakes even more.

Just read a little more of that thread and Ashley Page is the commenter in the thread - user name - bertpage. We have met him several times as he runs a company up in North Carolina that does brake design and is very good at what they do. Their company name is Prosystem (http://www.prosystembrakes.com/), small world on the internet sometimes

[kennysabarese]

I just read the thread where the picture was taken from and here is what they are doing:

Typical forced air system for TransAm brakes. Large duct feeds eye of rotor. Smaller, forced air duct leads to clamshell air discharge fixture for both friction surfaces:

They are also spraying water into the air stream to help cool the brakes even more.

Just read a little more of that thread and Ashley Page is the commenter in the thread - user name - bertpage. We have met him several times as he runs a company up in North Carolina that does brake design and is very good at what they do. Their company name is Prosystem (http://www.prosystembrakes.com/), small world on the internet sometimes

Whoa, since when should we actually read the description instead of trying to figure out what is being done in a picture we know nothing about. Sheesh!

I'm going to read it now. But I'm happy with what I have!

It's going to rain this weekend so I'll have that water spraying without having to pay for it!

[scoobyless]

Can you show an example of one done the way you describe?

If you google "RCE Brake Ducts" you'll see info on a subaru kit that directs air to the inside of the rotor hat, a much easier task than on a kappa.  I can tell you that the original kit, as simple as it may look, went though tons of on track testing and adjustments before brought to market to make sure that it was effective and didn't cause issues.

I did say that the kappa was very difficult to do this with, which DDM supported with pictures.  My biggest concern with throwing air at the inside rotor face is that you are cooling it unevenly which is never good with a rotor and it could cause issues depending on how effective the duct is at cooling.  If you are just using air from the front of the vehicle I doubt you will have much of an issue but I also doubt you will have much of a bennefit, but I could definitely be wrong.  That's why I was hoping for some data from testing in the near future.