OMFG- It's another brake question!, The same one again, and again, and... Options

[SGB]

(IMG:style_emoticons/default/chair.gif)

Been learning about brake fluid here alot lately. I certainly did not realizr why some fluids were more desirable. Of course, now I see that the boiling point is the critical measure, but which one? Is that "dry" number really only good the first 12 hours after the bottle is opened, or does it take more significant contamination to result in a "wet" boiling point? Here is the south we run 70- 99 % humidity most oof the time.
To frame my question-
I've got my first PCA DE with my car coming up. I've got valvoline synth in the lines, almost a year old:
Appearance Pale, Yellow Liquid
Dry ERBP F 503
Wet ERBP F 343
Viscosity @ -40°C 1800 max

Would it be worth it to flush and fill with Super Blue (382 wet bp, 536 dry bp)? I don't wanna fry my calipers, but I am a CSOB. Maybe flush & fill with new synth? How far in advance of the DE?

Any enlightenment would be appreciated.

[mudfoot76]

For the DEs in my region, 'They' always suggest that your brake fluid should have been flushed out within the last 6 months. _IF_ the color looks good to you, at the very least, you should bleed each caliper. The safest option is to flush your braking system out with brand new fluid.

In the paddock, I see some guys who bleed their calipers after every session.

[John]

We use ATE super blue in the track car and it is fine. We used to use Castrol LMA brake fluid (when you could get it in quarts) and it was fine as well.

I flush the fluid (run about a quart through the lines) prior to each event regardless of time since last flush.

You can do what you want. If it was me and you like the fluid you are using and it works well, by all means keep using it. Just flush it regularly and it should be good. Where most get into trouble is that they don't do a good flush and any old contaminated fluid in the system will create tiny air bubbles (from the water in it boiling) and you will have a soft pedal.

Your brakes will be good if properly bled with fresh brake fluid.


just my $0.02

[Trekkor]

use Motul.


KT

[DanT]

Pentosin DOT4

It doesnt matter what fluid you use, since this is your first DE you will probably over brake like every rookie and need to bleed your brakes during the day.
make sure to take your stuff with you to the track

[Matt Meyer]

In general:

Dry is probably the more important one but.......

Brake fluid is hydroscopic, it absorbs water. Right out of the air. So wet is not unimportant.

You will not "fry your calipers", you may boil your fluid.

Is the synthetic you are using compatible with DOT3 & 4 systems. Some synthetics are not (DOT5).

Synthetics are desireable because they absorb less water so "wet bp" is higher and they should last longer

Racers change their fluid more often to ensure their fluid is close to the dry boiling point. They get the brakes/fluid hot degrading the fluid so it wont last as long.

Your fluid is probably fine. IIRC, Porsche does not recommend flushing more than every two years. However, if it were me I would flush and replace with a quality DOT 4 fluid such as Super Blue.

DO NOT put fluid in your system from a previously opened container, or from a plastic container that has been sitting on your shelf for an extended period of time. Brake fluid will absorb water sitting on your shelf, if opened. I'm not sure what the deal with the plastic is. I don't see water leaching through plastic, but I've seen that warning a couple of times.

[Matt Romanowski]

IMHO the Valvoline is better than the ATE or other common ones (from my experience). I would flush the system with fresh fluid within two weeks of the event and have fun!

[SLITS]

In general:

You will not "fry your calipers", you may boil your fluid.

Ahhhh, ever seen a set of brakes on fire? Firebird Raceway .... got so hot, it blew the seals on the front calipers and caught fire ..... it was an awesome sight as the driver blew past the pits! (IMG:style_emoticons/default/sad.gif)

[So.Cal.914]

I'm not sure what the deal with the plastic is. I don't see water leaching through plastic, but I've seen that warning a couple of times.

Plastic will absorb water, thermal injection molding companys have ovens

to evaporate the water from raw plastic pellets before they are placed in the

hopper.

[Matt Meyer]

In general:

You will not "fry your calipers", you may boil your fluid.

Ahhhh, ever seen a set of brakes on fire? Firebird Raceway .... got so hot, it blew the seals on the front calipers and caught fire ..... it was an awesome sight as the driver blew past the pits! (IMG:style_emoticons/default/sad.gif)

I bet it was an awesome sight. But the cause of the fire was not that they used brake fluid rated at 503F instead of 536F or that the fluid was one year old. And I'll bet you a hose from a Ferrari that his fluid was boiling. (IMG:style_emoticons/default/av-943.gif)

No magnesium calpiers I am aware of. I'm guessing the fluid boiled first, burst the seals and then the boiling brake fluid is what actually burnt. WOW!!! That would be an awsome sight indeed.

I am not doubting you but the heat input would either have to be from a mechanical failure/problem or very fast. Once the fluid starts boiling you quit generating heat, as I am sure you are aware.

And water will leach through plastic apparently too. So brake fluid will "suck" water right out of the air and through a plastic container.

And as long as we are pointing out where my previous post was wrong. If you are not flushing your brake fluid every couple of years, Wet BP is probably the important number.

[Matt Romanowski]

I'm not near a container of brake fluid, but water won't go through all plastics. I think they HDPE, which is an excellent moisture barrier. I wouldn't get uptite about unopened plastic bottles.

[SGB]

Thanks all. I'll prolly flush & refill with the valvoline synthetic right before i go, and make sure I have a small enough wrench for my speed bleeders.

[Dave_Darling]

My experience: 6-month old Super Blue. Boiled the living heck out of it at the track; it would last me 15-18 minutes of the 20-minute run session. Had pads with about 60% material left when I started the three-day weekend; a fellow 914'er was nice enough to give me some 50% pads for the third day because mine were down to less than 30% after two days.

Dan is quite right about rookies overusing the brakes.

--DD

[jhadler]

I agree with Dan and Dave.

Brake fluid will absorb water from any source it can. When it does, the boiling point drops. In some fluids, the difference is dramatic. Where you are (high humidity), anticipate that the fluid will start absorbing water as soon as you crack open the bottle. Maybe not a lot, but 1 year old fluid? I'd consider it contaminated with water, with the corresponding wet boiling point.

I used to flush with alternating fluids. Ate Super Blue and Motul 600. The ATE is blue, the Motul is yellow. The practical upshot is you really know when you've flushed out all the old fluid.

Go to a race, and you'll often see people bleeding the brakes between sessions.

Speedbleeders are a nice thing...

-Josh2