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Pelican Technical Article:

Front Shock Absorber Replacement

Greg Baxter - Peach Parts

Time:

4 hours4 hrs

Tab:

$300

Talent:

***

Tools:

torque wrench, 5mm hex wrench, 17mm box wrench, spanner wrench

Applicable Models:

Mercedes-Benz W140 (1992-99)

Parts Required:

shock absorbers

Hot Tip:

Have some Blue Lock Tite handy

Performance Gain:

Better handling and suspension

Complementary Modification:

rear accumulator replacement

This is a how-to guide to replace the front shock absorbers on the W-140 body, S-Class Mercedes in mid-late 90s model cars. This article is of my own making, and from my own research. If you use any of the material within then, like me, you're on your own. You can't hold me or anyone else responsible for whatever, so if you don't feel comfortable doing this sort of mechanical work, then take your car to an authorized mechanic.

A while back when I acquired this wonderful automobile, I noticed the suspension was well, somewhat neglected. It had a ride like there was 100 lbs of air in the tires, rattling everything from my teeth to lose interior parts. Sort of like someone had replaced the shocks with cement.

But wait - when I bought it, it only had 65k miles on it, and just 6 years old! Was it really time for new suspension stuff? Certainly neglected by previous "lessee," but hey, it's still a Merc right? So a little fishing around on this site and viola - suspension problems are not only common but are VERY easy to fix. It's almost a routine maintenance item. The rears are more complicated, plus the MB shop wanted quite a sum to do the rear accumulators (no shocks on the rear) - almost $1,400.00. My costs for the rear accumulators was about $300, and maybe the same amount for the fronts.

A few months back I got it up in the air, and replaced the failed accumulators along with some hydraulic lines. But here's the best part - there is simply no words, adjectives or diction I could place in writing that would describe what that little bit of work did for this car's ride. And my back. It went from race car hard to the comfort and luxury the S class W-140s are known for, yet still gave me a sparkling sense of road feel - a combination only found on Mercedes. It was what they were designed for!

Confidently thinking I had solved all of middle Georgia's auto suspension problems, I did notice that although the rear of the car gave me that impeccable ride, there was just something in the front that I could not put my finger on. Something a little stiff maybe, even made the wheel shimmy at certain speeds. New Michelin MX4 Tires/wheels were balanced once again, but no difference. Until I drove a new 2004 S500 - then I knew.

Back to the task at hand - the front shocks. After 70K miles, the front shocks were apparently shot. Remember, it was a salt car from NY, and after all it is going on 8 years old. In the American car maintenance world, shocks are sometimes a 4 year item. So let's give these front shocks a try. You'll also be pleasantly surprised at how simple the procedure is on this car. Dirty, yes. Somewhat laborious, but amazingly simple. As an amateur I'm sure I went around the elbow to get to the thumb. But this is how I did it, and I certainly hope it will help all you DIY's out there that have been contemplating the same task. Good luck!

Top of the shocks stick up through the frame by the motor.
Figure 1

Top of the shocks stick up through the frame by the motor. Pop off all the plastic covers and there it is.

Holding the center of the shock pin w/a 5mm hex, loosen the bolt holding the top of the shock.
Figure 2

Holding the center of the shock pin w/a 5mm hex, loosen the bolt holding the top of the shock. My top bolts were a little stiff, but nothing like the bottoms. Do the top when there's weight on the tires so the springs and shocks are still compressed, and it all stays in place when you take off this nut.

Ok, next step.
Figure 3

Ok, next step. Jack up the front side you're working on, then make your life easy and take off the tire. As you jack it up and the lower control arms extend, the top of the shock will then pull down and out of the top socket since you just removed the top bolt. When the wheels get off the ground, that'll leave it attached only on the bottom. Here's the bottom of the shock as it attaches to the lower control arm. (Notice my cracked boot back there?) The parts are slightly different for 129s, 170s 202s etc.

I put this 17mm on the nut side, and a box wrench on the bolt side to hold it.
Figure 4

I put this 17mm on the nut side, and a box wrench on the bolt side to hold it. A little stiff, I had to use break-free on one side as I remember. I don't show it in the pic, but I actually used an air hammer for this one and it came right off. Notice brake calipers on right.

Pull out the lower bolt from the step above, and the shocks will come right out through the wheel well.
Figure 5

Pull out the lower bolt from the step above, and the shocks will come right out through the wheel well. Don't know why I took this pic, but here they are side by side, old one vs. new one. Notice the new shocks come w/new hardware, which I certainly used instead of re-using the old stuff.

After you bolt the bottoms back on to the lower control arms, torque them to 55 Nm.
Figure 6

After you bolt the bottoms back on to the lower control arms, torque them to 55 Nm. CLICK HERE for a good Nm-to-ft.lb conversion. I used blue Lock Tite. I kept the wheels straight when I did this, as turned one way you can't get to the rear, and turned the other you can't get to the front part of this bolt. It doesn't show it in the pic, but this nut is surprisingly easy to get to w/a 3" extension.

With the wheel still off and springs still extended, this will leave the shock ready and primed to go up into its new home at the top of the wheel well.
Figure 7

With the wheel still off and springs still extended, this will leave the shock ready and primed to go up into its new home at the top of the wheel well. Notice I put graphite paste on the frame socket, but it's not necessary.

Figure 8

Wheel back on, drop the car down an up it goes!

Do the tightening thing again, WIS shows 30Nm on the torque.
Figure 9

Do the tightening thing again, WIS shows 30Nm on the torque. If you want ft.lbs CLICK HERE. I also used blue on this one.
I got my tools off the motor and back in the box, and gave it a whirl not really expecting too much. Boy - was I pleasantly surprised! This simple task had done for the front of my 98 S500 what the accumulators had done for the rear! Even my wife noticed it with a big smile and a comment like "Wow - that's amazing". And, so far, no more shimmy at 55mph like I've been suffering for the last 7 months.

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Comments and Suggestions:
chaz Comments: The best photos/descriptions I've ever experienced and the essential encouragement to continue my quest pampering a sixteen year old 420 with new and needed accessories. At the same time, I'll be twisting and bending in what I have come to recognize as my driveway gym complete with DIY Yoga contortions that among other benefits routinely keep both the car and this driver's joints from creaking...
A Gold medal + a round of applause for Greg,Wayne and Pelican...
Chaz / North Merrick, L.I. NY

August 16, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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