Brake Ducts

[rex]

Hello,

I am opening a new thread concerning brake ducting. I am aware that there is another similar thread in the "General Area" but after reading it, it does not seem to answer my questions.
So... After having a NQSBBK for a couple of years I came to the conclusion that this is not enough for tracking even a 160bhp Golf. I find the kit awesome but I think that what I need to have a complete car (from the brakes point of view) is to have proper brake venting. I installed the RS3/TTRS brake vents but I want more.
I will try to explain what I am thinking about and if you guys think I am not on the right path or I might be doing something different please intervene.

After much consideration I think NeilM's solution



is only partially ok because I would like the ducting to be closer to the discs.

1. Where does the air come from?
Well, I think the best way to get air to the brakes is to get it from the open fog grilles. I, unlink a normal GTI driver, don't have the normal GTI (or opened GTI) fog grilles.
I have the RLine fog grilles (these can also be fitted to a GTI fender):





As you can see in the picture above, these fog grilles have a cover next to the fog light hole. This cover can be taken out or left in place depending on the driver preferences. This cover makes it really easy to create a brake ducts hole. I just cut a hole (the red circle)





and attach the brake ducts.

This is a very clean solution and without a negative impact on the looks of the car, because, personally, I do not like this:



2. Well, one end is done and another end remains. Now I have to attach the brake duct to the brake assembly. I am thinking that the best way to go is for the air to exist the brake duct and enter the disc vanes, thus cooling both regions of the disc. Something like this:





I saw that some people are not concerned by sending the air into the disc vanes and just redirect the air to one side of the disc:





I tried to find information about the right way to do it but I found nothing so I might be mistaking but this way makes no sense to me... By sending air to one side of the disc, that side of the disc will be cooler than the other one so no quite optimal in my opinion (again, if I am mistaking please correct me).
So, I am thinking of manufacturing a piece that will be attached to the mud guard (I do not want to take the mud guard off because this is still my daily drive) and will have an opening to let the air out and direct it to the disc vanes. Unfortunately I have almost no Photoshop skills (and I do not have a hub + disc + mud guard assembly yet in order to make photos and explain) but I hope you know what I am trying to say...



This is pretty much what I have in mind. What do you think?

Oh.... and one more thing... Since this is still my daily drive and since I have (and hopefully will still have) seen some track day action with cold weather (~4 degrees) I think I need a way to "cancel" the brake ducts with minimal effort. I saw some people duck tapping the intake of the brake ducts but I am looking for a more elegant and permanent solution. I am thinking of putting another piece between the brake duct itself and the final piece (the one attached to the mud guard) this piece can be taken out whenever I change the wheels and setup the suspension for a trackday. This piece will either allow or block the flow of air to the brakes. Is this a good idea?

Thanks!

P.S. Sorry for the long post.

[rich83]

The setup in that first picture wont do diddly squat!

It needs trunking all the way to the back of the disc to stand a chance of working.

[Janner_Sy]

I agree its far from the perfect solution, although it will fill the wheel arch with cool air which has no where else to go but through the alloys and arch gaps and maybe underneath.  But its better than nothing.

This looks to be a good idea.  Forcing air into the central hub area and then out through the cooling vents.  My only question is which way do the vents work. Does it suck cool air into the central hub area at the rear of the disc then push it out through the vents in the disc or does the air get drawn in from the outer points of the disc as it rotates and forced out through the cental hub at the rear of the disc?  If its the latter the above method might be wrong.

This was my  plan.  Its probably the simplest option and will no doubt be effective, but, your only cooling one side of the disc so will have a temperature gradient present between both sides of the disc so the pads will no doubt wear unevenly due t the difference in the temperatures etc.

Would like to see what DaveB has to say about this.

You also dont want to cool them down too much either, as you could then lose performance on your pads.

[rex]

richwig83 as I said above that is what NeilM has done to his car. I think that solution is better than no brake ducts at all. I am thinking that redirecting air in the wheel arch will create an area of high pressure thus forcing the air out of that area, cooling the brakes. As you say, and as I sail above I would like the ducting to be closer to the disc.

