Calipers, master cylinders, flushes, Oh My! - PeachParts Mercedes-Benz Forum

phidauex · #1 11-25-2005, 01:34 PM

Hi again,

Soon I'll be doing some major brake work. I've got a slight leak in my master cylinder (symptom, brake pedal slowly falls toward the floor under medium-hard pressure, restores brake feel after 'pumping'), my rear calipers need to be rebuilt (I'm going to try this out myself, I've got the rebuild kit for both sides), I'll be installing new rear hoses, and flushing the system as well.

My question is... What order should this all happen?

I'm thinking:

Remove calipers and hoses, plug the line
Rebuild the calipers
Reinstall the calipers and new hoses
Flush the system with new fluid
Bench bleed the new master cylinder with new fluid
Install the new master cylinder
Bleed the system

My thought is that it would be good to flush before adding the new master cylinder, to prevent old fluid from getting into the new cylinder. However, that concern may not be warranted, and I might be about to cause myself more headache than necessary. Should I flush as the last step, maybe?

And finally, I may be forced to move the car down the block to a parking lot to work on it, and then I may have to move it back to its parking spot before I'm done rebuilding the calpiers, if I run into trouble with the rebuild process. Is it possible to drive the car using just the emergency brake? I'm thinking I'd use one hand to steer, and one to pull back the brake release plunger. Then one foot would drive, and the other would work the emergency brake pedal. I know this sounds terrible, but it would only be to get it up the block and around the corner at super low speeds. Is there some fundemental mechanical reason that I couldn't do that?

peace,
sam

Stevo · #2 11-25-2005, 05:41 PM

I did some major brake work on a 240D last summer and I just drained the system (Pressure bleeder) and flushed it with new Dot 4, did all my work then filled the M/S and hooked up the pressure bleeder. It took alot of bleeding (three times around) but with the pressure bleeder, no big deal. If you dont have one, I 'd consider investing the $ as they are really slick.
As to your trip using the E brake, those little drums wont stop you very well, better get ready to drag your feet

OMEGAMAN · #3 11-25-2005, 05:54 PM

If you need to drive the car with the rear calipers off just clamp the line off with a pair of vice grips and you just wont have rear brakes. You probably shouldnt do this with your new hoses but the old ones who cares. When you have replaced and rebuilt all your going to do then just flush the brake fluid by pumping. You should be able to gravity bleed all your calipers to remove the old stuff and then a few quick foot pumps to remove any air in the system