Air brakes on a Subaru?

[JC]

I thought this was an interesting thread.

http://bbs.legacycentral.org/viewtopic.php?t=22529

JC

[sperry]

IBMattR

I think air brakes are actually wonderfully engineered systems... that are totally unecessary on vehicles under 10,000 lbs. There's really no reason to try and pull that off on a car. Plus there's really no room on a car for those huge calipers, the compressor, the air tanks, the lines, etc. Nevermind the cost of building all that.

It's an interesting thought experiment, but anyone that went down that road is just gonna waste a ton of money, and would still get out braked by someone on stock brakes.

Now, if we're talking about expensive/crazy brake mods, let's talk about water cooling!

[MikeK]

I just want to know if they'll last a whole track day!

[JC]

Originally Posted by MikeK

I just want to know if they'll last a whole track day!

Only one way to find out!

[Dean]

Originally Posted by sperry

Now, if we're talking about expensive/crazy brake mods, let's talk about water cooling!

It is the recirculating brake fluid option that interests me. You already have a fluid with decent heat capacity properties in the calipers, why not use it...

[sperry]

Originally Posted by Dean

It is the recirculating brake fluid option that interests me. You already have a fluid with decent heat capacity properties in the calipers, why not use it...

It's complicated, and certainly *far* more expensive than just buying the retarded expensive fluid that can take the heat.

[Dean]

Originally Posted by sperry

It's complicated, and certainly *far* more expensive than just buying the retarded expensive fluid that can take the heat.

I think it is cheaper than water cooling though unless you are just spraying water on the rotors which would be against the rules in most any series I can think of...

[sperry]

Originally Posted by Dean

I think it is cheaper than water cooling though unless you are just spraying water on the rotors which would be against the rules in most any series I can think of...

Running a variable pressure, flowing, closed loop brake fluid system is cheaper than just flowing water through the calipers and a heat exchanger?

I can't even imagine what a master cylinder or calipers pistons that allow fluid to flow through them would look like! A secondary system that flows water would be far easier to engineer... just add some water channels to the calipers, some hoses, an electric pump, and a radiator. And if the water cooling system fails, there's no mechanical/hydraulic connection to the actual braking system.

WRC tarmac cars use brakes with 6-pot water cooled AP calipers.

Those crazy European Super Truck beasts use a simpler spray system, note the steam:

[Dean]

It would look like this...Linky

And are you sure that is steam, not just dust/smoke on the super trucks? I can't imagine a series that allows water sprayed anywhere near the track surface. I think Intercooler sprayers are even a no no in most series for that reason.

[sybir]

Dean, Scott speaks the truth. Water is sprayed directly on the caliper and rotor to try and cook off some of the blistering heat you get trying to crank down an 8000 pound truck on a road course

That's also why you see lots of Supertrucks spinning out under braking

[Nick Koan]

Originally Posted by Dean

It would look like this...Linky

And are you sure that is steam, not just dust/smoke on the super trucks? I can't imagine a series that allows water sprayed anywhere near the track surface. I think Intercooler sprayers are even a no no in most series for that reason.

There is no way the water sprayed on the calipers has any hope of dripping onto the race surface

[sperry]

Originally Posted by Dean

It would look like this...Linky

And are you sure that is steam, not just dust/smoke on the super trucks? I can't imagine a series that allows water sprayed anywhere near the track surface. I think Intercooler sprayers are even a no no in most series for that reason.

Hey look! More than twice the failure points of a normal brake system, and only 4 times as expensive! And I'll bet it increase braking efficiency by 0% and reduces brake fade by 10% (and probably 0% over a water cooled secondary system). Where do I sign up?

If your brakes are really getting so hot, you need to cool the fluid, you're not running the right fluid. If your brakes are getting so hot the calipers need more than air cooling, a more simple water cooled system will work just as well, and won't drop the pedal to the floor if there's a failure.