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Brake Ducts - Pipe directly to rotor, or deflector plate?

AdamR

AdamR

Car  Mk1 MX-5 (x3), Westy
Hi guys,

Currently messing around with fitting some brake ducts to my 172 Cup. Got arch liners out and carbon canister removed so a bit more space to play with.

My original plan was to run a 2" silicone hose from a custom made inlet where the fog lights were, strapping it to the lower wishbone pointing directly at the rotor. I've got one fitted but there's not a lot of space, had to squish the hose to clear the weights on the inside lip of the wheel!

duct11.webp

Since then I've seen a few links where people use ~100mm ducting and a deflector plate instead:

http://www.cliosport.net/forum/show...Featured-***&p=5609297&viewfull=1#post5609297

http://clio-motorsport.blogspot.com/2008/12/brake-cooling-ducts.html

Anyone done 'my' method before with success? I think I might be doing it the hard way, as the deflector plate method looks a LOT easier... However the other brake duct systems I've seen before seem to direct air directly at the rotor?

http://image.musclemustangfastfords...7_steeda_Q335_mustang+brake_cooling_ducts.jpg

http://www.britishracecar.com/JohnMcCue-MG-Midget/JohnMcCue-MG-Midget-DF.jpg

Cheers!
Adam
 
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Thanks for your input. I got a hose fitted aiming towards the rotor (fixing it against the lower wishbone) - it's out of the way of the tyre on full lock, but it doesn't point directly at the rotor... I think it's possible but would be a bit more work - I'll see how it goes!
 
I've simply got some CAF tubing running from the fog light holes. I didn't bother with deflector plates.

I would think a lot of air gets through, so it's better than nothing.
 
shiyan said:
Mind posting a picture? I'd be interested to see how you've done it :D
Click to expand...
No worries, I'll get one later for you :)

Shadowness said:
I've simply got some CAF tubing running from the fog light holes. I didn't bother with deflector plates.

I would think a lot of air gets through, so it's better than nothing.
Click to expand...
Yeah that's how I did it, took a lot of faffing around to find a route that didn't hang down too much, rub against the wheels/driveshaft etc though!
 
And that too - I'd forgotten about that!

Edit: Random off-topic - Dan, your site has some very sweet photos on it. Most photography sites with automotive sections just make me go 'meh, my mum could do that', but your photos are awesome dude :cool:
 
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There is no room to run a hose behind wheel and directly onto disc/hub via wishbone. Think thats the reason the cup race cars used deflector plates. The engine/gearbox prevent this.

Airflow through it using the foglamp surrounds isn't that good either imo due to the airflow around them rather than throught them. Not saying it does nothing (I have hoses behind the surrounds myself) just it isn't ideal.
 
AdamR said:
And that too - I'd forgotten about that!

Edit: Random off-topic - Dan, your site has some very sweet photos on it. Most photography sites with automotive sections just make me go 'meh, my mum could do that', but your photos are awesome dude :cool:
Click to expand...

lol thanks mate. Very much appreciated :)
 
Keith185 said:
There is no room to run a hose behind wheel and directly onto disc/hub via wishbone. Think thats the reason the cup race cars used deflector plates. The engine/gearbox prevent this.

Airflow through it using the foglamp surrounds isn't that good either imo due to the airflow around them rather than throught them. Not saying it does nothing (I have hoses behind the surrounds myself) just it isn't ideal.
Click to expand...
Makes sense - however I did manage to squeeze one in on the drivers side with one route (onto the wishbone), and another on passenger side with a different route (to a pipe that was mounted against the caliper). I'll grab a pic of the drivers side later, but taken the hose out of the passenger side now.

Yeah, their shape isn't ideal for scooping air in, guess the cup racer ducts were designed to do that better. I'm half way through making some new ducts for the fog light surrounds that should have a much better scoopability, I'll bob some pics up when done in case they will be of use to someone.

Shadowness said:
lol thanks mate. Very much appreciated :)
Click to expand...
No worries!
 
AdamR said:
Makes sense - however I did manage to squeeze one in on the drivers side with one route (onto the wishbone), and another on passenger side with a different route (to a pipe that was mounted against the caliper). I'll grab a pic of the drivers side later, but taken the hose out of the passenger side now.

Yeah, their shape isn't ideal for scooping air in, guess the cup racer ducts were designed to do that better. I'm half way through making some new ducts for the fog light surrounds that should have a much better scoopability, I'll bob some pics up when done in case they will be of use to someone.


No worries!
Click to expand...

Yeah please post pics up when you get chance. I was trying to run 108mm hose aswell.
 
Ah - I only had 51mm hose, which is probably why it worked... Will grab my jack and some pics in a min :)
 
I tested ours with a leaf blower and some smoke pellets(from any Plumbing &Heating supplier)and the deflector plate method works well.
 
Very good idea - thanks for that!

After more checking/tweaking (and from the info above) I'm definitely going to go down the deflector plate route.

The duct I had in (see below) seems to work from a very basic 'drive/brake the car hard then see how close to the wheel I can put my face before it feels like it's going to burn off' test (lol) - the one with the duct felt noticeably cooler - but the new 'scoop' (last 2 photos) should get a lot more air in as the cross sectional area is over double, plus it should 'catch' some of the air that's trying to go around the bumper. Need to rig up a MAF for proper testing, haha :D Probably going a bit far mind you...

Anyway, pics:

d1.webp

d2.webp

Crimped the hose to give more clearance, but looks like the wheel weights JUST scrub it on full lock. Also it's not pointing as directly to the rotor as I'd like...

d3.webp

New bigger scoop - will have a go at a deflector place tonight if I get chance.

d4.webp

d5.webp
 
Tony Hunter said:
Nice try but it looks abit vulnerable under there and don't think it will last very long.Our cup racers had deflector plates so go with this.
We used heat shield,easy to cut,easy to bend.
424.jpg

http://burpspeed.com/Burpspeed/Build/Entries/2010/4/5_Brake_Ducts.html
Click to expand...
Cheers for the link Tony! The location is fine as far as I can tell, doesn't hang any lower than the splitter, although I guess it would get ripped off with a gravel-excursion! However, I'm not happy with how direct the feed is to the rotor so have made a start on some deflector plates.

Shadowness said:
I take it you're not putting your arch liners back in?
Click to expand...
On my car? Well the passenger side one hasn't been there since I got the car, drivers side one is currently out. Are they just there to stop crap filling inside the arches? And try to prevent water/crap getting to the aux belt?
 
I think mainly for protection. I'd rather have peace of mind and keep them in, just to prevent any crap getting into places where I'd rather it didn't. I cut a hole in the liners for the pipe to go through, and cable tied everything down. Does the job nicely.
 
Here's what I came up with in the end. Moulded around an old water container I had lying around :D I wanted a curve as I'm positive this will be better for air flow, driving it towards the caliper and disc rather than having a right angle which surely just stalls the air...

scoop3.webp

scoop5.webp

Clearance on full lock...

scoop6.webp

scoop7.webp

The 'brace' at the rear of the deflector plate also sits up against the support strut that runs from the arch to the lower subframe, so the whole thing is nice and stiff.

Seems that the scoopy things I've fitted to the fog light holes do a good job too. Did two tyre heat cycling runs, the side without the scoop had a tyre temp (air temperature inside the tyre) 9 and 12 degrees higher than the side with the scoop! Will fit one to the other side as well and do something similar to confirm that though...
 
Yeah, that's a very fair point! I'll let you know when I've broken them and bust out the sheet alloy ;) haha.
 
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