[Jeff@TopGearSolutions]

Originally Posted by feuer

While ATE Racing Blue was available I alternate between Yellow and Blue in preparation for track season and after 1L the brake fluid color will change. My car is 6MT as well. So 2L would be more than sufficient if you ask me.

I used a little over 2 the last flush. Perhaps I was overly conservative with ensuring all the fluid was changed out.

At any rate, buying 3 and having a spare isn't the end of the world. I always keep at least 1 liter of brake fluid available for a rainy day.
What's bad is if you only buy 2 and you needed more.

[juld0zer]

Any 6cyl DSC unit will work. Just swap the valve blocks and you wont have to code the car.

Id suggest fixing it sooner than just putting up with it because when your pedal drops to the floor, you have no more room to push the pedal further. You will have to take your foot off and reapply it. Not good in a panic situation.

[bbnks2]

Originally Posted by juld0zer

Any 6cyl DSC unit will work. Just swap the valve blocks and you wont have to code the car.

Id suggest fixing it sooner than just putting up with it because when your pedal drops to the floor, you have no more room to push the pedal further. You will have to take your foot off and reapply it. Not good in a panic situation.

You're right I'll look into swapping the valves. You definitely think it's dsc? I usually have sac completely off and e-diff is even coded out... does abs use the dsc valves?

[juld0zer]

Same thing. Calling it the ABS module on any late model car these days is a bit old school
All ABS functions are carried out and computed by the same control unit.

Personally I'd revert it back to stock to eliminate software as a possibility but im reasonably confident that a replacement valve block will solve your problem. You will need to remove the whole module from the car to swap either half. Which results in doing a full DSC bleed via INPA or ISTA after you pressure bleed the system. Then reset all the valve calibrations.

That's assuming your pedal doesnt sink under constant foot weight (good master) and your hydraulic connections (union nuts at every connection from master to caliper and nipples are all leak free.

[AD18]

Originally Posted by Jeff@TopGearSolutions

I used a little over 2 the last flush. Perhaps I was overly conservative with ensuring all the fluid was changed out.

At any rate, buying 3 and having a spare isn't the end of the world. I always keep at least 1 liter of brake fluid available for a rainy day.
What's bad is if you only buy 2 and you needed more.

I ordered 3L anyway, so hopefully they won't use it all and I'll have some spare left over.

[AD18]

Just in case anyone comes along wanting to know quantities when changing brake fluid. My indy used 2 litres for a complete flush of the system. Buying 3L is no bad thing as you'll have spare left over, as mentioned above.
Cheers.

[mweisdorfer]

Bentley Repair Manual states you need two people to properly bleed brake lines. One person opens the bleeder screw while the other person pumps 8-10 times and then holds the brake pedal down, after the 10th pump. During the hold, the person pumping the brake pedal should say "hold"; a few seconds after you hear the words "hold", the person near the bleeder screw closes the bleeder screw. You should do this 3x per brake caliper starting with the passenger rear, driver rear, passenger front then driver front, in that order.

Having new bleeder screws helps a lot. Especially if you live in the rust belt part of the country or a state that uses salt on the roads during the winter. A lot of times bleeder screws can get corroded, and the little hole is now even smaller, or in some cases non-existent.

You should never leave/ let the master cylinder to run dry for any real length of time. You will/ could let air into the ABS system, if you do.

Two things can help pedal feel. One, SS brake lines. Stop Tech or Goodridge are probably the two best sets for our cars. Two, brass guide pin bushings. ECS tuning makes the best brass guide pin bushings.

I would agree with the Fuer regarding the ABS system needed to be bleed. The Foxwell scanner or ECS tuning's version of the Foxwell's scanner can also bleed the ABS system. If you plan on long term ownership and DIY's as a part of this long term ownership, a quality scanner with dedicated BMW software on it is an absolute MUST.

[mweisdorfer]

Originally Posted by AD18

Just in case anyone comes along wanting to know quantities when changing brake fluid. My indy used 2 litres for a complete flush of the system. Buying 3L is no bad thing as you'll have spare left over, as mentioned above.
Cheers.

I use 3-4 ten oz bottles.

[pwner4once]

OP, did your issue end up getting resolved?

[Mick Van B]

Originally Posted by rich_mane

I know this is a bit old, but anyone consider the vacuum pump being the source of the problem? I'm starting to have a similar brake pedal problem where it sometimes takes longer to engage than other times. It has that "on/off" feeling someone described, where it's hard to inch forward without the car lurching.

Since this problem is intermittent, it's hard to pinpoint. I have all new brakes and new bmw fluid with a complete flush. But there are times when the pedal feels normal, and it's very easy to modulate the strength of the brakes. I've also noticed that when the brake pedal is acting normally, the motor is more responsive to lighter amounts of throttle, and overall more responsive in general (AND the exhaust burbles from the MHD flash tune are more intense..) Keeping the throttle light, I can actually get the brake pedal to act normally a majority of the time. Jam the throttle a bit more and build boost though, and I start to feel the problems of a slightly spongey brake pedal and slower motor response afterwards.

Just some food for thought. I'm gonna start testing the vacuum system and trying to find a problem. Probably replace all the lines and maybe go for a new pump if nothing changes.

rich_mane - did you manage to resolve your brake pedal issue? I have the exact same thing on my 2012 535xi. Inconsistent brake pedal feel and when good, also better gas pedal response. Was leaning towards vacuum pump also. Best, Mick