Spongy brakes - 1991 300E - Page 3 - PeachParts Mercedes-Benz Forum

Stretch · #31 03-03-2016, 01:09 PM

Quote:

Originally Posted by Hirnbeiss

Screaming at employees is never an effective management technique - long term anyway.

Oh I don't know - works in the army!

mbzr4ever · #32 03-14-2016, 10:17 PM

Broke down and got a power bleeder, completed job in no time.
Hardest part was taking the wheels off and on.

Pedal feels firm - do I need to bleed the abs unit?
(I do need to find some bleed valve caps - 3 of them were missing.)

While I had the wheels off, I looked at the pads and saw the rear ones at about 1/8 inch; front ones were thicker.
I tried to change the rear ones (had new ones ready), but they were too thick to place in between the boot and the rotor.

Any tricks to opening up the space to get the new pad in place?

Stretch · #33 03-17-2016, 03:52 AM

No space as in "I couldn't push the piston back" or "there's one heck of a lot of rust in there and they won't slide in"?

mbzr4ever · #34 03-17-2016, 12:18 PM

Drove the car yesterday, brakes felt perfect!
Thanks to everyone here for your help!

Quote:

No space as in "I couldn't push the piston back" or "there's one heck of a lot of rust in there and they won't slide in"?

Couldn't push the piston back. Found these instructrions:
Mercedes-Benz W124 Rear Brake Pad Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article
Didn't want to undo the brake bleed I had just finished, and thought I should research it some more, buy some brake hoses and schedule another attempt in a few weeks.

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Stretch · #35 03-18-2016, 06:43 AM

Quote:

Originally Posted by mbzr4ever

Drove the car yesterday, brakes felt perfect!
Thanks to everyone here for your help!

Couldn't push the piston back. Didn't want to undo the brake bleed I had just finished, and thought I should research it some more, buy some brake hoses and schedule another attempt in a few weeks.

Attachment 135363

Well keep an eye on it you might find that one of the pistons is stuck. In which case there might be surface rust on one side of the disk but not on the other.

You should be able to push the piston in and not mess up the bleed as you say. Best to remove the master cylinder fill cap and put some rags around it just in case you push fluid out of the reservoir (quite unlikely if you are doing this for a single rear caliper though).

mbzr4ever · #36 04-05-2016, 02:40 AM

Quote:

Originally Posted by Stretch

Well keep an eye on it you might find that one of the pistons is stuck. In which case there might be surface rust on one side of the disk but not on the other.

You should be able to push the piston in and not mess up the bleed as you say. Best to remove the master cylinder fill cap and put some rags around it just in case you push fluid out of the reservoir (quite unlikely if you are doing this for a single rear caliper though).

Decided to replace the brake hoses at the same time the pads will be replaced.
I'm guessing with the brake lines off, the pressure will be off the pistons and it will be easier to replace the pads, correct?

Stretch · #37 04-05-2016, 05:29 AM

Let's hope so.

Duke2.6 · #38 04-05-2016, 10:23 AM

It's easy to push the pistons back with a putty knife or similar tool. Attach a hose from the the bleed valve into a container, open the valve about a half turn, and push back the piston.

On the rear replace one pad at a time. If you try to push one piston back with no pad on the opposite side, it may push the opposite piston out of the bore.

Duke

mbzr4ever · #39 04-06-2016, 12:19 PM

Quote:

Originally Posted by Duke2.6

It's easy to push the pistons back with a putty knife or similar tool. Attach a hose from the the bleed valve into a container, open the valve about a half turn, and push back the piston.

On the rear replace one pad at a time. If you try to push one piston back with no pad on the opposite side, it may push the opposite piston out of the bore.

Duke

Would removing the brake lines, replacing the pads (one side at a time as you suggest), then installing the new lines in that order cause any potential problems?

That is my plan to minimize pressure on the pistons so the new fatter pads can go in easier.

Duke2.6 · #40 04-06-2016, 12:31 PM

Since you plan on replacing the brake hoses along with the pads, removing them will allow easy pushback of the pistons to replace the pads. When changing just pads use the method I recommended in post #38.

However, you will probably loose less fluid making the system easier to bleed if you change the pads first and then change the hoses as quickly as possible... maybe even pinch them with a c-clamp near the caliper, which will at least make the job less messy.

On the front floating caliper design, I can usually push the pistons back with my thumbs after releasing the bleed valve.

Duke

mbzr4ever · #41 01-21-2017, 08:04 PM

Quote:

Originally Posted by Duke2.6

Since you plan on replacing the brake hoses along with the pads, removing them will allow easy pushback of the pistons to replace the pads. When changing just pads use the method I recommended in post #38.

However, you will probably loose less fluid making the system easier to bleed if you change the pads first and then change the hoses as quickly as possible... maybe even pinch them with a c-clamp near the caliper, which will at least make the job less messy.

On the front floating caliper design, I can usually push the pistons back with my thumbs after releasing the bleed valve.

Duke

Hi Duke,

Just to follow up, I wound up replacing with rebuilt calipers, changed hoses and pads. Bought a bleeder pump to make the job easier...now they are perfect, even almost a year later!