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Front Shock Absorber Replacement
 
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Pelican Technical Article:

Front Shock Absorber Replacement

Kerry Jonsson

Time:

6 hours6 hrs

Tab:

$500

Talent:

***

Tools:

13mm, 17mm, 21mm sockets with ratchet or wrenches, spring compressor tool

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Front shock absorber

Hot Tip:

Spray fasteners with penetration oil and let soak for as long as possible

Performance Gain:

Improves handling over bumps by keeping wheel in contact with road

Complementary Modification:

Change upper control arm if upper ball joint is worn.

As you drive your car the suspension system goes over road irregularities such as potholes and bumps from pavement repair patches. The springs on your car support the weight of it and also absorb the shock of hitting bumps but the coil spring wants to expand back to its normal size immediately after absorbing the shock. This causes the wheel to slam back into the ground. This bouncing around does not help keep the wheel in contact with the road or help with driver control. The job of the shock absorber is to slow down the spring expansion as it recoils. This is known as rebound dampening. The shock absorber does help with compression dampening as well but the main job is rebound dampening. When your shock absorber fails to provide either compression or rebound dampening and you can feel the car continue to bounce up and down after you hit a bump, you need new shocks. This is not a safe way to driver because over a series of bumps the tire will not be in contact with the road surface. The whole idea of owning a Mercedes Benz is its performance, reliability and handling. Mercedes Benz uses what is called a coil-over shock absorber design. This means the spring and the shock absorber are integrated into one part, so if you want to replace the shock you will need to remove the springs. In this tech article we will go over all the steps to replace your shock absorbers.

The shocks' fasteners are going to be tight and there may not be a lot of room to swing the wrench. You are going to have to be patient and use some force to remove fasteners and components to rebuild your front end. Corrosion may hold a component in even after you have loosened a fastener.

Lift and support the front axle of the vehicle. You have to remove the tires to perform this job and it does make access much easier since you may not have access to an automotive lift. See our tech article on jacking and supporting your vehicle safely and removing the front tires.

The procedure to replace the front shock absorbers ends are the same for both the left and right sides. These pictures are of the left side of the vehicle. It is recommended you replace both sides at the same time to keep your handling neutral.

Remember your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

This picture illustrates the right side wheel well looking at the lower control arm from the rear.
Figure 1

This picture illustrates the right side wheel well looking at the lower control arm from the rear. Remove the 21mm fastener. You will have to counter hold the 21mm fastener on the other side of the control arm with a socket or wrench. Pull both fasteners out completely. The lower control arm may drop a small amount, this is normal. You can use a jack on the lower control arm to lift it up when installing the new shock absorber. You do not need to remove the brake caliper and rotor to do this step but we have done so for photographic clarity.

ThisPicture illustrates the top of the left side wheel well.
Figure 2

This picture illustrates the top of the left side wheel well. Remove the 19mm fastener that attaches the upper ball joint to the spindle.

Using a ball joint removal tool, separate the ball joint from the upper spindle.
Figure 3

Using a ball joint removal tool, separate the ball joint from the upper spindle. You can also use a separating fork if you do not have a ball joint removal tool.

To move the upper control arm we must loosen the two 16mm fasteners (green arrows) that mount in the body.
Figure 4

To move the upper control arm we must loosen the two 16mm fasteners (green arrows) that mount in the body. The one on the left is hidden behind the spring. You only have to loosen the fasteners enough to move the upper control arm up out of the way.

Remove the three 13mm fasteners (green arrows) that mount the strut to the body.
Figure 5

Remove the three 13mm fasteners (green arrows) that mount the strut to the body.

Lift up on the upper control arm towards the ceiling of the wheel well while pulling the shock absorber down underneath it.
Figure 6

Lift up on the upper control arm towards the ceiling of the wheel well while pulling the shock absorber down underneath it.

Pull the shock absorber out from underneath the wheel well and lift it off of the lower control arm.
Figure 7

Pull the shock absorber out from underneath the wheel well and lift it off of the lower control arm. This is a 4MATIC which means it is four wheel drive. You will have to lift the lower mount of the shock absorber around the axle shaft as well. Non-4MATIC is similar.

