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.

I had a terrible time with silicone fluid, my clutch hated the stuff. I switched back to conventional and no more issues. I drive my car at least three times a week, usually more.

quote:

Originally posted by LF - TP 2511:

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

That Motive Products pump looks good, but I already have a Mightyvac pump which works good enough too, although the container seems smaller on the Mightyvac: https://www.lbusupport.com/asp...ges/MV6820action.htm
I went and bought some Valvoline dot 3/4, so I plan on using that. Will mix a little of that in a jar with the current fluid just to be sure if it mixes or not. If the two fluids don't mix in a jar, then I presume the current fluid has silicone base fluid in there. But since some say silicone is purple, I am pretty sure I have the non-silicone in all my cars anyway. With my Group 4, it looks like easy peasy, as I can access each of the bleed screws without removing the wheels, but it doesn't seem that lucky with the red 5S and black 5S. In the black 5S the rear wheels need to come off and the red 5S the front wheels need to come off. I presume I siphon off as much as I can with the wife's turkey baster, add some new fluid, and then bleed at each wheel to flush out each caliper one by one. Once I get the new fluid flowing by bleeding from one of the calipers, I presume I just go on to bleeding the other 3 wheels and keep adding some new fluid along the way as it draws it through. If I do it right, I would think no air would get in the system and the pedal would remain strong when all done. All the time protecting the paint real good for any mishaps, ha ha.

Damn, I wonder what I did wrong now on my Group 4. I bled at each of the brakes, all the while feeding new fluid into the reservoir. But now I hardly have any brakes at all. Brake pedal travels a lot and even when it reaches brake pressure about 1/2 way, the power is almost gone (I have to press it real hard to stop at all). Its almost like I have no boost. What the hey, maybe just try bleeding all again? I also noticed that at the end point when pressing the brake down I hear kind of a clunk noise and also feel it at the pedal. Retirement...this is what happens when I am retired and have time to work on things and "improve" things by myself, ha ha. Anyway, my unit is shown in the photo below. I wonder if at some point I had drained too much old fluid out to empty and then fed the new through. I thought I was careful at keeping some in the reservoir all the time when bleeding. Not sure if that would make a difference anyway. Any diagnosis help? I wanted to take my Group 4 to Huntington Beach to observe thong city in the 80 degree weather, but now am deprived...damn!

Front Trunk by JanDaMan, on Flickr

I am still lost on what I did wrong. Today I put my vacuum pump on the brake bleeders and found two were not holding a vacuum completely. I torqued them down pretty good, almost afraid to do it more, but still not holding a vacuum. Could it be that I still have air in those two lines, and that this air in the lines passes easier through a bleeder screw than brake fluid would? Anyway, will try bleeding again tomorrow starting at the passenger side rear, then drivers rear, then passenger front and then drivers front. I believe that is the order.

In the dusty corners of my head, I thought the sequence of bleeding had something to do with the brake switch/biasing valve. as in if done in the wrong order an internal spool would shift and block fluid. (something about preventing complete fluid loss if a line broke). doing a quick read of the shop manual, I didn't see anything like that and I this quirk might have been for some other hydraulic system.

So my comments are probably completely in error and not worth the trouble to read

I didn't read the entire thread on what and what not, you did, but the first thing you need to do is bleed the master.

I don't know which one you have. Some have bleed valves, some don't.

If your's is a don't then you HAVE to disconnect the lines coming out of it and fabricate a tube that connects to the output and curves back into the reservoir.

These things are very sensitive to not having been bleed.

It only takes a couple of pumps of the pedal to get the air out of it though.

Very low pedal is a sign of this and the power bleeder will not do the master from one of the wheel locations.

Hello
Since you're retired, you 've got time

Why don't you do the old school method (I always do)
Lift the back, bleed the rear brakes (starting with the longest pipe)
Lift the front and do the same ...
Just an idea
Philippe

It might just be your MityVac is faulty and not able to hold a vacuum. I replaced the seals on mine and it is working good again.
Your bleed hoses also need to be tight on the brake bleeders. Do not loosen the the bleeders too much, you will suck air from around the brake bleeder threads. You can take the brake bleeders out and wrap ptfe tape round the threads to stop that happening during bleeding.
If you still cannot get a good pedal after all this with your Mityvac, then you will need to do the old 2 person brake bleed with someone locking the bleeder after every downstroke of the brake pedal.
Make sure the master brake level does not go down low.
The order of bleeding the brakes you have is correct.

Jan and others,

The problems of fitting a vacuum line to each caliper bleed screw and making sure your supply fluid is sufficient are the primary reasons Garth and I both so highly endorsed a pressure bleeder.

I feel for your problems but professional repair shops gave up on the old school two man method years ago with professional power bleeders.

Now that a readily available and affordable home unit is available it is a no-brainer to make the purchase and make life easier.

