Just rebuilt my entire braking system on the 72 so it's completely empty. I would like a brake fluid that's moisture resistant, (won't rust calipers) doesn't eat paint, and doesn't cost me my first born male child!! (Silicone is $25. a Quart ) Does Dot-4 synthetic fit this application? Teach me oh Corvette brothers...enlighten me oh wise ones.
Eddie

 

Dot 3 for me(i'm not racing)

 

I would stay away from Silicone, many will tell you that it's fine unless you have ABS. But even without ABS silicone will harm modern seals and it WILL NOT absorb water, therefore, you get corrosion quicker since the water is not in solution.

How are you going to drive the car?

If it's a pure street ride and then ATE SuperBlue or Type 200 (same thing actually) are great. They are very incompressible types so they give a nice pedal feel. And it's more than adequate for street driving and very good for heavy use too. And it has excellent anti-corrosion properties.

It's under $10 a liter. http://www.raceshopper.com/ate_brake_fluid.shtml

You can use any DOT 3, DOT 4 or DOT 5.1 fluid you like, just stay away from DOT 5.

 

Three years ago, I did the same to my 69 (including all new SS lines). I went with DOT 5 Silicone and I have been extremely pleased ever since. Absolutely no issues with the DOT 5. No moisture or corrosion "issues", no fading, and solid stops. I do not believe it is harmful to seals at all. I would use it again without hesitation.

As usual, you will see lots of negative hype whenever they are trying to sell you something else!

 

if you go to most auto parts stores there is a brake fluid that ford made for there HD diesel trucks that has a heat rating of around 550F. and it is very very very cheap. in canada we can buy it at like a canadian tire. and is about $5 CAN. for around 400ml's. it is good stuff i have have thrashed on it for a while now and hasn't boiled yet. this is what i am going to use for now untill i can afford some motul brake fluid. anyways thats prbly your cheapest solution.
Ryan.

 

Is the braking system really the place you want the cheapest solution?

We use a LOT (tens of MILLIONS) of o-ring seals here at work and every single one of them gets SILICONE lubricant. ALSO, these are EPA-regulated products that must meet initial and lifespan leak rates... As long as the seals are virgin (have not been in contact with volatile fluids), they will be fine. The only exception would be if the seals were designed to swell after installation, which our brake seal aren't. If they have been immersed in DOT 3 or 4, they will need to be replaced before switching to DOT 5. I'm not an elastomer engineer, but I believe the seals shrink and/or harden after you remove them from the DOT 3/4 fluids. You can imagine the complications from that.

My '68 has had DOT 5 in it for over 20 years. Internally, the system looks brand new and it has NEVER had the fluid replaced. Obviously, I don't recommend that, but I had no control over the previous owner's maintenance schedule. I'm overhauling the entire brake system this spring with VBP o-ring calipers, new MC, stainless lines, etc. and I intend (already purchased) to use DOT 5 fluid.

 

No problem with silicone once you get past sticker shock.

 

Start by reading this article:

http://www.stoptech.com/whitepapers/brakefluid1a.htm

As with most things, brake fluid is about compromises. DOT-3 will resist water best, DOT-4 will resist overheating best and DOT-5 won't eat your paint but will eat a hole in your wallet. The article will fill in the rest.

 

Don't understand your statement " DOT-3 will resist water best." The article you reference says...."DOT 3 and DOT 4 brake fluids are ether based and, as such they are hygroscopic in nature - i.e. they adsorb water at every opportunity." ??????

 

You're right. I wrote the above in a hurry. DOT-3 and 4 are very hygroscopic and will resist water damage to the brake system better than DOT-5 will. DOT-3 is somewhat more hygroscopic than 4 so will absorb water more efficiently but need to be replaced more often as a result. Sorry for the confusion.

 

Valvoline makes a synthetic DOT4. It's available from AutoZone (cheap). Because it's synthetic, it's less hygroscopic than conventional DOT3/4.

That's what I used during my last brake job because it's compatible with DOT3 and I wasn't starting fresh...

 

HUGE change
going
from empty
to
ANY brake fluid. :p:

 

Interesting article.... but I disagree with some of the generalizations made in it.

