How much of fluid needed to bleed brakes?

[Audi-RS6]

Have few questions:

- How much fluid should I buy to completely bleed brakes?
- Do we bleed X way?
- and which side should I start?

Thanks ppl
Vi

[KfabR8]

Not sure how much - purchase at least a quart.

Once the seal's been broken, the stuff will start to suck in moisture from the surrounding air, even if the caps on fairly tight. Brake fluid (other than DOT5 - silicone) loves to suck moisture out of the air and this lowers the boiling point dramatically. Put the cap on any time you're not pouring and don't do this if it's humid or raining. The lower the humidity the better.

Once you're done, it's probably best to keep the bottle for a couple of weeks, check the level of the fluid and if it needs more add, if not, toss the fluid. An open container's shelf life is limited.

While this may sound a bit wasteful, it's a safety issue and your life's not worth the few bucks you may toss at the end of the day because you've introduced moisture into your braking system with old "wet" fluid.

DO NOT USE DOT5! It will NOT play nice with the other DOT fluids and will cause major issues.

I've always had great results with Wilwood's brake fluids (http://www.wilwood.com/BrakeFluid.aspx) - been using the 570 in my desert race car for years.

Be VERY careful not to drip any fluid on anything painted. It will destroy the paint, quite quickly.

If possible, jack all four corners off the ground, keeping the car as level as possible.

Remove the wheels.

To bleed you system, start out in the back (longest lines).
Open the master cylinder's res, fill the res to the top.

Go to either of the rear calipers (I'd go to the passenger's side as this line is probably longer just a touch than the driver's side), find a piece of clear hose that will fit snugly over the bleeder valve's nipple. Make sure this hose is about 2 feet long, put it on the bleeder's nipple, drop the line down and put a small loop in the hose about half way down it's length.

Put the free end in the top of a small bottle - make sure the end of the hose is at the bottom of the bottle, is not flat against the bottom.

Go get a beer and a chair. If you really want to do this correctly plan on taking your time.

Crack open the bleeder valve. You only need to open it about 1/2 of a turn. Do NOT over tighten the bleeder when you snug it back down. They don't need to be ham-fisted, just snug. The bottom of the bleeder is a conical seat and doesn't take much force to seal off.

Fluid should slowly start draining out of the hose. You may have to pump the brake pedal SLOWLY once or twice to get the fluid flowing. You'll need help here - close the bleeder valve, have someone push the pedal, open the valve. The pedal should go to the floor and the fluid should start flowing. Close the valve, release the pedal and then open the valve again.

When pumping, put the cap on the res - not tight, just on top. As you pump there's a good chance that you'll get a little geyser of fluid in the res.

Let the fluid flow. Keep a very close eye on the res - if you let the level drop and it has a chance to suck air, you'll be very busy and in for a fun day of bleeding.

Watch the fluid that's coming out of the caliper. It will change color. The older fluid will, more than likely, be a grayish or brownish color and probably slightly murky. Once you get nothing but clear, clean fluid coming out of the caliper, close the valve (remember - not tight! - just snug).

Move over to the other rear corner and repeat.

Figure out which line up front is the longest (should be the passenger's side again), repeat and then finally do the other front corner.

By letting gravity and flow replace the fluid, you get a better, cleaner replacement of fluid, you minimize the chance of inducing air into the system (keep an eye on the level in the res!) and you'll get the best results.

The gravity method does take patience.

You can cheat and use the pedal to pump fluid through, but that takes two people and good timing.

If you go this way make sure you two communicate:
Person 1 "Pedal pushed."
Person 2 "Valve open."
Person 1 should experience the pedal going to the floor and should make a comment such as "Down".
Person 2 "Valve closed."
Person 1 "Pedal released."

Repeat until clear fluid is all that escapes through the hose.

WATCH THE RES LEVEL!!! <--- can't stress this enough.

[KfabR8]

quick addition:
I can't recall if the RS6's calipers have two bleeders or not. If they do, bleed the side that the brake line attaches to first, then move to the opposite bleeder.

[hahnmgh63]

I highly recommend a pressure bleeder like the Motul one, they are around $50 and have a pressure gauge built into them and will last for years. Just order it initially with the VW/Audi/Porsche attachment and don't go over 20 psi. I usually restrict myself to 15psi. A tech from Brembo once told me that the old fashion method of pumping the brake pedal quickly wears out your Master Cylinder as it causes the piston to travel farther than it normally does and this part of the cylinder gets rough and sometimes corroded in a fairly short time. Every master cylinder I've seen apart has confirmed this so he sold me. Skip the vacuum bleeders too, go for pressure bleeding. Remember, it is always better to Blow than Suck :)

[snoopra]

I second the pressure bleeder. I use ATE super blue racing fluid (DOT4).
The front calipers has two bleeders, inner and outer.
REMEBER! Brake fluid = paint remover!

[snoopra]

Have few questions:

- How much fluid should I buy to completely bleed brakes?

Thanks ppl
Vi
I used about 1.5L.

[DHall1]

Ok,

Good thread as it is time to bleed my car.

I have some of the blue DOT4 fluid listed below...has anyone else used this on the RS6?

As for bleeders....I have one of those Motul units....does anyone have a link or picture of VW attachment? I will google it as well.

What about the ABS? Dont we need to flush it as well?




I highly recommend a pressure bleeder like the Motul one, they are around $50 and have a pressure gauge built into them and will last for years. Just order it initially with the VW/Audi/Porsche attachment and don't go over 20 psi. I usually restrict myself to 15psi. A tech from Brembo once told me that the old fashion method of pumping the brake pedal quickly wears out your Master Cylinder as it causes the piston to travel farther than it normally does and this part of the cylinder gets rough and sometimes corroded in a fairly short time. Every master cylinder I've seen apart has confirmed this so he sold me. Skip the vacuum bleeders too, go for pressure bleeding. Remember, it is always better to Blow than Suck :)

[terrytcl]

yeah, there's a vagcom sequence for the ABS system you'll need to flush the ABS pump.

don't forget to do that.

i use the blue brake fluid ATE Race... no problems... great stuff as you can clearly see when the old stuff has flushed out of the lines and when you're low or high in the reserviour