Brake fluid?

Hey 200,
Dot 3 and 4 are both actually "Old school" (polyethylene glycol-based). Dot 4 has a higher boiling point. I would not be concerned flushing my system with either...for fear the other was in it before flushing. Dot 5 on the other hand....totally different story.... 5 is synthetic.

I swapped to 5 once, but didn't like the pedal feel on the track. I ended up blowing the system out with air, then pushed a couple of cans of brake clean through the system..followed by air pressure blow out to dry the brake clean in order to switch back.

If you dip your finger into it, you can feel a viscosity difference between them. I'll go out on a limb and say the likelihood of it being Dot5 is probably pretty low.

My $0.02....

BTW...nice tidy trunk. I likey....

Thanks Rob, I am thinking non-synthetic too. Maybe it's just me, but here in So Cal it seems a bit difficult to walk in and get some Dot 4 off the shelf like it used to be. Dot 3 is all over the place. I will hunt around more though. May get some Dot 5 too while i am at it just to feel the viscosity difference.

other ways to possible tell which you have is
DOT3/4 will absorb (mix)small amount of water
when stirred DOT 5 will hold bubbles for several seconds

besides doing the cmparison "feel", you can also smell the differance

the silicone DOT5 should have a tint

quote:

but here in So Cal it seems a bit difficult to walk in and get some Dot 4

It's just a few clicks away!!!

http://www.saccrestorations.net/brake-fluid/

I'll admit, something like this I don't know much about. What exactly is the need for synthetic brake fluid? Synthetic oil I get, but not brake fluid.

quote:

Originally posted by Homer:
I'll admit, something like this I don't know much about. What exactly is the need for synthetic brake fluid? Synthetic oil I get, but not brake fluid.

Doesn't absorb water thus it doesn't have the issues with the water boiling at high temperatures which leads to brake fade.

From what I've read, DOT 3, 4 & 5.1 are glycol based fluid and many of those will say synthetic based fluid, and is either colorless or amber in color by SAE standards and very corrosive to paint, even if you happen to get some on your fingers and touch the paint on your car. They will absorb water over time and should be flushed depending upon use and conditions, usually one to two years.
DOT 5 based fluid is completely different and is silicone based, less moisture absorbent; however, is subject to air absorption and therefore will compress a little more than glycol based fluid which will leave one with a "spongy" or inconsistent brake pedal response. It should be purple in color.
Definitely, one does not mix DOT 5 with the others.

quote:

quote:
Originally posted by Homer:
I'll admit, something like this I don't know much about. What exactly is the need for synthetic brake fluid? Synthetic oil I get, but not brake fluid.


Doesn't absorb water thus it doesn't have the issues with the water boiling at high temperatures which leads to brake fade.

Hi Husker,

With all due respect, your response is completely incorrect. Water doesn't absorb, that is true. But INSTEAD of absorbing, it collects. Absorbing is a GOOD THING. Collecting is a BAD THING. When it collects, it causes all kinds of issues. Even worse in racing conditions. It could be used for a street car without any issues if changed on a regular basis. I know of quite a few people that use Dot 5 on their daily drivers. BUT, I wouldn't get the brakes very hot if I were them. The technical description from Wilwood is below for your reading enjoyment.

Scott

Due to the extreme operating temperatures of a high-performance brake system, standard off-the-shelf brake fluids are not recommended. Of critical importance in determining a fluids ability to handle high temperature applications is the Dry Boiling Point and compressibility.

The Dry Boiling Point is the temperature at which a brake fluid will boil in its virgin non-contaminated state. The highest temperature Dry Boiling Point available in a DOT 3 fluid is 572 degrees F.

The Wet Boiling Point is the temperature a brake fluid will boil after it has been fully saturated with moisture. The DOT 3 requirement for wet boiling point is a minimum temperature of 284 degrees F.

