Brake Fluid Choice

[jtaphorn]

I checked the archives and found no recent posts on this topic. I am racing an FC in vintage events with LD20 calipers.

I had been using Ford Motorcraft Dot 3 and have learned that I am boiling the fluid when braking more aggressively causing a soft pedal toward the end of the session. I switched to a bottle of Motul 600 dot 4 and that problem was cured the next race.

What is considered the best choice for compatible brake fluid? What are others using successfully?

Thanks in advance

[Keith Carter]

I believe Castrol LMA is regarded well with this group. We also used Motul without any issues.

[kea]

We use Cartel 580 on everything that runs through the shop (F5 - F5000). It is a DOT 4, 580 dry boiling point (min wet, 410). Girling LMA dry numbers are south of that. It will mix with those fluids you have been using.
The earlier version, Cartel 570, DOT 3, was used by a customer of mine who, many years ago, was GT-1 National Champion.

[S Lathrop]

One caution that applies to any brake fluid you use: Once you open a can of fuild, use it or throw it away. Do not use fluid that has sat around the shop for more that a day or 2 after it has been opened.

Water is soluble in brake fluid and for each 1% of water absorbed by brake fluid, the boiling point drops 10 degrees. Brake fluid can adsorbed up to 15%,water depending on the type you have. That means that old fluid in you system can boil at 150 degrees lower that advertised on the can.

When I was running cars, I would change the fluid in the system every couple races and sometimes prior to every race where the tracks required heavy braking.

Now the new brake fluids available today are likely better than what was available 20 or more years ago. But the improvement may only be in the degree to which the newer fluid will become contaminated with water.

[fitfan]

FWIW - ive found changing it frequently to be more important that the what type or brand.

[Charles Warner]

One caution that applies to any brake fluid you use: Once you open a can of fuild, use it or throw it away. Do not use fluid that has sat around the shop for more that a day or 2 after it has been opened.

Water is soluble in brake fluid and for each 1% of water absorbed by brake fluid, the boiling point drops 10 degrees. Brake fluid can adsorbed up to 15%,water depending on the type you have. That means that old fluid in you system can boil at 150 degrees lower that advertised on the can.

When I was running cars, I would change the fluid in the system every couple races and sometimes prior to every race where the tracks required heavy braking.

Now the new brake fluids available today are likely better than what was available 20 or more years ago. But the improvement may only be in the degree to which the newer fluid will become contaminated with water.

You can use the gadgets that are designed to extract air from open bottles of wine, then seal the bottle. Fancier ones replace air with an inert gas.

[Jim Gustafson]

I also am running an FC with the same calipers in vintage racing. I've found that any name brand, DOT 4 synthetic, from Auto Zone or equivalent works fine. I race at Road America exclusively, and still brake pretty late (I'm 73). I used to change the fluid after each event, but have found that is not necessary.

Jim Gustafson

[S Lathrop]

You can use the gadgets that are designed to extract air from open bottles of wine, then seal the bottle. Fancier ones replace air with an inert gas.

I don't remember seeing those gadgets when I was racing myself. I did say that things have changed since then. And yes I do drink win. I never used one of those gadgets for wine or brake fluid.

[Charles Warner]

I don't remember seeing those gadgets when I was racing myself. I did say that things have changed since then. And yes I do drink win. I never used one of those gadgets for wine or brake fluid.

probably because you, like me, always finish the bottle.

[Rick Kirchner]

A while back I saw some guys selling brake fluid that had been vacuumed for exorbitant prices.

I have air conditioning tools, including a vacuum pump. Had an old pressure cooker from my mom that my wife will never use. Converted it to a vacuum chamber. Now I can put cans of brake fluid in there and pump the moisture out. Mine doesn't have windows in it, but if you haven't seen stuff boil at room temperature it's pretty cool. Back in the Navy production facility I worked at you would always vacuum epoxies. The stuff foams up and nearly doubles in volume before dropping back into the container absolutely clarified.

Not like I have to worry about moisture absorption out here like you guys do back east. The humidity here hasn't been in double digits since February.

I've found the ATE brand to be excellent for the price. You can't get the blue anymore. *******s from the DOT evidently have a law saying all hydraulic fluid for brake applications has to be amber in color, so they no longer allow the import of the blue.

[DanW]

A while back I saw some guys selling brake fluid that had been vacuumed for exorbitant prices.

I have air conditioning tools, including a vacuum pump. Had an old pressure cooker from my mom that my wife will never use. Converted it to a vacuum chamber. Now I can put cans of brake fluid in there and pump the moisture out. Mine doesn't have windows in it, but if you haven't seen stuff boil at room temperature it's pretty cool. Back in the Navy production facility I worked at you would always vacuum epoxies. The stuff foams up and nearly doubles in volume before dropping back into the container absolutely clarified.

Not like I have to worry about moisture absorption out here like you guys do back east. The humidity here hasn't been in double digits since February.

I've found the ATE brand to be excellent for the price. You can't get the blue anymore. *******s from the DOT evidently have a law saying all hydraulic fluid for brake applications has to be amber in color, so they no longer allow the import of the blue.

Kids saw the blue and thought it might taste good.... So.....

[stonebridge20]

I just bought 20 cases of GTLMA pints on Amazon at a great price and free shipping. We use it in every car that goes through the shop. Every bleed or full flush job is either 1,2,3 or 4 full pints. There is never any left over in the pint bottle to put back on the shelf.

[RussMcB]

I could be mistaken. Feel free to correct me ...

Recently I think I checked labels and found the ATE had a lower boiling point than some other bottles I had on the shelf (AP? Motul?).

I was surprised, because I always sought after the ATE Blue (and later gold when the blue couldn't be found).

[Garey Guzman]

I could be mistaken. Feel free to correct me ...

Recently I think I checked labels and found the ATE had a lower boiling point than some other bottles I had on the shelf (AP? Motul?).

I was surprised, because I always sought after the ATE Blue (and later gold when the blue couldn't be found).

Here are a few links. I only pay attention to Wet Boiling point because with the hydroscopic nature of Brake Fluid, even new stuff has dropped below "dry", even in "dry" environments. My FFs are fine with the Castrol Mike mentioned above but I would use something better for a car much above FF performance.

https://www.lelandwest.com/brake-flu...ison-chart.cfm

https://www.lelandwest.com/brake-flu...ison-chart.cfm

[stonebridge20]

Here are a few links. I only pay attention to Wet Boiling point because with the hydroscopic nature of Brake Fluid, even new stuff has dropped below "dry", even in "dry" environments. My FFs are fine with the Castrol Mike mentioned above but I would use something better for a car much above FF performance.

https://www.lelandwest.com/brake-flu...ison-chart.cfm

https://www.lelandwest.com/brake-flu...ison-chart.cfm

Never had a problem with GTLMA in 355 Ferrari challenge cars that would turn stock rotors to molten lava. Even my old 4 wheel disc diesel pusher with GTLMA in it had a solid pedal at the bottom of Watkins Glen mountain after smoking the brakes half way down due to a trailer brake failure. Well, not exactly at the bottom of the hill but across Main street in the parking lot is where I actually got it to a full stop. That was one hell of a ride !

[DaveW]

delete - wrong place