Brake Master Cylinder Replacement - PeachParts Mercedes-Benz Forum

jcd · #1 05-20-2002, 07:55 AM

My master cylinder is on the way out. I have read a number of posts on this topic. Looks pretty straightforward and I have read the tips on replacing the rubber mounts for the resevior and the o-ring where the MC fits to the vacuum booster.

Question: How long does this job take and are their any tips.

JCD

luvmysd · #2 05-20-2002, 08:01 AM

Hi, it took me about 45min including bench bleeding it. One the nuts holding it to the booster ( the one towards the center of the car) was hard to get to but a gear wrench made it a lot easier.

jcd · #3 05-20-2002, 08:59 AM

I noticed on Fastlane they had a brake master cylinder repair kit. Anyone had experience with this. it is 1/2 the cost of my brake master cylinder.

JCD

peterhardie · #4 05-20-2002, 09:57 AM

I have rebuilt master cylinders and have replaced them. Either way can produce satisfactory results, and so the equation involves $$$ and your time, and somewhat the condition of the old master, which cannot have excessive corrosion inside and be successfully repaired. Technically, you should hone the inside to make a smooth bore. In some cases, using a scotchbrite pad rolled up, I have been able to touch up a borderline (no pitting) master. I always worry about changing the inside diameter of the casting.

It ain't rocket science. Most kits include your seals, new springs, and sometimes all the other metal parts that make up the working guts of the master. Watch the order everything comes apart (there is stiff spring pressure, so be careful not to have the innards fly out willy-nilly), and do the same in reverse with the new stuff. Inspect your bore visually and check with a paper clip or similar whether there is pitting.

If you have the time, take the whole shebang apart before you order anything. If your bore is shot, just get the new one. If this is your first time, and you might have other brake system issues, get a new master. you don't want to worry about whether some ongoing problem is your rebuild or something else.

Rebuilding may add an hour to an r&r. Good luck.

Peter

jcd · #5 05-20-2002, 10:03 AM

I'm just going to order a new one. The car is my daily driver and I don't want to mess around with soft brakes.

Thx for the quick response. This site is great.

JCD