Topic: Brake reservoir "racing" cap

[snaponbob]

Either OFF his meds, or has consumed too MANY of them at the same time.

[Ben L]

Sounds like it will be a spring ritual for me, as I dance around wearing nothing but flowers in my hair I will change my brake fluid, and sing ring around the rosie.

That is a most disturbing image. Don't get any on you.  Brake fluid, that is.

[snaponbob]

That is a most disturbing image. Don't get any on you.  Brake fluid, that is.

Ben, stop it. It's starting to sound like THIS !!!!!!!!!!!!!!!!   

http://www.youtube.com/watch?v=ZUabDrfjATY

[snaponbob]

Man, I LOVE youtube !!!!!

[kennysabarese]

I'm going to try to see how hot the brake fluid in the reservoir gets after some hard driving

[Sol Asylum]

Hey Goat since your the egg spurt now.

According to basic thermo dynamics raising the pressure causes the boiling point to also rise  (think about the pressure rating on a radiator cap).  How does that play into the boiling point of brake fluid because if you are standing on the brakes the pressure is now higher?  If the reservoir was pressurized wouldn't that help keep the fluid from boiling?  Of course you would have to disregard the fact that a pressurized reservoir would most likely cause the brakes to lock.

Don't you just love when theory and reality intersect?

[snaponbob]

  Of course you would have to disregard the fact that a pressurized reservoir would most likely cause the brakes to lock.

Gee !!! Ya THINK ??????

[Sol Asylum]

Gee !!! Ya THINK ??????

Anyone can be a dumb ass but you have to know what your talking about to be a smart ass.

[snaponbob]

Anyone can be a dumb ass but you have to know what your talking about to be a smart ass.

Um ...................... thank you ?   

[Sol Asylum]

Um ...................... thank you ?   

Actually I was referring to me being the SA, but uh I guess your welcome.

[snaponbob]

Actually I was referring to me being the SA, but uh I guess your welcome.

Well, there IS room for two.

[U4EA]

Well, there IS room for two.

Yes,........   both of your OPINIONS are showing.....    without them we would not get answers! 

[kennysabarese]

oh btw here is a photo of my brake fluid leaking and I have DOT4 ATE Superblue fresh right before that track event. not sure if it's from boiling or from being shook around.

[snaponbob]

Kenny, is it as full as it appears in the picture?

[kennysabarese]

it was a little high there. i took some out so it was about halfway between max and min and it made no difference.

also everyone i have talked to agrees that reservoir size shouldn't effect temperatures, so i'm going to go with the cap.

[lil goat]

How does reservoir size not effect temperatures? There is more fluid to dissipate heat, pretty simple concept, it's this thing called physics. Will it solve the problem, I don't know but for the life of me I can't see how the cap will and in the original TSB they spoke of changing the RESERVOIR and the CAP, I am changing both, the larger reservoir comes with a different cap. From talking with the guys at ASD the best solution is bigger brakes so you need to do less braking, therefore less heat. I went with the larger reservoir mostly because our clutch and brake reservoir are combined, just seemed like a good idea. I would think lighter wheels would help the problem as well, less unsprung weight, I knocked off almost 40 lbs with new wheels and will knock off another 20 or so with the new brakes, and it will be off the front wheels. Better tires mean better braking as well, that would reduce heat.

Just a side note, seems funny to me how many people will go out and buy every power adder they can find and not get better tires at least. There needs to be a balance maintained. Or you end up like the guys at the gym who only do curls, huge biceps and skinny legs.

(take a look at what our best autocrossers have done to there cars)

[kennysabarese]

bob from page 1 of this thread

"As for fluid heat, not arguing but rather just "thinking", I sort of wonder if the hot fluid at the calipers is really going to migrate through the lines, proportioning valve, ABS pump, master cylinder, etc., to the reservoir."

I've asked some folks I trust as well and no one thinks much fluid moves between the reservoir to the lines. I have been searching for evidence that it does, but haven't found anything yet.

I guess the best way to test this is to go drive and do some aggressive braking, then bleed the brakes immediately and see how the temp in the reservoir and the temp in the lines differs?

If you just measure changes in reservoir temperature I don't think it would be accurate because the engine compartment will heat the reservoir.

