How to change the front shocks and sway bar links in Mercedes w140 S-Class

Changing out worn shocks might be most effective and cheapest fix that can transform the ride handling of your car for the better. My S600 had very noticeable up and down wobbling when driving over bumps and a quite large body roll making in tight corners. It was becoming a bit boat like there at the end. The S600 is a very heavy car and needs good handling when going fast. A flatter ride in corners also makes for a more comfortable drive overall, so your passengers don’t wake up from their naps.

Changing the shocks will reduce wear on other more expensive suspension components like bushings and tires, while overly worn might damage the suspension. Changing the shocks is in your interest to be an economical DIYer.

The front suspension uses normal a McPherson setup with separated gas shocks detached from the springs and can easily be removed. The rear suspension on the other hand uses the more complicated SLS leveling suspension setup and don’t use shocks at all. Instead it uses hydraulic rams along with pressure spheres. More effort and money is needed when doing maintenance on the rear suspension than the front. The SLS however normally lasts a lot longer if you remember to change the fluid once in a while.

When changing the shocks you should also use the opportunity to inspect/change some other wear items easily accessible in the front suspension. This could be sway bar links or the brake rotors and pads. The sway bar links wear down faster than the other suspension components due to their tiny ball joints and should be replaced whenever cracks appear in the sleeves or any slack starts to be noticeable. Worn sway bar links can make annoying sounds for you and your passengers. We all know expensive cars are known for being the most squeaky cars around, let’s change that!

Preparation

You should expect to use around half day to a day on this job, depending on your skill set, the amount of rusty bolts and your tools at disposal. It’s something you can do easily on a weekend. When doing the job I was even under time pressure since I had to catch a flight the same day. I managed to catch the flight and get the job.

If you want to bundle more front suspension jobs while doing the shocks, I recommend removing the front wheels and inspect the suspension such as the sway bar links, brake pads and rotors as well as the tie rods. Any more advanced jobs than that you will will require a lot more time invested so be sure to plan accordingly. Usually large front end jobs require a re-alignment of the suspension, but is not required here.

Parts needed (as described in the article):

  • 2x front shocks. I recommend premium brands such as Bilstein or Meyle
  • 1x Left front sway bar link
  • 1x Right front sway bar link

Tools needed:

I ended up using quite a tool collection because of rusted bolts on the sway bar links, but this might not be the case for you. I think this collection of tools goes into most home car mechanics tool box, but there might be a couple of them you should consider getting. Always better to be prepared than sitting there stuck without finishing the job.

  • Jack and 2 jack stands
  • Socket set
  • Long breaker bar
  • A set of long spanners
  • High quality hex sockets
  • Torque wrench
  • Hammer
  • Rubber/plastic hammer
  • Pin punch driver
  • Locking pliers
  • Long Hex keys
  • Propane blow torch (super handy when things are stuck)
  • XZN (12-spline) sockets (super handy when Hex nut gets rounded off)
  • Blue thread lock (for brake caliper bolts)
XZN socket set
This is how XZN Sockets looks like. They are always a savior when hex bolts gets rounded off.

Procedure

Start by raising the front of the car and remember to use the E-brake together with wheel stops. Place the front on jack stands. I also like to keep the jack in the up position as redundancy on the side I’m working with. You can lift the w140 with the jack on the rubber jacking pad and place the jack stands more towards the center of the car under the sub frame.

Jacking up a Mercedes w140
Jacking up the w140 with a garage jack and jack stands. Notice the rubber pad location is used with the jack and the jack stands are placed under the sub frame. Always use some padding between the car body with the jack and the jack stands, such as hard rubber or some wood to protect the under body from rust.

The shocks can be removed when the calipers are in place, but to remove the sway bar links, both the calipers and the brake rotors need to be removed to access it. I will first describe how to replace the shocks since it is a much easier job. Then I will describe how to replace the sway bar links.

Shocks

Start by removing the lower bolt. Use a long breaker bar and a large spanner to break the bolt loose. Then move to a ratchet to get the nut off. Use the jack to lift the lower suspension arm a little bit to relieve some tension in the bolt through the bracket hole. Then use a punch to smack out the bolt with a hammer. Be careful if the bolt catches too much, then try to relieve more pressure before continuing. Most shocks do not come with replacements for the lower bolt and nut, so try keeping these in good shape.

Removing lower bolt on damper
Remove the lower bolt on the damper.

When the bolt is loose, open the hood and locate the top nut. The top part of the damper can look different from each other. You have to keep the strut bar still with a hex socket or flat pliers while using a spanner to unbolt it. There exists a special tool to do this with a socket, but is frankly unnecessary except if you’re addicted to tools. This locking nut always comes with a replacement nut and you should throw away the old one. When the locking nut is off you can easily remove the old damper.

Location of top part of damper under the hood
Location of top part of the damper. This old damper uses a hex setup for keeping the damper still while loosening the locking nut.

Before installing the new damper, push it completely down a few times to relieve tension. The installation orientation has no influence if the brand does not specify it. Start by installing it with the top part and the top locking nut. When installing the new damper you must take of not letting the damper shaft rotate while turning the locking nut. Keep it secured while fastening the locking nut. This is to reduce the risk of breaking the internal seal of the damper so it will start leaking. The nut does not need to be extremely tight, but do tighten it until you feel it is secure. It is very important to make a re-tight after the car is on the ground. I will remind you of this again shortly.

Now you will probably notice that the new damper is quite shorter than the old one when you took it out. You therefore have to compress the spring by jacking up the lower suspension arm until you can align up the bolt hole. This might be a bit tricky and use a hammer to punch the bolt through since it is nearly impossible to align them up 100%. Again take care of not ruining the threads on the bolt. The lower bolt and nut should be torqued to 80Nm.