Janner_Sy we have similar opinions.
The disc vanes take the air from the hub:

[RENNTAG]

Intresting thread rex, I would be interested in improving the cooling to my nqsbbk

I think the disc vaines take air from the hub so forcing air into this area would be the best solution.

If the vaines were to vent air towards the hub i think this would cause problems bit brake dust being forced towards the hub which could cause problems in the long term.

How easy would it be to make up some ducts around the hub and test it out to see if there is a noticeable improvement?

[rex]

If the vaines were to vent air towards the hub i think this would cause problems bit brake dust being forced towards the hub which could cause problems in the long term.

How easy would it be to make up some ducts around the hub and test it out to see if there is a noticeable improvement?

Because of their circular movement and their shape the air must be taken from the hub (I think it is impossible the other way)...

I am thinking of buying a hub + mud guard (already have discs) and try to make a prototype for the air duct, but I can't test the design to have an objective result and see the benefits.
I am hoping for some improvement and only a small improvement is needed for a nqsbbk and a 160bhp Golf. Hopefully when I have the air ducts and some feedback you can try the solution and see if it works for you...

[jimk04]

Have you seen the oe Phaeton brake cooling set up?

[rex]

Yes, but not on a MK5 (as I remember Dave said he could not make that setup work for a Mk5). And also the air is not taken from the front grille but from underneath the car.

[Janner_Sy]

Have you seen the oe Phaeton brake cooling set up?

Nope, any pics?

[jimk04]

ETKA images were useless so Googled and found this - v interesting!

http://www.audiworld.com/tech/wheel60.shtml

[jimk04]

Oh just realised - phaeton has a trailing caliper - we have leading....

[rex]

Yup... they have a "double arm" (hope this is the English name) suspension and we have a MacPherson one.
All the audis (a4/a5/a6...)/vws (Passat B5, Phaeton) I know that have double the arm suspension, have a trailing caliper.

[the bruce]

Great thread, Rex !! To make things short:

Please do remove the shields. You'll never regret it. 

 

On a side note:

The issue is the trailing caliper + FWD incl. drive shafts making it hard to route a hose from front to hub.
Open fog grills into the wheel well + removed shields can decrease rotor temperature significiently by,
say, 50° C and more.
Don't mind about brake cooling in the winter. It doesn't realy matter if the pads have -10° or +50° C
compared to 500°C on the track. I even never felt any delay in the wet + salt.

BTW - engine bay, under bottom frontal area and wheel well are high pressure zones. Besides the car
(at your doors) there are low pressure zones. Knowing this you can easily imagine the average air flow.

 

[rex]

Please do remove the shields. You'll never regret it. 

The car is still a daily drive (I bought a Seat Ibiza as daily drive but I will still occasionally use the Golf also) and the roads in Romania have a lot of dirt. So, for the moment, taking the dust shields off is not an option... 

Don't mind about brake cooling in the winter. It doesn't realy matter if the pads have -10° or +50° C compared to 500°C on the track.

It is very had to get some heat in the brakes to make them work properly (as a daily drive) in winter...


Regarding the progress... I found a spare hub (didn't want to pay for a new one) and when I get my hands on it I will start with the brake ducts.

[rex]

Today I got some time and parts and I started working on the brake ducts...

First, here are the brake ducts (3m of them):



And the air inlet for them:





Then, I took one of my wheels off the car and I wanted to see where the brake ducts will fit best.



As you can see, there are 2 possible mounting points:



Above the sensor (I think this is the ABS sensor):



Or below the sensor:



Unfortunately when steering the car, if the brake vent is below the sensor, there is not enough room. So, only the position above the sensor is ok.

Next, I put the parts together in order to build a prototype...
Hub + bearing:



Nqsbbk J hook rotors:



As you can see, the air is not directed to the center of the rotors (and vanes). So I have to create a piece to direct the air towards the vanes:





And the finished piece:





Because the air inlet for the ducts is Aluminium I think I will make this piece out of Aluminium also and weld it to the inlet.
Next I will need to get my hands on a dust shield and see how I can attach the air inlet to it.
I will keep you posted!

Any advice is welcomed!