There are many ways for moisture to enter your brake system. Condensation from regular use, washing the vehicle and humidity are the most common, with little hope of prevention. Glycol based DOT 3 & 4 fluids are hygroscopic; they absorb brake system moisture, and over time the boiling point is gradually reduced.

Wilwood does not recommend using DOT 5 fluid in any racing applications. DOT 5 fluid is not hygroscopic, so as moisture enters the system, it is not absorbed by the fluid, and results in beads of moisture moving through the brake line, collecting in the calipers. It is not uncommon to have caliper temperatures exceed 200 degrees F, and at 212 degrees F, this collected moisture will boil causing vapor lock and system failure. Additionally, DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel.

Whenever you add fresh fluid to your existing system (never mix fluids of different DOT classifications), it immediately becomes contaminated, lowering the boiling point of the new fluid. For maximum performance, start with the highest Dry Boiling Point available (try Wilwood Hi-Temp 570 Racing Brake Fluid), flush the system completely, and flush it regularly, especially after severe temperatures have been experienced.

I stand corrected. Looking at my post I didn't word it very well.

quote:

Water doesn't absorb, that is true. But INSTEAD of absorbing, it collects. Absorbing is a GOOD THING. Collecting is a BAD THING. When it collects, it causes all kinds of issues. Even worse in racing conditions. It could be used for a street car without any issues if changed on a regular basis.

**********

Wilwood does not recommend using DOT 5 fluid in any racing applications. DOT 5 fluid is not hygroscopic, so as moisture enters the system, it is not absorbed by the fluid, and results in beads of moisture moving through the brake line, collecting in the calipers. It is not uncommon to have caliper temperatures exceed 200 degrees F, and at 212 degrees F, this collected moisture will boil causing vapor lock and system failure. Additionally, DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel.

So with these issues, why would people choose DOT 5?

Just to save their paint?


Rocky

quote:

So with these issues, why would people choose DOT 5?

Just to save their paint?

In a word, "yes"

I'll expand a little on what Scott said. The hill climbers were some of the first to use Silicone fluid due to the boiling point being higher then conventional fluid. They soon had brake failure but could not figure out why.

Turns out since it is not absorbed ANY fluid in the system will settle into the lowest point generally being the calipers. A drop or two of water in a silicone system is enough to boil water and to lose your brakes.

Conversely, traditional fluid can absorb a tea-spoon of water and basically spread it through the system and still not fail your brakes because you would still have a minute amount of water in your calipers.

Keep in mind we are suppose to change or flush our brake fluid every 2 years....but who does. I know I don't. In a street driven car it's 1 year generally for a silicon system and I would avoid the mountains at that.

When racing it I have always heard that if you use silicone fluid you are suppose to change it before EVERY SINGLE RACE.

Why do people like it? Because most people are not very good at bleeding brake systems without making a mess threatening the paint. I am in that boat too. I keep a bottle of Windex and a rag and immediately clean up any drop which does not get into the system.

But I also think the "silicone is great" movement is almost religious in nature. In fact I have seen issues in people cars with pure silicone oil while the mix seems to be ok.

The great benefit of silicone is it's industrial level of sliperyness. It has also been found that the silicon oil has some draw backs. One is it does not breakdown contaminants in the oil like natural oils. It is also so slippery that if you loose oil pressure say in a turn there is not enough adhesion and you fry your bearings a lot faster.

A lot of the problems can be fixed with additives but the more additives, the less oil. The best additive is traditional oil!

Back in the 80's Shell Oil came out with a full silicon oil for airplanes. Engines and controllable pitch propellers were not making it to overhaul. Turns out they were loading up with sludge and it would not break it down. They payed out millions in lawsuits and as far as a couple years ago there still were no full silicon oils for piston powered airplanes.

Turbines are different as there is no blow by in the oil system like in a piston powered engine. The silicone fluid has worked wonderful for turbines.

Hello Does200; Did you relocate your battery to the engine compartment?

Any pictures of the relocation installation?...Thanks!