Larry

Thanks for all the tips. I know my Mighty Vac is good because I can put my finger on the end of the same hose that I use on the bleeder screw and it holds pressure very good (needle does not move at all). Not sure why I would need to bleed the master though. In looking at Google images of diagrams of the internals of a master, it seems that if I am able to pull fluid through each of the bleeder screws, then that would mean that fluid is running from the resivour down through the master and through the bleed screws. But maybe that simple logic isn't reality of how it works. Maybe I am opening the screws too much and letting some air in during the process. As mentioned above I also saw on line where some say to use the Teflon tape or placement of some grease around the bleeder screw when bleeding. Anyway will give bleeding another try in the wheel order mentioned and see what happens with some grease on the bleeder screws too during the process. Could try the two person method too, but some mentioned that method makes the seals in the master push into areas of the master where the master walls may not be real smooth, and then potentially damage the seals. First, to cover my cars again with the wife's good linen just in case some fluid flips from the hose to car paint...ouch.

Thanks Larry. Is a power bleeder similar to the Mighty Vac where the vacuum unit pulls fluid through, or is that something different?

There are good and bad points on all methods, just use what works for you.
Even Stoptech & Wilwood recommends using the 2 man method..
http://stoptech.com/technical-...pers/bleeding-brakes
https://www.wilwood.com/m/tech...swer.aspx?id=10&no=1
Professional shops have to work with ABS systems where they sometimes set the ecu to prepare for bleeding.

DOES,

I had no luck bleeding the brakes with my vacuum pump. Got a friend to help with the old school push the brake pedal method and they bled out just fine.

Doug M

quote:

Originally posted by Doug M:
DOES,

I had no luck bleeding the brakes with my vacuum pump. Got a friend to help with the old school push the brake pedal method and they bled out just fine.

Doug M

For me I would have to put the wife to work on the brake bleed screw while I pump the pedal with a cold beer in hand. Could do that, but my vac pump seems to draw it through pretty good. I am taking my time more this time, opening the screw more gradual and using some grease around the threads of the bleed screw and watching bubbles. Just got done drawing from the driver side rear & now having a beer to prep for Superbowl. May try the passenger rear before kickoff. Also this time noting which caliper fluid is being pulled from in the resivour too.

If this more methodical approach doesn't work, will then just take it in as that just about reaches my skill level.

just throwing out another thought

are the bleed screws on the upper most part of all calipers?

quote:

Originally posted by JFB #05177:
just throwing out another thought

are the bleed screws on the upper most part of all calipers?

Always.

The two rear calipers went well, then went to the front passenger side, and not so well there. During the rear caliper bleed, both rear calipers are taking fluid from the front of the resouvour, and I made sure to keep that filled during the process. But on the passenger front, Just air and slight fluid comes out of that line. Even when I tighten the bleed screw down, there is still some bubbles of air coming through when I apply the vacuum to that bleed screw. Not sure where the air could be coming from. Bad bleeder screw or seat? I greased up that area of bleeder screw and vac hose and the grease seems to be in place. Will watch the Super Bowl with a few beers, and see if I experience the same issue with the drivers side front.

I have had my own home made vacuum system for a long time. It really helps flowing a lot of fluid; so much so you almost need some one to stay on the reservoir.

As with anything the details are what make it work. Here are 2 points.

1. I put thread sealant on the bleed screws which helps keep the bleeder form pulling air around the threads.

2. I open and close bleeder using ignition pliers from Seers. Always seems to work better then a wrench.

Also, it flows enough fluid I have put in several master in dry.

Second photo does not show pump attached but it is always attached and running when I bleed. The set up is also good for sucking out fluid from things like the master cyl, power steering pumps, lawn mower oil, etc.

Sounds like the rears are bled fully now. Being a dual circuit you don't need to touch these again.
The front passenger does not sound good.
Do you a balance / equalizer / limiter valve plumbed in there?
See what happens on the drivers front.

I was able to bleed at the front drivers side, but had to pump like hell and really open it up until pure fluid started flowing without air, and then I closed tight enough just to slowly bleed fluid only through the hose. So I went back to the passenger side front and at that spot I just get a combo of fluid and air through the hose (in fact mostly just lots of air). I have grease around the threads which seems to stay in place, so who knows where the air is coming from through the bleeder screw. Tomorrow will try and peddle bleed on that side and see what happens. I tested the vacuum at the bleeder again when it is closed, and it seems it holds fine. So I believe the screw and seat are ok. If that doesn't work, may then get a pressure bleeder as Larry suggested and try that out. Reading on the net, it seems to operate by pushing fluid through rather than pulling with a vacuum like I am doing. I wonder how a pressure bleeder would work with a 3 cap resivour like mine. I suppose ok, if the 2 other caps are air tight.