Found some explanation of direction of vent in the apracing web site.
http://www.apracing.com/car/brakedisc/iden...ntification.htm

 

The direction of internal vanes works like a air blower in furnace or air conditioner (reverse direction of furnace blower see how much it effects performance) , air is moved from the center thru the vanes to get expelled out at outer diameter . The reason that some companies don't make directional rotors is cost , not performance . Curved directional vanes move a much greater amount of air through rotor . This keeps rotor temperature much lower . The rotor will pull air into the center because of low pressure created by air leaving through vanes . All you have to do to get air to move through rotor is spin the wheel . Every one talks about 4 pot , 6 pot , big and huge , brake clamping force is related to piston size not how many you have ( if you have 6 piston caliper add the area of all the pistons on one side , that is the effective area of force that can be applied to the rotor) . At some point the stock Honda master cylinder will not keep up , your petal will be at the floor . Larger pads don't increase braking capabilities at all, they just increase pad life . (big pads and calipers do increase weight) The single piston caliper on the stock S-2000 has effective area of 3.54 sq inches , a four piston caliper with four 1 -1/2" pistons has the same 3.54 sq inches of caliper area no increase in clamping force or increase in fluid requirement from master cylinder .

brad

 

Hey guys, we argued this point adinfinitum in the previous 3 threads. I agreed with you guys, that theoretically the vanes aid or hinder airflow dependant on direction.

But I was informed otherwise by Spoon, DBA, and several other (Luis et al) that actually did tests with on rotors to see if they heated any quicker or cooled less as a result of vane direction. None of ther results showed a difference.

According to all of the above the swept vanes are just for strength, and the air in the disks is so turbulent there is no turbine effect whatsoever.

Here is the quote from Mark Joseph of DBA

 

Ask some reputable source when you are in doubt.
When AP, Brembo are making their brakes for some antique race car, (spoon, DBA,etc) were even not exist at that time. See my AP website link at my previous post above.
The direction of the vane make a difference.

 

Well a big right back at you.

If you read the previous threads you'll note that I agreed with this theory. I even went to the trouble of drawing diagrams. I checked out your link and it says "The brake discs are handed and should be installed with the cooling vanes running back from the inside to outside diameters in the direction of rotation as indicated in the sketch.". It doesn't say, 'if you don't, one side will get hotter than the other'.

But the fact is, no one has presented any practical data to show that this theory has any measurable effect. And I'm big enough to admit I may have been wrong.

Let's just say I agree that the direction of turbine blades has an effect on cooling. Now it's your turn to present some imperical data that shows the quantity of this effect in road or semi-track cars. Or are you just basing this on an assumption built up from one paragraph of the AP website?

We're all waiting.

BTW
AP Racing 1967
DBA 197X
Brembo 1961
Spoon ????

 

[QUOTE]Originally posted by AusS2000
[B]

Well a big right back at you.

If you read the previous threads you'll note that I agreed with this theory. I even went to the trouble of drawing diagrams. I checked out your link and it says "The brake discs are handed and should be installed with the cooling vanes running back from the inside to outside diameters in the direction of rotation as indicated in the sketch.". It doesn't say, 'if you don't, one side will get hotter than the other'.

But the fact is, no one has presented any practical data to show that this theory has any measurable effect.

 

This'll be the last time I say this.

I agree with your theory!

The practical application however is what I question. So far all actual tests performed with relation to this theory (there are several in the previous threads. Some good, some not so good) have shown no difference between the rotors cooling ability. Until someone can show otherwise......

If you need some 'theory' to support this apparent contradiction of common sense, try 'it's so turbulent in there that the turbine effect is negated'.

 

AusS2000,

I understand you point now.

But the next question is, with the real world test data that posted on this forum, I think those brake company will know the same result too when they did their test a long time ago. Why are they still making those curved directional vane? It is more expensive too make those rotors than straight vane rotors.
Is that a market gimmik or their is other technical merits on that design?

 

Phew

The reason DBA make the rotors with swept vanes is that it lessens the tendency to crack radially (see their comment in one of the previous threads).

AP can put themselves in a good position by suggesting that the vanes should be directional even if they don't back it up with any real world data. A bit like arguing about the best wing spoiler for a Hyundai . Suddenly everyone (well, you, dwb1 and I ) are dubious about Spoon and DBA's rotors. Pretty slick really

But until it's backed up by real world data I won't have a bar of it.