" DOT 3 and DOT 4 brake fluids are ether based and, as such they are hygroscopic in nature - i.e. they adsorb water at every opportunity. Since water boils at 212 degrees Fahrenheit (100 degrees Celsius) the adsorbed water dramatically lowers the boiling point of the brake fluid. A MINUTE AMOUNT of water suspended in the fluid decreases the boiling point as much as 1/3. Damn! The fluid in the system absorbs water through the breathers, through the caliper piston seals and by magic. Not only does this reduce the boiling point, the entrained water leads to corrosion of both ferrous and Aluminum internal parts. Double Damn!! So buy your brake fluid in small containers and don’t save the leftovers."

===> This one I agree with. This is why you have to change your fluid every year if you use DOT3/4.

"We won’t even discuss DOT 5 fluids as they are completely unacceptable to the high-performance enthusiast, but we’ll include them in the following table for completeness.
PROPERTY DOT 3 DOT 4 DOT 5
Dry BP (F)@ 0.0% H2O 401 446 509
Wet BP (F)@ 3.7% H2O 284 311 356
Chemical Composition Glycol Ether Based, Glycol Ether /Borate Ester, SiliconeBased"

===> True... DOT 5 fluid has a lower boiling point... so maybe all of us 001's wanna-be 007's shouldn't use it? My take on this is... if you really race, you will need to change your fluid regularly anyways, so DOT 3/4 is perfect for you. I know that some people do actually race their Vette's.... I used to autocross... but no more. I'll bet 95% or more Vette owners never really use their brakes hard... I mean really hard. So the boiling point issue is moot for them (myself included). I have DOT 5 in both my Vettes, and even in a panic stop, I have a rock hard pedal. So much for the "compressibility" issue. In a race situation, I'm sure it's a valid concern. But for street driven cars... nah.

"Believe it or not, one of a brake fluid’s most vital characteristics is its ability to absorb water. Yes, you read that correctly – brake fluids absorb water by design and that is really a good thing.

===> Again, in a race car, this is valid. In a daily driver... it is an untrue generalization.

By absorbig water in a daily driver, the water corrodes the entire brake system from the inside out. This is not good. It is bad.

"Whether we like it or not, water is everywhere and finds its way into everything. That’s just the nature of the beast. Even our brand-new sealed brake system will eventually absorb water given enough time."

===> Another generalization... My C2 was closed for 20 years with DOT 5, and there was not one drop of water inside when I finally tore it down. The fluid outlasted the seals.... and was still clear. I filtered out the seal particles and poured it back in the top... where it still is... working perfectly.

The article was slanted toward racing, and they made that perfectly clear, so I can't really fault them for the content. But taken "out of context" for face value, there is questionable value to some of the points.

DOT3/4 is best for racing... so if you'/re going racing, that's your fluid.
DOT3/4 works fine for daily driving if you RELIGIOUSLY flush it every year. If not, then it's not a good choice.

DOT5 can't be used for ABS because ABS agitates the fluid and people claim this introduces air bubbles. So if you have ABS, don't use DOT5.

DOT5 has a lower boiling point... so if you race... don't use it.
(Some forum members do race, and do use DOT5... go figure)

DOT5 doesn't eat paint. So if you get your jollies off on painted parts, DOT5 is a good thing. A caveat to this is.... don't spill it on any bare fiberglass... it will wicke into the fiberglass and it's impossible to get it out. DOT3/4 will also wicke into bare fiberglass, but it is easier to remove.

DOT5 compresses more than DOT3/4... Couldn't prove it by my Vettes... and very soon my Mustangs as well. Probably true... but my brakes work great with DOT5... hard as a rock. So I don't lose sleep over that one either. If the engineers say it compresses more, and they proved it by testing, (not bad science), then I believe them. I doubt many of us could tell the difference in a daily driver.

The internal seals will deteriate/flat-spot regardless of which fluid you use. So that is not a factor.

So...
check the runout of your rotor/spindle's and fix it if out of spec...
install the O-ring seals/pistons to reduce maintenance,
if you race load up with DOT3/4,
if you putz around town with painted calipers and your baseball cap on backwards, use DOT5.

Dot-4 synthetic eat paint? Anyone have an answer for that ?

Now... where's that horse?.... oh yeh... there he is...

 

Yes

 

DOT-5 silicone fluid does not eat paint and it does not require regular replacement. The other types all do.

