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Rear Brake Pad Replacement
 
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Pelican Technical Article:

Rear Brake Pad Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$40 to $200

Talent:

**

Tools:

7mm Allen, pliers C-clamp, floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

Mercedes-Benz C250 (2012-14)
Mercedes-Benz C300 (2008-14)
Mercedes-Benz C350 (2008-14)

Parts Required:

New pads

Hot Tip:

Clean and lube the slider bolts

Performance Gain:

Car stops better

Complementary Modification:

Replace Rotor or disk

Replacing your brake pads is one of the easiest jobs to perform on your Mercedes. In general, you should inspect your brake pads about every 25,000 miles, and replace them if the material lining of the pad is worn down enough to trigger the pad replacement sensor or there is less than a quarter-inch of material on the pad. In reality, most people don't inspect their pads very often. They usually wait until they see the little brake-warning lamp appear on the dashboard. It's a wise idea to replace the pads, and inspect your discs at least once a year.

If you let the pads wear down enough you will get to the point of metal on metal contact, where the metal backing of the pads are contacting the brake discs. Using the brakes during this condition will not only give you very dangerous and inadequate braking, but will also begin to wear grooves in your brake discs. Once the discs are grooved, they are damaged, and there is often no way to repair them. Resurfacing will sometimes work, but often the groove cut will be deeper than is allowed by OEM specifications. The smart thing to do is to avoid this problem is to inspect and replace the pads at the correct times.

Safely jack up and support the rear of the vehicle and remove the front wheels. Please see our article on safely lifting and supporting your Mercedes W204.

Brake pads should always be replaced in pairs. If you have not bled your brakes in a while this is a good time to give them a good bleed and get fresh fluid in the system. Please see our article on bleeding your brakes.

The rear brakes on the W204 are a floating caliper.
Figure 1

The rear brakes on the W204 are a floating caliper. This means the caliper is attached to the mount by sliding bolts and has only one piston on one side of the caliper (red arrow). As pressure is applied to the pads by the caliper piston the caliper slides or floats along the slide bolts to transfer the clamping force to the pad on the other side.
.

To change out the pads begin by removing the brake pad wear sensor from the holder on the right side caliper (red arrow).
Figure 2

To change out the pads begin by removing the brake pad wear sensor from the holder on the right side caliper (red arrow).

Pull the wear sensor straight out from the mount on the caliper (red arrow) and then remove it from the pad (yellow arrow).
Figure 3

Pull the wear sensor straight out from the mount on the caliper (red arrow) and then remove it from the pad (yellow arrow). You should be able to pull it from the pad by hand but if it is stuck use a set of small needle nose pliers to remove it, using care if you are planning on reusing the sensor. If you are changing your pads before the wear sensor has activated there is no reason why you cannot reuse it but if it has worn down you should replace it. While it is not necessary to remove the wear sensor housing from the caliper, I like to use an E10 Torx to remove the housing and get it out of the way.

Use a set of pliers and pry the retaining spring out from the front of the caliper (red arrow).
Figure 4

Use a set of pliers and pry the retaining spring out from the front of the caliper (red arrow).

Remove the two protective caps from the slide bolts, and use a 7mm Allen to remove the bolts.
Figure 5

Remove the two protective caps from the slide bolts, and use a 7mm Allen to remove the bolts.

These are the bolts that the caliper slides on (red arrow).
Figure 6

These are the bolts that the caliper slides on (red arrow). They should be smooth and free from any corrosion. Clean up the bolts with a little Emory paper and lubricate them before reinstalling.

Depending on how worn your rotors and pads are you will need to compress the piston back into the caliper.
Figure 7

Depending on how worn your rotors and pads are you will need to compress the piston back into the caliper. Use a large flathead screwdriver and place it between the caliper and rotor, and push the caliper outwards, which will force the piston back in. Never place the screwdriver around the piston, as you can damage it or the rubber boot.

While you are pushing the piston back in you will be forcing brake fluid back into the system and up into the reservoir.
Figure 8

While you are pushing the piston back in you will be forcing brake fluid back into the system and up into the reservoir. Make sure to check the fluid level in the reservoir, as you do this. Be prepared to remove some fluid as needed.

You can now remove the caliper form the mount.
Figure 9

You can now remove the caliper form the mount. Be prepared to hang the caliper or place it on something at a height that will not put any stress on the brake hose or line. Never let the caliper hang from the brake line.

You will need to push the piston all the way back into the caliper to install new pads.
Figure 10

You will need to push the piston all the way back into the caliper to install new pads. Before you remove the old pad, use a large C-clamp and compress the piston all the way in, remembering to check the level of fluid in the reservoir.

The pad on the piston side will come with metal clips that hold it in the position in the caliper and piston.
Figure 11

The pad on the piston side will come with metal clips that hold it in the position in the caliper and piston. Pull the old pad out and press the new pad in. The pads will be marked F for front and R&L for right and left

The outside pad will come with an anti-squeal pad on the back; this is just a sticky material that helps hold the pad in place and prevents squeals.
Figure 12

The outside pad will come with an anti-squeal pad on the back; this is just a sticky material that helps hold the pad in place and prevents squeals. Push the old pad off the caliper, clean up any residue form the old backing and install the new pad. Installation is the reverse of removal. Once everything is back together pump the brake pedal a few times to move the pads into position against the rotor. Always follow the breaking in instruction that will come with your new pads. New pads need to be broken in properly and will have diminished braking capabilities until they are.



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Comments and Suggestions:
Change Mecanico Comments: What are the torque values for the floating pins?
October 28, 2016
  Followup from the Pelican Staff: I don’t have that info.




I would grab a repair manual. It will have the procedure, special tools and torque specs.


Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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