Latest wacky idea: Water-cooled brakes

Back story: I was thinking about putting a brake vent system on my 'rolla for more on-track endurance, but my mechanic said that brake vent systems only buy you another lap or two on the small tracks here, regardless of other brake mods. Not a good deal considering the trouble of fitting the system and the heavy costs of getting the parts into my hands here.

So lately (like...during lunch) I've been researching the water-cooled brakes used in Aussie V8 supercars. They use one of two types depending on how much cooling power is needed, one that injects mist into an otherwise conventional brake vent system, and for events where extreme brake cooling is needed, they inject a solid stream of water straight into the center of the brake disc vanes.

I'm thinking if I had the latter type, I could hit a button when my brakes start to get greasy to rapidly cool them on-track.

In terms of making the system it would be no problem, I could fab it up with a couple of washer pumps easy-peasy and pretty cheap. The question is, should I? Could this system lead to brake disc cracking? I'd be sure to only activate it while moving.

Edit: Problem I just remembered: My rear brake discs are not vented. Keep in mind low-pressure spray nozzles are an option.

Found this system for the R35 GTR that injects a mist into the center of the vanes:

http://www.willallracing.com.au/gtrbrakes.htm

I figure that wouldn't cause cracking so easily. For the rear discs a set of misters in the dust shield could work.

Edit: Also found a very useful post at the bottom of this thread:

http://www.aus300zx.com/forum/archive/index.php/t-299039.html

Guys I have spare rotors. I think I'm going for it!

I had experience with using water to cool brakes. I worked part time on a Trans Am race car in the last 80's and early 90's. We used a water mist sprayed into the brake cooling air ducts. We never did the direct on the rotor approach. I would think that the shock cooling could just reduce the life of the rotors by causing internal stress which could lead to cracks. Not a good thing. The team I worked for lost a 3rd place finish when a rotor shattered and took them out late in a race.

Most of the time the water cooling was use was for street races which had a lot of tight 90 deg. turns followed by short straights that didn't allow enough time to cool the brakes before having to be used again. At tracks like Watkins Glen, Road America, etc. we still had the water cooling but the driver only used it if he thought it was required. A simple switch to the pump did that. Wire up a relay from the brake light switch to activate it.

Interesting...so another option is to go with a conventional brake vent system w/ mist, for safety. Kills the cost savings, but it would perform better since I'd also get constant airflow and I could be pretty sure it won't break stuff.

To mitigate the thermal shock, you could wire the spray to come on only when the brakes are applied to prevent them from heating up rather than trying to cool them down. Better yet, for the most control use a three way switch- off/triggered by brake lights (via a relay)/on.

In the OneLap of America, Honda Alabama used hair dryers (set to "cool") to vent the brakes of their Odyssey.

To save $$$ you could try modifying one of those misters in the garden section.

Off highway logging trucks up here have done that for 100 years. Not too fancy though. Massive water tank and a hose to each drum.

Mmadness wrote: In the OneLap of America, Honda Alabama used hair dryers (set to "cool") to vent the brakes of their Odyssey.

Sounds like pretty much the same thing as a conventional brake vent system, except you're taking the energy from the car's electrical system rather than its forward momentum. Still a very interesting idea, it cuts down mounting difficulty and could be good for cars where it's not needed often since there's no additional drag.

The problem with direct-contact spraying-while-braking is that on the rear, I'd have no choice but to spray on the friction surface.

Audi tried it on some of the S1 E2s. That's why some of the footage from fast gravel rallies like Finland will have steam pouring from the wheels as the car flies by.

Is your low weight, low HP car REALLY putting that much strain on the brakes?

Fresh fluid and proper track pads aren't getting the job done?

Haven't tried it with DOT5.1 and Hawk HPS pads yet (with discs all-around now)...but these small tracks cook everyone's brakes.

Race teams years ago tried water cooling on drum brakes.

I'd say you don't have the proper pads.

I'd think if liquid cooling them worked well, nobody would have bothered pouring all that money into carbon and ceramic technology.

