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Painted Brake Calipers = More Heat Retention?

Old 03-08-07, 08:55 AM
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Painted Brake Calipers = More Heat Retention?

I've been thinking of painting or powder-coating my brake calipers, but after further thought, I realized I would essentially be insulating the aluminum calipers and causing them to retain more heat that might otherwise be dissipated into the atmosphere. Am I correct in thinking this? Or would the affect be so small that it wouldn't matter?

I mean really if it would increase the heat retained in the calipers by any amount, I think I'd rather just clean and polish them a bit and not use paint.

PS. Are the rear calipers made of steel? I noticed mine had a little bit of rust on them, so I guess they aren't aluminum? Maybe I'll just paint the rear calipers to prevent corrosion...
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Old 03-08-07, 11:48 AM
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Good question, get one of those craftsman temp probes and paint one but not the other and see, maybe we should start putting heat sinks or watercooling on our calipers?
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Old 03-08-07, 01:19 PM
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Yep, your right about heat retention and paint. In fact the smoother the surface the more it retains heat so polishing will do about the same thing. Now, on the street, does it matter? Probably not. Racing is another issue, you WILL get them hot and every little bit of heat dissapation helps. If you are worried about it, get some ceramic heat backing plates from HRP World and keep the heat from getting into the caliper in the first place.






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Old 03-08-07, 01:40 PM
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Heat

Flat black paint will give off heat. Bright colors like white retain heat and reflect it. Example: Paint the motor flat black / Paint the firewall white. Any school boy / girl should know this.
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Old 03-08-07, 02:45 PM
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Originally Posted by Dick Elliott
Flat black paint will give off heat. Bright colors like white retain heat and reflect it. Example: Paint the motor flat black / Paint the firewall white. Any school boy / girl should know this.
I think thats flipped, dark colors absorb light (heat)
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Old 03-08-07, 03:38 PM
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what everyone says is pretty much on target, I think. I have painted mine red, easy to clean and see leaks or problems. I run hawk blues, regular break fluid and NO ducts, and have not even a hit of brake heat problems and I typically hammer the brakes harder than the next guy, only advantage my underpowered ride has. So, I highly doubt you will have any adverse effects.

And I second Patman07...light colors dissipate heat, dark absorb. Based on the heat of a car interior, black vrs white. Just my thought, correct me if I am wrong. Good luck!!!!
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Old 03-08-07, 05:35 PM
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Light colors do not dissipate heat, they may reflect it, but they do not dissipate/radiate it.

Likewise, dark colors may absorb heat energy better, but this also has nothing to do with dissipation. Look at the number of heatsinks on electrical gear that are black.

The original poster did bring up a good question about painting or powdercoating calipers - it most likely does not improve heat dissipation and could certainly hurt it. A good clean surface is your best bet. A rough surface will most likely give better thermal transfer (to the surrounding air) than a polished one.

-bill

Last edited by wrankin; 03-08-07 at 05:41 PM.
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Old 03-08-07, 05:51 PM
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Alright well I think I will just clean them well when I rebuild them and that's it. Makes sense and saves some money anyway.

The second poster mentioned attaching heat sinks the caliper... seems like an interesting idea, only problem is there is generally not much room for that (at least not with my wheels) and it's probably more efficient to just use ceramic or titanium backing plates.

Thanks for the input guys.
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Old 03-08-07, 06:26 PM
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Originally Posted by RaceDriver7
The second poster mentioned attaching heat sinks the caliper... seems like an interesting idea
If you are that concerned about heat retention you need to be looking at recirculating the brake fluid rather than the miniscule effects of the caliper coating.
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Old 03-08-07, 06:35 PM
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I'm not THAT concerned with brake cooling at all. My thought is simply that since coating a brake caliper offers NO performance advantage at all, and coating it could potentially decrease performance (though I'm sure it's probably a negligible amount), then why coat it? The pros of coating don't really outweigh the potential cons.

I said heat sinks were an "interesting" idea, not a good idea. That's why I said using backing plates is a better idea.
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Old 03-08-07, 07:06 PM
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BTW, what do you mean by "recirculating" the brake bluid? I've heard of water cooling the brakes but I haven't heard of recirculating the fluid (though there are a lot of things I haven't heard of!)
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Old 03-08-07, 07:19 PM
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Originally Posted by Dick Elliott
Flat black paint will give off heat. Bright colors like white retain heat and reflect it. Example: Paint the motor flat black / Paint the firewall white. Any school boy / girl should know this.
Exactly. Prolly explains why Mazda chose to paint the oil pan black..............
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Old 03-08-07, 10:00 PM
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Paint your calipers and buy some titanium backing plates from gooroo and damian.
Aftermarket calipers are painted, so I going to guess that the performance loss is not much of an issue?
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Old 03-08-07, 10:44 PM
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Smile I must be a Girl.

Originally Posted by Dick Elliott
Flat black paint will give off heat. Bright colors like white retain heat and reflect it. Example: Paint the motor flat black / Paint the firewall white. Any school boy / girl should know this.
There are a few paints that increase surface area to remove heat. If you use standard paints it will not help but hurt.

