Just curious. Am going to do more autocross and the instructor said it is important to remember to flush and top off brake fluid so they don't fade as much. How often are you supposed to do this?

 

I would do mine, every one to two track days depending on how hard I was on the brakes. I do a short track with a lot of hard braking, and I do it after every day, on the longer tracks I do it every two days (unless I do a lot of laps).

I agree with your instructor, flush the fluid often, it is easy to do, and is cheap insurance.

 

thx northvan. Just out of curiosity what do I need to do it? Just a jack and a pan?

 

You need a pressure bleeder, bleed bottle and a line wrench (9mm I think?).

The key to the brakes is NOT to introduce air into the system. They sell one-man pressure bleeder kits, it's a bottle with a cap that screws onto your brake fluid reservoir. You pressurize the bottle (not to high, keep it around/under 10psi), and then you go to each bleed screw (two per caliper) and loosen (do not remove) and the fluid will flow into your bleed bottle (has a hose you put on the bleed screw). The line wrench is for the bleed screw. Do not overtighten either. Small screws don't need crazy torque to tighten them.

If you don't have the one-man bleeder, you can use the pedal and friend, have your friend pump the brakes (car off) about 3 times till the pedal is tight, friend keeps pressure on the pedal, you loosen the bleed screw, fluid comes out, his foot goes to the floor, you tighten the bleed screw, he lifts up and repeats the process (typically 5 times or so per bleed screw).

Either way, NEVER let the brake fluid get below the low line as this can introduce air into the system, and that's the whole point of bleeding the brakes (including replacing old fluid, though I think unless you are tracking once or twice a month, then you can swap fluid once per year.

Start from the furthest corner from the reservoir, and work you way to the closest corner. the dealers have pumps that push new fluid in, so they can do it a lot faster then the home person. Be careful with brake fluid as well, it'll eat through most everything, so don't spill it and if you do, clean it quick.

 

Got my brake fluid checked and okayed by the dealer in October 2008. Since then had two track days and will go track for two more days this weekend. Do you think I need to have my brakes flushed?

 

What is the purpose of flushing the fluid as opposed to just adding more when it gets low?

 

How many miles/track events on the current fluid in your car? For me, once a year assuming less then 3 track events. If I was doing 12 track events a year, I'd probably replace the fluid semi-annually.

You are probably fine, take a look at the reservoir and make sure the fluid looks clean, if it's dark or cloudy, probably flush it. Unless you are running Castrol SRF, brake fluid is cheap.

 

Around 8K miles and 3 days of track (5 after this weekend). I'll check the fluids again, but when I checked in November, it looked pretty clean.

 

I look at as the cheapest thing you can do to avoid a bad day at the track. A buddy of mine in his 997C2S was coming down the front straight of a local track and lost brakes due to overheated fluid. He managed to get the car to the pits, but it scared the $hit out of him.

I figure that it doesn't hurt to replace it, and it is about 30 minutes extra when changing the to the track tires.

 

The fluid really shouldn't just "reduce" like oil can burn off. Brakes are a sealed system and the fluid is pretty stout.

But as you use brake fluid (heat it up and cool it down like on track events) and just over time, the water content in the fluid increases (the exact opposite of what brake fluid wants to be). The problem is water turns into vapor when you boil it. Air is compressible, and so air inside your brake system is what makes the pedal "mushy/soft" or in bad examples, just go right to the floor.

Brake fluid has a shelf life, so keeping fresh fluid in the car, and keeping the brakes bled (no air in the system) means you are getting the most of the brakes, and when heading to the track, you want to make sure your brakes are a "known" (pad depth, rotor condition, brake fluid condition and the last brake bleed).

But to your original question, you want to keep the brake fluid above the low line to keep air from getting into the system.

 

As Ryan said you need a pressure bleeder, very easy to use.

This is what I use

http://store.motiveproducts.com/shar...unt2=570014595

The first time takes a little bit more time getting yourself familiar, but after that it is fast and easy.

Just remember, brake fluid will kill your paint, so don't let it get on your car.

 

Once a year before DE season. I only do a few DE events.

 

We flush brakes before every event. Too cheap and easy to not do. Brakes are the one thing you have to have working at their best. I know guys that flush at the beginning of the season, and that is it, but I don't like to play that game.

I use Motul and ATE Superblue.

 

Brake fluid gets HOT at the track and boils and creates air in the brake system. So you need to flush the brakes after each event. I changed out my stock fluid as soon as I got my car and put in Motul600. I will flush each event and then change....flush flush through....after 2 events.

 

Guys, you all need to read up on brake fluid a bit. It's not the number of events you put on fresh fluid, it's a time issue. Most PCA chapters will not tech approve you unless the fluid is 2months old or newer. Read up on Wet vs. Dry boiling points. Basically, brake fluid takes on moisture over time - not so much use (though hard use will accelerate the issue). So the boiling point of the fluid declines over time (wet BP). When fluid is new, it's all pretty good and up to the test. Never use Blue, always use ATE 200 / Gold and even better would be Motul Those are all suseptible to getting "wet" and losing boiling point. Want to use just 1 fluid for a whole season? Then invest in Castrol SRF. It's magic fluid and the wet BP is almost equal to the dry, and both are at or above the others even when they are dry. That's why it's $75 a bottle. But, spend that once in the spring and it will last all year.

You are taking a $100k car on the track, so don't cheap out on perhaps the most important component on the car - the brakes that run on brake fluid. I spend about $150 a year on SRF - $75 for the fluid and $75 for the labor to have it professionally done (and I don't have to buy a bleeder, figure out where to legally dispose of the fluid, or take up an hour of my time doing it myself).