First, you'll need some quality fluid. I don't know what the Audi OEM stuff is, but it's fine for everyday driving. If you take your car to the track or just generally drive it hard, here are some good quality brands that have higher boiling points:
- ATE Super Blue, ATE TYP 200 (amber) -- Both fluids are the same, just different colors, so if you alternate between the two, you can tell when the new fluid makes it to each bleed screw
- Castrol GT-LMA
- Pentosin DOT 4 -- This is NOT Pentosin hydraulic fluid!
- Wilwood DOT 4
- Cartel DOT 4
- Ford Heavy-Duty Brake fluid (DOT 3, but apparently very good)
Cars with ABS require a specific sequence; this is:
- Brake master cylinder, then proportioning valve
- Right rear
- Left rear
- Right front
- Left front
- Clutch slave cylinder?? (below steering rack on top of transmission)
- You can build a simple power bleeder with a spare brake fluid reservoir cap and a tire valve. Drill a hole in the center of the cap just big enough for the valve, and seal the valve on it with some RTV sealant. Drain the reservoir with a turkey baster and refill with new fluid. Now just put the cap on and attach a source of LOW pressure (< 15 psi) to the valve and start opening your bleeder screws. NO more than 15psi or the seals below the reservoir will start to leak on you, esp. if you've never replaced them. (They are cheap, but a PITA to replace.) Make sure you keep and eye on the fluid level in the reservoir and refill it when it gets low. If you don't keep it filled, you'll get air in the lines, and you'll have to start all over again.
- If you don't bleed the master cylinder first, you will never be able to bleed all the wheel cylinders.
- Also, the book says if you have "height sensitive brake pressure regulator", press regulator lever firmly towards rear axle when bleeding rear brakes. The height proportioning valve sits on the rear trailing arm on the left side of the car. Jack the car up, locate the valve and insert a 6mm drill bit between the lower spring hook and the roller to fool the valve into thinking that the car is fully loaded so it will bias the brake pressure evenly front to rear. The valve either works or it doesn't. If it's frozen or the spring is missing (broken) nothing happens there. It's expensive, and given what it does, not an absolute critical item. But you should have rear brakes of some sort, even if the valve is broken. It operates in a narrow percentage band of rear bias, never shutting off the rear or the fronts totally.
- Remember, NO PENTOSIN hydraulic fluid in the brake lines! Use DOT4 BRAKE FLUID ONLY. Pentosin is found in the power steering, the brake MC BOOSTER, and the BOMB (brake pressure accumulator, separate from brake fluid). Brake fluid goes into the brake MC reservoir (no need to pull screen) near center of the car; the Pentosin reservoir is on the left fender.