If I remember my physic class in high school it is dark colors that retain heat and bright reflex heat. Remember walking bear foot on a black ash fault road and jumping from one cool white line to the next as a kid. That sort of proves my point. Oh if you havenít try it on a hot summer day then try it then you will understand.
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Old 03-08-07, 11:39 PM
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Black will absorb and radiate heat better than other colours, but any time you have an interface of two materials, even if it's just 2 pieces of the same material (two halfs of the caliper for instance) it creates a resistance to conduction. If the heat can't conduct to the surface of the paint very easily it won't get dissipated as quickly. I'd leave them, just give them a good cleaning.
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Old 03-09-07, 12:47 AM
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This thread is so nit picky, I love bullshitting about the most negligible(spelling?) things on forums.

Speaking of recirculating brake fluid, anybody done this for reduced fade/etc? Sounds like it could have some awesome potential, Brake fluid cooler?
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Old 03-09-07, 05:48 AM
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Old 03-09-07, 06:38 AM
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I believe the colors dont really matter since the heat is being generated by friction not LIGHT. If you happen to have brakes that harness light energy please let me know. . . A white pot in an oven at 350 degrees is just as hot as the black one. If you rub to pieces of sandpaper together one set white the other black I bet the temperatures on both will be similar. Heat in braking systems is from friction not the sun. If you are worried about heat do what others say and just run some ducts and or those backing plates. I have no experience with the backing plates but the ducts seem to work well for most Racecars.
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Old 03-09-07, 09:11 AM
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Colors

We're both right! It does both. Thats why the rad is flat black.

Originally Posted by Patman07
I think thats flipped, dark colors absorb light (heat)
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Old 03-09-07, 10:47 AM
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Just to clear this up... I think color does make a difference. Black is actually the absence of color - it looks black because it absorbs light instead of reflecting it. White and reflective surfaces reflect the most light. The colors behave the same way for radiated heat (same thing as light just in different wavelengths, mostly infrared, not in the visible spectrum).

Think of it this way: black allows heat radiation to pass through it. White reflects it, so the radiation does not pass through it as easily.

The caliper is heated mechanically through contact with the hot fluid and pistons. Here color doesn't really matter. But for the caliper to cool efficiently, it needs to transfer this heat to the surface of the caliper and radiate the heat into the air as infrared radiation. I think a bright or reflective coating on the surface of the caliper would prevent this heat from radiating to the air as well. Black would allow heat to pass through easier.

Of course choice of coating material matters much, much more. Coating a caliper with ceramic would probably not be a good idea. I was actually more concerned with the insulating properties of the material used in the paint rather than the color. Don't the high-temp caliper paints have ceramic in them?

If I were going to paint them, I'd paint them black, but I think I will just leave them as is. I'll probably powder coat the rear calipers for corrosion resistance, but they don't get anywhere near as hot as the fronts anyway.
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Old 03-09-07, 11:10 AM
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Originally Posted by RaceDriver7
I was actually more concerned with the insulating properties of the material used in the paint rather than the color. Don't the high-temp caliper paints have ceramic in them?
I believe most of the engine/hi-temp paints to have ceramic in them. I painted an extra set of calipers a while go using some black hi-temp engine paint. Honestly, the stuff is so thin I can't imagine it making that much difference. IMO if you are running that close to the edge of your brakes, it might be time to look at ways to reduce the heat transfer (like different backing plates mentioned earlier).

http://www.2dperformance.com/shims.asp

However, if it's a true competition race car, you'll have to deal with what the specs allow.
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Old 03-09-07, 03:37 PM
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So, by all this reasoning, you should paint your radiator black to improve it's heat transfer????

AARRRGGGGHHHH!!!!!

<*sigh*>
So much bad high-school physics, so little time...

-bill
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Old 03-09-07, 05:47 PM
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RaceDriver7, black is actually ALL colors combined, white is the absence of color. I'll go along with everything else you said though.

Heat is transfered three ways, conduction, convection and radiation. Brakes are cooled all three ways. Conduction through contact with the rim, then the rim is cooled by convection(as is the brake rotor) and they radiate heat and get hot enough to glow red so there is probably some infrared radiation going on there.

The rougher the surface, the easier it will disipate heat. Paint fills in all the roughness.

With the ceramic brake pad backers you can cook the crap out of your pads and not worry about heat in the caliper and fluid.
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Old 03-09-07, 07:20 PM
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Originally Posted by jgrewe
RaceDriver7, black is actually ALL colors combined, white is the absence of color. I'll go along with everything else you said though.
Noooooo... A third grader might think this because you may get "black" if you mix a bunch of different colored paint together, but technically black is the absense of color and white is all colors together. It all comes down to light. White light has every color in the visible spectrum in it. Black is obviously the absense of light. Surfaces appear black because they disperse or absorb light. If you look this up you will see that it is correct. Surfaces appear white because they reflect all light. That's why if you shine a blue light on a white surface, it appears blue. It just reflects whatever light hits it.

Originally Posted by wrankin
So, by all this reasoning, you should paint your radiator black to improve it's heat transfer????

AARRRGGGGHHHH!!!!!

<*sigh*>
So much bad high-school physics, so little time...

-bill
Yes and no... of course it's better to not paint it at all! That's why I'm not going to paint my calipers. But the point is that if you ARE going to paint it, black would be the best color because it would radiate heat the best. This is somewhat relative because it depends on the material the paint is made of too - ie. ceramic black paint is probably much worse than white paint made from some other material that conducts heat well.
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Old 03-09-07, 07:35 PM
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Damn, if you can believe wikipedia black is the absence of color. Thats what I get for listening to my art history major/artist wife! I guess the confusion is from how you mix to get black and what it ends up to be, "The perfect absorber of light".
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