Just to clear up any confusion in the previous discussion...

STOP SAYING "SYNTHETIC"

The issue with DOT 5 brake fluid has nothing to do with whether it is synthetic or not. It has everything to do with the fact that DOT 5 brake fluid is SILICONE-based. It's the silicone that makes it's properties so different from traditional old-school polyethylene glycol based fluids.

Now that that's out of the way, my favorite brake fluid for excellent price/performance is ATE Super Blue (Dry Boiling Point: 536°F / Wet Boiling Point: 392°F), and it's companion ATE Type 200 Amber (same product Amber in color). Alternating between the two makes bleeding your brakes a snap. You know you've finished flushing/bleeding the line when the fluid color runs consistent.

quote:

Alternating between the two makes bleeding your brakes a snap. You know you've finished flushing/bleeding the line when the fluid color runs consistent.

Garth shared this with me many years ago and it is a great tip.

For the frosting on the cake to make brake fluid changing much easier, by your self a Motive Products hand pump pressure bleeder tank. Even with the adapters you may need it's going to be less than $100.

One man brake, and clutch, bleeding in well under one half an hour from start to finish.

Larry

quote:

Originally posted by speedunlimited:
Hello Does200; Did you relocate your battery to the engine compartment?

Any pictures of the relocation installation?...Thanks!

Battery on my black car is in the front in a lowered battery box if you look close, with a small dimension PC925 Odyseey battery. Small but potent, that's what she said.

In my original post, I was more concerned about the internal brake components in choosing a fluid. Someone once told me to never use a silicone base in my red 5S, because of the brake build, so that is why I was wondering about my black car. Maybe silicone fluid doesn't do well with brake internals made with rubber components? Or maybe they didn't know what they were talking about, had investment in the non-silicone stuff, ha ha.

quote:

Originally posted by DOES 200:

quote:

Originally posted by speedunlimited:
Hello Does200; Did you relocate your battery to the engine compartment?

Any pictures of the relocation installation?...Thanks!

Battery on my black car is in the front in a lowered battery box if you look close, with a small dimension PC925 Odyseey battery. Small but potent, that's what she said.

In my original post, I was more concerned about the internal brake components in choosing a fluid. Someone once told me to never use a silicone base in my red 5S, because of the brake build, so that is why I was wondering about my black car. Maybe silicone fluid doesn't do well with brake internals made with rubber components? Or maybe they didn't know what they were talking about, had investment in the non-silicone stuff, ha ha.

Red cars don't have problems with it. Only black cars.

I've been using it in three high performance cars since about 1978.

If you bleed the brakes periodically you will bleed the moisture out of the system.

By the same token, you really need to do so with conventional fluid also.

Probably the best thing to do with all brake fluid is to replace it every other time that you need to do the pads.

Neither one should really cause havoc anywhere.

Why any kind of a racecar should have issue is probably because of lack of maintanence of the system.

You need to keep a log and service items periodically.

The craziest thing I saw with racers was that they were using recapped race tires.

They always looked scary to me but all things considered they were about as dependable as anything?

There are a lot of comparisons of brake fluid's out there, they are not all the same. The synthetic's generally have a higher dry and wet boiling point. Maybe of help when brake cooling is minimal.
https://www.lelandwest.com/bra...comparison-chart.cfm
Pegasus racing also lists the boiling points for the fluids they sell. The Castrol synthetic is only $69.99 a liter.. https://www.pegasusautoracing....ion.asp?Product=3343
I use the ATE amber and blue brake fluids and alternate them when bleeding brakes. When you see the color change the brakes are fully bled.

quote:

For the frosting on the cake to make brake fluid changing much easier, by your self a Motive Products hand pump pressure bleeder tank. Even with the adapters you may need it's going to be less than $100.

One man brake, and clutch, bleeding in well under one half an hour from start to finish.

Two enthusiastic thumbs up! I have one of these and it works like a champ! The only way to bleed your brakes.