Weird Brake Problem (Follow up to "Spongy Brakes")
 

Hey Gang,

Well, I went on to "Step Two" which was bleeding the brakes.

It was something I have never encountered. The first one I did was the
right rear: Nothing came out. I had my SO pumping the brakes 5 times, hold.
Nothing. Finally, I got a VERY LITTLE dribble of fluid to come out. But
that isn't right.

Move to the left rear. The fluid SHOOTS out great. After a few more times,
move up to the front right. Fluid SHOOTS out great.

Get to the front Left...Nothing. NEVER a DRIBBLE of fluid.

The pedal goes all the way to the floor. I backed down the driveway to see
how it would stop...I could slam on the brake pedal and it would still move
another few feet before resting.

Obviously, the left front and the right rear aren't getting the
juice/pressure they need. What would this be? Is this for certain Master
Cylinder?

Thanks gang,

ER

"EggRaid" > wrote
> It was something I have never encountered. The first one I did was the
> right rear: Nothing came out. I had my SO pumping the brakes 5 times,
> hold.
> Nothing. Finally, I got a VERY LITTLE dribble of fluid to come out. But
> that isn't right.
>
> Move to the left rear. The fluid SHOOTS out great. After a few more
> times,
> move up to the front right. Fluid SHOOTS out great.
>
> Get to the front Left...Nothing. NEVER a DRIBBLE of fluid.
>
> The pedal goes all the way to the floor. I backed down the driveway to
> see
> how it would stop...I could slam on the brake pedal and it would still
> move
> another few feet before resting.
>
> Obviously, the left front and the right rear aren't getting the
> juice/pressure they need. What would this be? Is this for certain Master
> Cylinder?

Almost certainly the MC. BMW (and almost every automaker) use a
dual-diagonal system, so that if one brake circuit fails, you have a
semblance of balance left-right.

New MC time - I do not recommend rebuilding one.

Floyd

On Thu, 16 Dec 2004 05:17:02 +0000, EggRaid wrote:

> Thanks All. I looked through the bentley's and it doesn't seem like too
> tough of a job on the 1993 740i. The part looks to be about $200US. Any
> comments regarding a first-timer doing this task?

It isn't a difficult job. Just take care to clean the lines well where
they connect to the Master Cylinder before removing the old unit to keep
from introducing dirt into the circuits. I always leave the brake lines
loose at the master cylinder until I've worked all of the air out of the
new unit. That saves quite a bit of time when bleeding since you don't
have to push as much air all the way through the system and out the
calipers. Be sure to wash off and brake fluid the gets on painted parts,
it can take the paint off if left for a while.

--
The instructions said to use Windows 98 or better, so I installed RedHat.

EggRaid wrote:

<snip>

> Thanks All. I looked through the bentley's and it doesn't seem like too
> tough of a job on the 1993 740i. The part looks to be about $200US. Any
> comments regarding a first-timer doing this task?

The brake line fittings at the MC are very soft, and will be damaged
easily if you try unscrewing them with a regular wrench. A flare nut
wrench is an absolute necessity. Don't ask me how I know :-(