Mercedes-Benz Parts Catalog Mercedes-Benz Accessories Catalog Mercedes-Benz Technical Articles Mercedes-Benz Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Front Brake Pad Replacement
 
Bookmark and Share

Pelican Technical Article:

Front Brake Pad Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$25 to $55

Talent:

**

Tools:

Punch, hammer, pliers, flathead screwdriver

Applicable Models:

Mercedes-Benz W123 (1977-85)

Parts Required:

New pads

Hot Tip:

Clean the caliper mounting surfaces

Performance Gain:

Car stops better

Complementary Modification:

Replace Rotor or disk

In general, you should inspect your brake pads about every 25,000 miles or once a year, whichever is less, 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 or hear a squeaking noise when they apply their brakes.

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 if you have drilled or slotted rotors there is no way to repair them. The smart thing to do is to avoid this problem and replace at the correct times.

Safely jack up and support the front of the vehicle and remove the front wheels. Please see our article on safely lifting and supporting your Mercedes W123.

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 front brakes on the W123 are a dual piston caliper and both pads (red arrows) can be replaced without removing the caliper.
Figure 1

The front brakes on the W123 are a dual piston caliper and both pads (red arrows) can be replaced without removing the caliper.

To change out the pads begin by removing the brake pad wear sensors from the holder on the side caliper by pulling them (red arrows) straight out.
Figure 2

To change out the pads begin by removing the brake pad wear sensors from the holder on the side caliper by pulling them (red arrows) straight out.

You should be able to pull them 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.
Figure 3

You should be able to pull them 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.

Use the appropriate sized punch and tap out the retaining pins (red arrows).
Figure 4

Use the appropriate sized punch and tap out the retaining pins (red arrows). If you don't have a punch you can use a small screwdriver in a pinch. The retaining pins will probably be covered in brake dust so make sure to clean them before reinstalling.

Keep pressure on the retaining spring while removing the pins and then remove the spring (red arrow).
Figure 5

Keep pressure on the retaining spring while removing the pins and then remove the spring (red arrow).

Depending on how worn your rotors and pads are you will need to compress the pistons back into the caliper.
Figure 6

Depending on how worn your rotors and pads are you will need to compress the pistons back into the caliper. Use a large set of pliers or channel locks and squeeze the pads and the flat area of the caliper (red arrows).

While you are pushing the piston back in you will be forcing brake fluid back into the system and up into the reservoir.
Figure 7

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 (red arrow) in the reservoir as you do this and be prepared to remove some fluid as needed.

Use a flathead screwdriver and pry the pads out from the caliper; if they have anti squeal pads on the back they will stick in there pretty good.
Figure 8

Use a flathead screwdriver and pry the pads out from the caliper; if they have anti squeal pads on the back they will stick in there pretty good.

You will need to push the piston all the way back into the caliper to install new pads so before you remove the old pad use the pliers to compress the pistons all the way in remembering to check the level of fluid in the reservoir.
Figure 9

You will need to push the piston all the way back into the caliper to install new pads so before you remove the old pad use the pliers to compress the pistons all the way in remembering to check the level of fluid in the reservoir. You also want to clean up the area where the pads rest against the caliper (red arrows), this area gets a lot of brake dust on it and that can lead to squealing brakes.

This photo shows the hole that the brake wear sensor sits in (red arrow) and while there is plenty of material still on this pad is it wears down to this hole the wear sensor cover will wear off and make contact with the rotor, this will cause a ground and sends an electrical signal to light the wear light in the dash.
Figure 10

This photo shows the hole that the brake wear sensor sits in (red arrow) and while there is plenty of material still on this pad is it wears down to this hole the wear sensor cover will wear off and make contact with the rotor, this will cause a ground and sends an electrical signal to light the wear light in the dash.

If you are changing your pads before the wear sensor has activated there is no reason why you cannot reuse it but if the coating (red arrow) has worn down you should replace it.
Figure 11

If you are changing your pads before the wear sensor has activated there is no reason why you cannot reuse it but if the coating (red arrow) has worn down you should replace it. Installation is the reverse of removal.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Fri 12/9/2016 03:04:08 AM