Though it might be worth a shot on known wheel bearing eaters. Cooling the hub being the primary concern, brake cooling would just be a nice side benefit.

Buy track pads and actually see what happens, I can't imagine you needing anything more than proper pads.

HPS are not proper track pads.

check back in the early 1970s... the Group 2 Ford Capri's used a water cooling system(illegally) while competing against the BMW's

Kenny_McCormic wrote: I'd think if liquid cooling them worked well, nobody would have bothered pouring all that money into carbon and ceramic technology.

Perhaps. Carbon-carbon brakes are F1 tech, and F1 is so heavily constrained by rules that it's a big mistake to assume things about the technical merits of various systems based on the use or non-use in F1. Look at the tire sizes used in F1, for example. :)

Even if they were allowed, carbon-carbon brakes might well be superior in F1 due to weight.

There was a setup I saw some years ago, using one way valves and extra lines to circulate the brake fluid through the calipers and up to the reservour to help reduce overheating the brake fluid.

Nothing is tougher on brakes than a Cup car at Martinsville. They use a brake fluid recirculator and small electrical fans to blow air into the center of the rotor. http://www.colemanracing.com/Brake-Recirculator-P3775.aspx

I was thinking about this on the way home and tried to do the math in my head, about how much do your rotors weigh?

In my mental arithmetic I came up with about 2 oz of water would cool a 5 kilo rotor 100 degrees

z31maniac wrote: Buy track pads and actually see what happens, I can't imagine you needing anything more than proper pads. HPS are not proper track pads.

This. Unless you are putting a crazy amount of horsepower through some super sticky tires, I don't see how your little car is going to overpower brakes, especially on a short track.

Get some Hawk Blues, Carbotech XP-10s, etc.

ProDarwin wrote:

z31maniac wrote: Buy track pads and actually see what happens, I can't imagine you needing anything more than proper pads. HPS are not proper track pads.

This. Unless you are putting a crazy amount of horsepower through some super sticky tires, I don't see how your little car is going to overpower brakes, especially on a short track. Get some Hawk Blues, Carbotech XP-10s, etc.

This +2

Hawk DTC-60s rock.

Using HPS pads on a race track is like using bicycle brake pads. Get real racing pads. And then stop using them so much. Get on them HARD then get OFF them. 99% of my students are using the brakes too much and dragging them for comfort. Stop that.

foxtrapper wrote: There was a setup I saw some years ago, using one way valves and extra lines to circulate the brake fluid through the calipers and up to the reservour to help reduce overheating the brake fluid.

DPI Dan Press Industrys used to make such a system. tried it and gave it back to the guy who owned it. It works but i did not like the feel or extra pedal travel.

I ran my ZX2SR on several different tracks, never had a brake problem. Used HPS and HP plus pads. Always bled the brakes. I also cleaned the rotors with every pad change. The car had good airflow to the brakes and through the wheels. Ran 20 minute or so sessions in high ambient temperatures. No fade ever.

It's possible for sure. This photograph is from 2000, at Shannonville Motorsports Park, at a Thousand Islands Zed Club lapping event. (I'm the passenger with the Scottish flag helmet in the 1972 240z)

The car behind us is a 300ZXTT with home-made water-cooled front brakes. The owner (both owners, in fact - are machinists at Royal Military College, and quite handy)

The brakes worked pretty well (you were worried about cracking - I don't remember that ever happening), but mostly I loved the novelty effect of seeing a cloud of steam shoot away from the car once every few laps.

ProDarwin wrote:

z31maniac wrote: Buy track pads and actually see what happens, I can't imagine you needing anything more than proper pads. HPS are not proper track pads.

This. Unless you are putting a crazy amount of horsepower through some super sticky tires, I don't see how your little car is going to overpower brakes, especially on a short track. Get some Hawk Blues, Carbotech XP-10s, etc.

I am going to say this as well. I have no idea how much power you have but at the weight of your car and on a rationally sized disk with proper pads you should be more then fine.

I have trouble even getting my race pads to seat properly on the ACR without covering up my brake vents and beating the ever loving tar out of my DTC-70's. That's with stock rotors.