Milor

Hi all,

RE: 2010 W212 E250 CGI Sedan

Dramas never stop with this bloody car. Pads finally wore out after 95000km. Discs were still over the minimum thickness and very smooth and straight, so I decided to replace the pads only. The discs do have a bit of a lip. Used Brembo pads. Noticed that pads were dragging a lot. Slowing down my car, gears holding longer, increased fuel consumption. I have noticed that rear wheels were affected more than front ones. Noticed that pads were just a tiny bit bigger than the original ones, so the pads were "biting" into the lip on the disc. I suspected that pads were getting "jammed" between the inner and outer lips and not releasing properly. Then I took off all the pads and filed off the edge of the pads, so they don't touch the lips. Problem fixed, but it probably would have reappeared once the pads get worn down a bit and then they would get stuck on the lips again. Not worth machining the discs as new ones are not that expensive.

Therefore I decided to replace the discs and pads. New Brembo discs and pads (new set of pads). Now, the bloody pads seems to be dragging again. Rear ones. Not as bad as the first time, but I can notice it. Discs and pads have been installed with a lot of attention to ensure that guides are greased and everthing runs smoothly.
Any ideas why would this be happening, please?
Silly question: Maybe the car's computer needs to be "reprogrammed" .. to be "told" that new pads and discs are installed?

Thanks
Milo

Mud

I've not seen that the computer needs to be programmed for new pads.
I'm glad you replaced the rotors, to be honest your first fix about the rotor ridges sounded kind of questionable.

Some thoughts:
Are you 100% sure the pads are correct for your car? I've fallen victim before to subtle changes in parts between models. Are the brembo pads designed to work with that rotor thickness? The common denominator for the dragging pads seems to be the pads since this is happening at more than one wheel.

Were shims provided with the new pads? Maybe they are not needed in your application and are adding to the overall pad thickness.

Did you bleed the brakes? The brake fluid in the calipers doesn't move around much, so over miles and years it accumulates debris. Could be the caliper piston is not retracting fully but this seems to be at all wheels. Perhaps more of a maintenance item. New pads should not touch but barely skim over the rotor surface. Anytime brake work is done the fluid should be bled. When you compress the caliper piston to install new pads, open the bleeder to allow that old fluid to be released instead of being pushed back into the system. Personally I flush the brake system every 40k miles or so.

Milor

Yes, I did replace the brake fluid at the same time as I replaced the pads. Disc and pad size is correct. After installing them, I grabbed the caliper with pads in it and moved it in out, sliding it on guides. Plenty of room between discs and pads.

Arrie

Milor

Took it all apart again and noticed that the pins are not moving smoothly. When I remove the bolts holding the caliper and try to move the pins in and out with two fingers, I find a huge amount of resistance at first. After moving the pin both ways a few times, it becomes easier to move. I leave it alone for half a minute or so, try to move the pin again, I find it so hard to move at first, then it becomes a little easier again.
Is that normal resistance of moving the pin through the rubber "sleeve"? It's greased very well with CRC Sta-Lube:

https://www.repco.com.au/en/brands/c...71g/p/A7747144

How freely should the pin move?