You can install DOT-5 when you overhaul the brake system. It is not bad to use fresh DOT-3 to flush the system out in preparation for DOT-5 but you need to first replace anything that is made of rubber in the system before you put the DOT-5 in. The old DOT-3 will absorb water when used in the brake system over time and the fluid/water will soak into the rubber parts in the system. Later the contaminated DOT-3 fluid can leach out of the rubber parts and cause corrosion even with the new DOT-5 fluid installed. This is why they want you to do the change-over when you have replaced the whole system. If the system has all new seals/hoses/boots/cylinders in it, you can use the cheaper fresh DOT-3 to flush the lines out then install the DOT-5 in the system and you are good to go.

I have used DOT-5 in all of my old collector cars because I intend to keep them for a long time and I have enough other things on my to-do list besides maintenance. You can buy DOT-5 cheaper if you shop around online.

-Mark.

 

its not like DOT5 filled system is not gonna accumulate any water.

The water is still there and will pool instead of disperse, making it harder to ever rid the system of the water without a complete flush with denatured alcohol.

DOT3 and DOT4 absorb water so all you have to do is take a turkey baster and suck the fluid out of your MC once a year and replace with fresh.

I am starting to wonder if DOT5 has any merits at all. I would never use it again.

 

NO NO NO

DOT3/DOT4 AND DOT5 react and create a crud in your system. I know first hand because i didn't get all the DOT3 out of my system when i put the DOT5 in. The seals do not necessarily need to be replaced. I should have flushed my system with denatured alcohol like the guy at Zero Tolerance told me. I've had crap coming out of my system for years.

I wish i had never ever put DOT5 in. ITS A MISTAKE FOR EVERYBODY HERE. DON'T DO IT.

you'll never get all the DOT3 out well enough. If you run DOT5 you just as soon be running straight water.

 

Sorry, but I'm gonna have to disagree with that one...

If you clean out the system properly, there will be NO water in it. My C2 after 20 years proves that. I rebuilt the whole system initially, added the DOT 5, and 20 years later.... no water... no rust. That is proof the stuff works.

You must be doing something wrong.

 

if you spend a lot of time researching it you will see in many places that the water still gets in the system and actually pools. Once it has done this there is no way to get rid of the water other than flushing the whole system.

I would be willing to bet you if you actually used your brakes hard you would have had problems. But like was said earlier, most of the people here never use their brakes hard enough to have problems.

What i did wrong is putting in DOT5 without completely flushing the DOT3 out. It's very hard to do and will be the source of problems for most who make the swap. For that reason only its better to stick with DOT3/DOT4

 

"if you spend a lot of time researching it you will see in many places that the water still gets in the system and actually pools."

Is 20 years enough time spent on researching?

Let me try this one more time... my research consisted of a 20 year test. I don't have to do any other research. I removed the calipers and master cylinder from my C2. It does not have a brake switch/proportioning valve. I had the calipers sleeved, and honed the M/C. Rebuilt all the parts, re-installed them, and decided to "test" DOT 5. I drove the car for 20 years with no problems... I use Delco lip seals because they were still available. At 20 years, the calipers started to leak, so I tore the system completely apart again to refresh it. There was NO pooling, NO water, NO rust. Oh yeh... I forgot... I used the car for Autocrossing for about 10 of those 20 years.

Pooling can only occur if there is water in the system. DOT 3/4 DRAWS
water into the system each time you open the M/C to check the fluid level... and that's all it takes. Opening a system with DOT 5 will NOT draw water into the system. So... if you clean the system properly at the start, there will be no water forever after.

You are absolutely correct that the water will pool with DOT 5. But it can't pool if it isn't there to begin with. And it WILL NOT get in unless you let it. My 20 year test proved that.

Anybody who complains of "pooling" of water in a DOT 5 system has not completely removed the water to begin with, or has rotor runout so severe that "pumping" has introduced air & water into the calipers.

One more time.... system removed & overhauled, all water removed, DOT 5, 20 years, no water, no rust, no pooling. Autocrossed.

Not many people have the patience to do this job correctly... and when they have issues, they blame it on the technology. The master cylinder, brake switch, and all four calipers MUST be removed and MANUALLY cleaned out as part of the process. No fluid flush (including alcohol) will remove the goop that is built up inside the system, including the brake switch. I have a series of digital photo's of C3 brake system parts showing the goop.

I'll bet YOU that I can rebuild your brakes with DOT 5 and you will not have any such issues.

So when do we start?

PS- A very common mistake in doing this job is running compressed air. laden with moisture, through the brake lines. I have 4 air/water separators in my compressed air system, and even I am not satisfied with that.