[kennysabarese]

But on the other hand, why did GM put it there in the first place if it didn't matter.

[lil goat]

bob from page 1 of this thread

"As for fluid heat, not arguing but rather just "thinking", I sort of wonder if the hot fluid at the calipers is really going to migrate through the lines, proportioning valve, ABS pump, master cylinder, etc., to the reservoir."

I've asked some folks I trust as well and no one thinks much fluid moves between the reservoir to the lines. I have been searching for evidence that it does, but haven't found anything yet.

I guess the best way to test this is to go drive and do some aggressive braking, then bleed the brakes immediately and see how the temp in the reservoir and the temp in the lines differs?

If you just measure changes in reservoir temperature I don't think it would be accurate because the engine compartment will heat the reservoir.

I have to say WTF on this one, if you put a pot of water on the stove by your theory, only the water on the bottom should get hot, not how it works, it's not the fluid per say that moves it is the heat, heat transfer through fluids in a confined space is pretty constant, if the fluid is hot at the calipers it will be hot in the reservoir pretty quickly, that's why it boils. That is not a Kappa problem it is a brakes in general problem. The engine compartment is not the problem, it gets hot but not that hot on the side where the reservoir is, if it was getting that hot the paint would be peeling.

Bleed hot brakes have you lost your mind if it is hot enough to boil Dot 3 that would be 289 degree's I am not going near anything that hot! If it boils Dot 4 at well over 300, you must be kidding.

[snaponbob]

it was a little high there. i took some out so it was about halfway between max and min and it made no difference.

also everyone i have talked to agrees that reservoir size shouldn't effect temperatures, so i'm going to go with the cap.

Probably right on all counts. I guess I get a bit of brake fluid on the outside of the Master Cylinder, but never really worried about. On ALL my Solo cars I have never had to add fluid. Apparently other stuff happens in higher gears!!!

[kennysabarese]

I have to say WTF on this one, if you put a pot of water on the stove by your theory, only the water on the bottom should get hot, not how it works, it's not the fluid per say that moves it is the heat, heat transfer through fluids in a confined space is pretty constant,

I would assume the same.

I can't think of a way to prove either theory. Do you have an idea?

[lil goat]

Being an old techie, and I do mean old. I think in terms of heat sinks, bigger heat sinks dissipate more heat. So I got the bigger reservoir (you know I couldn't spell reservoir until these threads started). The second point made by ASD, that improved performance means less heat makes a lot of sense. I watched the guys that had good times on autoX and they came into the turns FAST, then braked very hard, many times locking the rear brakes, I can not do that with my current brake setup, just not enough brake. It makes sense that using the brakes hard for short periods would generate less heat, than the slow progression (see brake failure going down hill) so better brakes means you can use them less. I know the best way to improve braking (and reduce heat) on any car is to improve the tires.

[snaponbob]

I would assume the same.

I can't think of a way to prove either theory. Do you have an idea?

Infra temp "gun". Certainly, as Jim says, if the water in the bottom of the pan is boiling, ALL the water in the pot will achieve that temperature. I would think, however, that if the brake fluid is hot enough to "boil" it would be inside that particular caliper and a fairly transient situation. Given that the fluid does not circulate through the system but rather moves back and forth with master cylinder movement, it would seem that for 3-400+ degree fluid to significantly effect the fluid temps in the reservoir, those temperatures would have to be transmitted through many feet of hoses and tubing, and through the proportioning valves and ABS system without radiating any heat along the way. Kenny, next time you are at the track, locate the brake lines under the M/C, and put your hand on them !!! My guess is that they will be about the temperature of the engine compartment. If I am wrong, rub some aloe on the blisters and cuss me out right here !!!!!  

[kennysabarese]

I think it will be tough to do a controlled and accurate collection of the brake fluid reservoir temperatures without outside factors getting in the way.

If you fill an hourglass with water and put it on a stove, will the water on bottom get hotter first?

[snaponbob]

I'

I think it will be tough to do a controlled and accurate collection of the brake fluid reservoir temperatures without outside factors getting in the way.

If you fill an hourglass with water and put it on a stove, will the water on bottom get hotter first?

I'll avoid THAT by saying that the hourglass will probably explode shortly after one sees bubbles !!!!