With the shock absorber out of the car use commercially available spring compressors to compress both sides of the spring evenly.
Figure 8

With the shock absorber out of the car use commercially available spring compressors to compress both sides of the spring evenly. Follow the instructions of the tool manufacturer that you are using.

Remove the strut mount protective cap from the top of the strut.
Figure 9

Remove the strut mount protective cap from the top of the strut.

Remove the 17mm fastener (green arrow) that holds the spring/shock absorber assembly together.
Figure 10

Remove the 17mm fastener (green arrow) that holds the spring/shock absorber assembly together. It is recessed in the upper shock absorber mount. Mercedes Benz uses a special socket to get to this fastener and another tool to hold the shock absorber shaft still while you remove the fastener. If you do not have this tool follow the next few steps to remove the upper strut mount.

Using a flat head screwdriver lever down on the inner protective dust boot.
Figure 11

Using a flat head screwdriver lever down on the inner protective dust boot.

Using a flat head screwdriver lever down on the bump stop.
Figure 12

Using a flat head screwdriver lever down on the bump stop.

This picture illustrates the exposed shock absorber shaft.
Figure 13

This picture illustrates the exposed shock absorber shaft.

Using a pair of vise grips and a shop towel wrapped around the shaft (to protect the shaft from the jaws of the vise grips) use a socket to remove the 17mm fastener at the top of the shock absorber mount.
Figure 14

Using a pair of vise grips and a shop towel wrapped around the shaft (to protect the shaft from the jaws of the vise grips) use a socket to remove the 17mm fastener at the top of the shock absorber mount.

Lift the upper shock absorber mount off of the shock absorber.
Figure 15

Lift the upper shock absorber mount off of the shock absorber. HereÂ's a helpful hint for installation of the new shock absorbers: Look at the end of the spring (green arrow) and make sure it fits into the groove for it (yellow arrow) on the bottom of the upper shock absorber mount during installation.

Lift the coil spring, inner protective dust boot and the bump stop from the shock absorber.
Figure 16

Lift the coil spring, inner protective dust boot and the bump stop from the shock absorber. Installation is the reverse of the removal steps. Fit the coil spring, inner protective dust boot and the bump stop on the new shock absorber. Fit the upper shock absorber mount to the top and tighten down the fastener. Remove the spring compressors. Position the bottom of the shock absorber on the front axle shaft and lower control arm but do not install any fasteners yet. Lift the lower control arm up and fit the upper portion of the shock under it and position it in the shock tower on the body. Tighten the three fasteners that hold the shock absorber to the body of the car. Lower the upper control arm to the upper mount on the spindle, tighten its fastener and tighten the two fasteners the upper control arms pivot on. Using a jack line up the lower control arm with the bottom shock absorber mount, install and tighten the fastener. Install the wheel and lower the car. ThatÂ's it. YouÂ're done. Now you can drive around without bouncing all over the place, and enjoy that great Mercedes-Benz handling.

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Comments and Suggestions:
Ron Comments: what are the torque specs to tighten back the upper control arm to the body? is the upper arm supposed to move freely up and down or be tight at a specific height?
November 14, 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.

Should tighten with the suspension in a similar position when the control arm was removed.
- Nick at Pelican Parts
 
Monty Comments: Does anyone know the torque spec for the center top nut on the strut assembly? Is it torqued to spec before install or after its installed and car is back on the ground? Thanks
2006 MB E320 cdi
August 29, 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
 
Kam84 Comments: Did you know that you don't need to remove upper control arm, as soon as the shock absorber ready to pull out just push the hub down for about 3 inches and pull the shocker out, I've replaced mine this morning both side also another tip for everyone who is interested in changing these shock absorbers, on the W211 driver and passenger side shock absorbers are the same. For example you can get a driver side shock absorber and fit on you passenger side.
March 19, 2016
  Followup from the Pelican Staff: Thanks for the tip. Our author found it easiest to get it done with the arm out.

Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Cpl_Jack Comments: Thanks This was excellent tutorial. BTW - These instructions are also accurate for a 2003 E320 as well - all w211 series.

Also, OEM shocks have an adjustable wire ring which allows you to change how much tension is on the spring. When I first saw my shocks, I thought I had the wrong ones.
December 19, 2014
  Followup from the Pelican Staff: Thanks for the feedback. - Nick at Pelican Parts  

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