This is about as close to the center of the rotor you can get, with or without the brake dust shields.

 

Hey Rob, I just read your drake duct DIY. You are now using 2.5" ducting.

I'm wondering where does the tires rub on the duct hose?
If you put the hose through the fender liner much higher (4 to 6"), like the Rev did in Photos post #27 above, would this be an improved location and less tendency to rub?

Thanks

 

I'm running 17x9 +63 255s up front and they only rub at full steering lock. I do believe that the higher hose mount would be better.

My hose gets rubbed where the zip tie goes around the sway bar mount in this picture:

 

Rob,

Instead of opening up the entire area where the flange mounts, what I did last time was leave it intact because the dust shield already has a bit of a funnel shape to direct the air to the center of the rotor. I realize it's a very abrupt funnel, so it reduces total airflow substantially, but it ensures that all of the air goes to the center. With my last car, I meant to open up the outlet hole a bit, but never got around to it. Nonetheless, it still seemed to kept the brakes cool enough to prevent rotors from cracking (though I still needed to bleed my fluid often).

With my new car, I was trying to explain that I might use both of these "funnels" on the dust shield with two smaller diameter hoses feeding them. I would think that coupled with the bigger calipers from the Accord (kudos to you for bringing this mod to my attention) should be enough to handle 255-width NT-01 or equivalent tires.

I'm also wondering if I should try to make a funnel inside the flange I use at the dust shield. That would smooth the airflow considerably and probably get a lot more of the air to the rotor. It also shouldn't be that hard to do.

-John

 

John,

I just don't think blocking available airflow to the inside rotor face is a good idea. The pros duct their air to the full rotor not just the center intake. I also don't believe this has much to do with rotor cracking. I cracked rotors before I vented the brakes and I cracked them after the vents. I really believe guys that don't crack their rotors aren't stressing their brakes like the guys that crack them due to driving style, speed or track configuration (but mostly speed ).

Rob

 

Depends on the car... I believe most of the higher $ race cars duct to the center.



This is from a Ferrari 430 GT car:



Apparently it uses the two duct approach -- one for the caliper and one to the center of the rotor.



This is from an Evo:



I've seen a variety of solutions on cars at ALMS races (as well as just blowing at the rotor face). I don't think there's as much consensus in ducting as one might think though.

I found most of these pics on a thread at http://www.nagtroc.org/forums/index....0/page__st__40

I would mostly agree that it shouldn't matter that much and is mostly just a driver thing. But I was the same driver in my last S2000 as I am in my new one and I didn't crack rotors with that one and already have with this one. That said, anecdotes like mine are to be taken with a big grain of salt.

-John

 

John,

Thanks for the homework and great pics. I had never seen a caliper ducted like that. It's too bad no one sells an oval flange.

With our limited size ducts and all the snaking around we have to do we're not getting all that much airflow to begin with so I'd still be hesitant to block airflow in the duct.

 

Maybe I missed it, if so sorry about that, but where are you guys getting the adapters that install on the dust/heat shield where the hose connects? What do these run price wise?

 

From my website brake duct how-to: http://www.aircraftspruce.com/catalo...uctflanges.php

 

Thanks to Rob and the OP. I can't wait to do this