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Pelican Technical Article:

Front Brake Pad Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$65 to $85

Talent:

**

Tools:

Punch, hammer, flathead screwdriver, turkey baster

Applicable Models:

Mercedes-Benz W124 (1986-95)

Parts Required:

New pads

Hot Tip:

Don't damage the dust boots on the pistons

Performance Gain:

Car stops better

Complementary Modification:

Replace Rotor or disc

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, and 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 as soon as you see that warning lamp go on.

If you ignore the warning lamp, you may indeed 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 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 and replace your pads right away.

The brake system on the front of the W124 is a fixed four-piston caliper set. The great thing about the fixed calipers on the car is that you can change the brake pads without removing the rotors, saving you a lot of time and effort. If you do not open any of the brake lines you do not need to bleed the brake system. But if you have not bled the system in over a year this would be a good time to do it. Please see our article on bleeding your brakes for additional help.

PLEASE NOTE: This article is not applicable to 1989 300ce

This photo illustrates the front brakes on the W124.
Figure 1

This photo illustrates the front brakes on the W124. The rotor (red arrow) rotates with the wheel and the caliper (yellow arrow) squeezes the rotor when you apply the brakes.

The nice thing about the calipers is they are fixed and do not need to be removed to change the pads.
Figure 2

The nice thing about the calipers is they are fixed and do not need to be removed to change the pads. The pads can be changed through the opening in the caliper (red arrows).

Remove the two brake wear sensors by gently pulling the sensor end from the pad (red arrow) and then removing the end from the connector on the caliper (yellow arrow).
Figure 3

Remove the two brake wear sensors by gently pulling the sensor end from the pad (red arrow) and then removing the end from the connector on the caliper (yellow arrow). The wires should run under the lip in the spring clip.

Use a small punch and tap out the retaining pins that hold the brake pads in the caliper (red arrows).
Figure 4

Use a small punch and tap out the retaining pins that hold the brake pads in the caliper (red arrows). Once the one end of the pin is free of the caliper push down on the spring clip to help remove it the rest of the way. The new pads may have come with new pins, if they did not clean the old ones up with a Scotch-Brite pad.

With the pins removed take out the brake pad retaining spring clip (red arrow).
Figure 5

With the pins removed take out the brake pad retaining spring clip (red arrow).

On some calipers and pads you can use a screwdriver between the pads and rotor to push the pistons back into the calipers and remove the pads; on this caliper I recommend you use a large wrench or channel locks and squeeze the pads back towards the caliper (red arrows).
Figure 6

On some calipers and pads you can use a screwdriver between the pads and rotor to push the pistons back into the calipers and remove the pads; on this caliper I recommend you use a large wrench or channel locks and squeeze the pads back towards the caliper (red arrows).

When pushing the pistons back into the caliper you will be causing brake fluid to be pushed back up through the system and into the fluid reservoir.
Figure 7

When pushing the pistons back into the caliper you will be causing brake fluid to be pushed back up through the system and into the fluid reservoir. If your reservoir was full you may need to use a turkey baster and remove some fluid (red arrow). Always make sure the area around the cap and the baster are clean before performing this work; you do NOT want to get any contaminants into the brake fluid.

Use a screwdriver and pry the pads out from the caliper (red arrow).
Figure 8

Use a screwdriver and pry the pads out from the caliper (red arrow). If they are old they may be stuck to the pistons.

If you are just inspecting the pads check for any glazing, grooves, uneven wear or missing material.
Figure 9

If you are just inspecting the pads check for any glazing, grooves, uneven wear or missing material. These pads are in good shape with lots of life left (red arrow).

Inspect the inside of the calipers.
Figure 10

Inspect the inside of the calipers. Check for any damage, rust or tears in the dust boots around the pistons (red arrows). Now is a good time to clean up all the old brake dust that will be in this area.

This photo illustrates where the pistons made contact with the backs of the old pads.
Figure 11

This photo illustrates where the pistons made contact with the backs of the old pads. You can also see the anti-squeal (red arrow) that was applied. Some pads will come equipped with anti-squeal backing. It is a good idea to apply a little anti-squeal to the backs of the pads; just make sure not to get any on the actual pad surface. Installation is the reverse of removal. When finished with both sides, press on the brake pedal repeatedly to make sure that the pads and the pistons seat properly. Also make sure that you top off the master cylinder brake fluid reservoir if necessary. Brake pads typically take between 100 and 200 miles to completely break in. It's typical for braking performance to suffer slightly as the pads begin their wear-in period. Make sure that you avoid any heavy braking or emergency maneuvers during this period.






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Comments and Suggestions:
kjohnmc Comments: This was very helpful!

1990 300 CE

Perfect!
July 17, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
johnny Comments: this is also not for my 1989 Mercedes ce 300.
November 4, 2015
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it. I will have the article updated.
- Nick at Pelican Parts
 
mike Comments: This helped me a lot, thank you. However my 1987 w124 does not have any pins, as showed in fig. #4.
February 18, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Jai Comments: Thanks for all the great articles!

Just a little note, this is not for the E280/280E. The E280/280E has another rotor, caliper and brake pads, probably also the same case with the 260E. Maybe more. Regards!
November 10, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it. I will have the article updated.
- Nick at Pelican Parts
 

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