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Pelican Technical Article:

Replacing Front Shock Absorbers

Time:

2 hours2 hrs

Tab:

$78 to $250

Talent:

**

Tools:

13mm socket, 17mm wrench, 17mm wrench, large Flathead screwdriver, vise grip pliers, small pry bar, floor jack, jack stands, wheel chocks, safety glasses, lug wrench, torque wrench

Applicable Models:

Mercedes-Benz R107 (1972-80)

Parts Required:

Front shock absorbers Pelican Parts # 107-320-00-30-M12 (Bilstein) or 107-320-00-30-MBZ (OEM)

Hot Tip:

Use copious amounts of penetrating oil

Performance Gain:

Better handing and smoother ride

Complementary Modification:

Upgrade to performance shocks, replace sway bar bushings

One of the most popular projects to perform is the replacement of the front shocks. I usually recommend that you replace both the front and the rear at the same time, as they take the same abuse over their lifetime. As a rule, the shocks should always be replaced in axle pairs either front or rear (left and right together). In this article, we will focus on the replacement of the front shocks.

The shock absorbers should be replaced every five to seven years - 50,000 miles or so, or when they start to feel weak or worn out. These are gas over hydraulic shocks. The "antique" push down on a corner of the car and watch for bounce/rebound will NOT work with these shocks. The gas charge is critical to suspension handling/ride quality, and when it fails the hydraulic component will still pass a bounce/rebound test. Many owners are stunned by the drastic "it's a new car" change in suspension handling/ride quality because the old shocks were driven years beyond failure. Different driving patterns may also affect the life of shock absorbers. Cars that are raced or driven hard on windy roads may need to have their shocks replaced more often than typical road cars. It is important to remember if you install performance springs into your car that raise or lower it from its stock level, you will need to have the car realigned and install shocks that are designed to work with the shorter springs. Changing the height of the suspension changes the values of the suspension settings.

The total weight of a car is supported by the springs at each suspension corner of the vehicle. As you drive your car the wheels hit bumps and the spring absorbs the shock of the bump. The coil spring does not want to stay compressed. It wants to expand back to its normal height as fast as it can. This would of course slam the wheel back into the ground creating another impact with the road. Since you are still driving, you will also hit additional bumps so the process repeats itself. While you are driving this would feel like the front end is bouncing up and down. At high speeds this can lead to a loss of traction and poor road feel. The shock absorber does help a little while the spring is being compressed but the main purpose is to slowly bring the spring back to its normal height so it does not slam back into the road surface. This is known as rebound dampening. When a shock "blows" internally it does not have any rebound dampening so the front end bounces up and down. In this tech article we will show you all the steps to replace your front shock absorbers.

These 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. Use liberal amounts of penetrating oil to free the bolts.

Changing the shocks is relatively easy, requiring the use of various sockets and a floor jack. The first thing to do is jack the car up and support it safely on jack stands. NEVER rely on a floor jack to hold the car up. The first step is to place a floor jack under the front brake disc. This prevents the control arm from flying downward once the upper control arm link and shock are disconnected. Once the car is jacked up, remove both front wheels and open the hood. Please refer to our article on jacking up your car for more info. Once secured, remove the front wheel. Once the wheel is removed, you'll see all the components that make up the front suspension.

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

Remember that 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. At the top of the car, inside the engine bay, you'll see the upper shock mounting nuts. The upper connection for the shock absorber uses a rubber grommet, large washer and two lock nuts to hold it in place on the body. The windshield wiper fluid reservoir will have to be removed to get to the passenger side front shock absorber.

Before you do any work on your car it is important that you wear safety glasses and work gloves. If you have to jack up your car, make sure to use jack stands and chock your wheels as well as applying the parking brake. Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. Never work on your vehicle if you feel the task is beyond your ability. Always disconnect the battery before working on your car.

With the windshield washer reservoir moved out of the way, you have access to the two lock nuts holding the top of the shock inside the car.
Figure 1

With the windshield washer reservoir moved out of the way, you have access to the two lock nuts holding the top of the shock inside the car.

Hold the bottom 17mm nut with an open end wrench while you loosen and remove the top nut with a 17mm socket as shown here.
Figure 2

Hold the bottom 17mm nut with an open end wrench while you loosen and remove the top nut with a 17mm socket as shown here.

Use a set of vise grips to hold the flat part at the top of the shock rod and remove the 17mm nut at the bottom.
Figure 3

Use a set of vise grips to hold the flat part at the top of the shock rod and remove the 17mm nut at the bottom.

Remove the upper washer securing the rubber grommet to the body.
Figure 4

Remove the upper washer securing the rubber grommet to the body.

Using a large flathead screwdriver, pry the rubber grommet up and off the shock rod (green arrow).
Figure 5

Using a large flathead screwdriver, pry the rubber grommet up and off the shock rod (green arrow). This might take a little effort, but it should come right off.

The rubber grommet may have to be replaced.
Figure 6

The rubber grommet may have to be replaced. Check for cracks.

There will be two 13mm nuts that hold the shock absorber to the lower control arm.
Figure 7

There will be two 13mm nuts that hold the shock absorber to the lower control arm.

Using a 8mm socket wrench, loosen and remove the bolts.
Figure 8

Using a 8mm socket wrench, loosen and remove the bolts.

Using a large flathead screwdriver, shift the bottom of the shock up in order to help create room to remove the shock past the upper control arm.
Figure 9

Using a large flathead screwdriver, shift the bottom of the shock up in order to help create room to remove the shock past the upper control arm.

Use a small pry bar to push down on the shock.
Figure 10

Use a small pry bar to push down on the shock. Doing so will help compress the shock for removal.

Grasp the shock absorber and compress it.
Figure 11

Grasp the shock absorber and compress it. It will take a little force but it will compress. 

After the shock absorber is compressed it can be removed from your car.
Figure 12

After the shock absorber is compressed it can be removed from your car. Installation is the reverse of removal.

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