Front shocks w140
Old Vs New shocks. Notice the old one even leaks oil!

Front sway bar links

Now on to the more fun part where you can expect to meet more of a challenge. First you need to turn the wheel you’re working on all the way out to get access on the backside. Start by removing the caliper, it is held by two bolts. You may require some force to break them loose. Prepare some method too hook the calipers up in the spring to relieve tension on the flexible brake hoses. Never let them hang freely. I used long zip ties here and I could just to cut it off when done. But a simple S-shaped hook would have been even easier!

Front suspension and caliper
Turn the wheel out completely before starting.

The caliper might be difficult to get off if the brake rotor has a lip on the edge. Use a pry bar or the back side of a hammer to press in the outer brake pad by using the rotor for leverage. Be careful not to damage the pad material. When the caliper is loose, secure it up onto the spring.

Location sway bar link w140
Location of sway bar link. Notice only one accessible bolt. The other one is behind the disk rotor.
Brake caliper w140 removed and hanging
The brake caliper is remove and secured in a zip tie from the spring to relieve tension in the flexible brake hose and brake caliper sensor.

When the brake caliper is loosened you can start remove the break disk rotor. It is secured by a tiny hex nut, but you might find this lost or broken. Mine was broken off on the right side, but the left one was fine. Loosen the nut with a hex socket. If the brake rotor is sticking to the hub, try hammering gently on it with a plastic hammer. If it does not pop off, it can be quite frozen due to rust and you’ll need heat to loosen it. Ignite up your blow torch and heat the area just around the hub. This should expand the rotor just enough so it will pop off with a light hammer blow. Over heating the hub might make the hub grease melt and run out, so be careful with the heat.

Brake rotor locking nut w140
Brake rotor locking nut with hex. This might have broken off already.

Now it’s the time to locate the outer sway bar link nut. Cross your fingers for no rust. It is located right under the brake rotor. The locking mechanism is not the best engineering, since you’ll need either a special tool or trying to combine a socket with some magic tricks. I used a socket, secured it with locking pliers and then used a hex key sticking through it. After some fiddling I managed to get the nut off. You can usually loosen the bolt the first few turns by using just the socket normally.

The upper nut should be the easier of the two to get off, since the lower one usually gets all the rust and is easier to round off the hex bolt head. Soak it thoroughly with rust penetration fluid and let it work for 15 minutes. Then use a hammer and whack that nut good a couple of times.

Removing front sway bar link nut w140
Removing the lower sway bar link nut. Cross your fingers that the hex will not round out. I only got a 50% success rate.

I got lucky with one side, but the other side I had to drive in an over sized XZN socket with a hammer so it’s surely stuck in there. Then I could get enough torque to loosen the rusted nut. This will obviously destroy the part, but it’s thrown out anyway. Unfortunately I did not get any pictures of this process since I was struggling a bit and running out of time.

Broken sway bar link sleeve
The sleeve was broken on the sway bar link. This does not take long until squeaking starts!

Now you should be able to remove the sway bar link. Go fetch the one that fits depending on the side you are working (hopefully you order the correct ones). Fit the top side first, then you move on to the lower side. It can a be a bit tricky to fit the lower side onto the sway bar again. Get a long bar or a long spanner and wedge it between the spring to get leverage to push down on the sway bar.

Use leverage to fit the sway bar link to the sway bar
Use leverage to fit the sway bar link to the sway bar.

It is not necessary to tighten the sway bar links very hard, just snug with enough force so they sit on. Remember these will probably rust tight faster than you can say cheese and the hex bolts will round off again.

old vs new sway bar links
Old vs New Sway bar links.

Caution: Before assembling the rotors, make sure you brush off any old rust off the hub face and the inside of the rotor. This is to prevent rumbling while braking and that the rotor sits on straight! You can use a steel brush and a rough pad to do this. Also brush off any surface rust on the front side of the rotor where it meets the wheel.

The front caliper bolts need a layer of blue thread locker on them since there are no shims or similar. Use 115Nm torque when tightening the caliper bolts.

It can be a bit tricky to mount the wheel if the little rotor locking nut is missing, so a replacement might come in handy here. Otherwise you have to align the hub with the rotor first and then with the wheel when sticking in the bolts.

Now I hope you will take on this task without paying stupid amounts of hours for mechanics to figure this out at a workshop. Go do it yourself!

Cheers, Robs out!

Ride along in w140 S600 from Japan

This video I just made for testing camera equipment, camera placement and angles, the noise quality etc. Watch with this in mind and laugh at the ridiculous intro/outro and some weird cutting.

I used the GoPro Hero4 and built in mic. Some lessons were definitely learned from this recording session:

  1. The gopro mic is not good enough. Use of external mic and good placement is necessary. Inside car is good for louder cars, but for the S600 the mic has to be placed next to the exhaust.
  2. Shooting inside back of car is difficult when it is very bright outside.
  3. Wind noise needs to be dealt with, external mic needs wind muff.
  4. More angles and faster cutting isĀ needed.
  5. Introduction to car and it quirks and voice over might be necessary for most viewers to enjoy such videos.
  6. Wide angle shots not always necessary. I have a camera for this purpose too.

Review of “Flagship” Mercedes Benz S600 W140

The kind Yakuza from Japan

I have been driving the S600 for some days now, in the city, on the highway and more curvy roads in the country side. It is what you can expect from this kind of car: Comfortable, powerful, luxurious, spacious and surprisingly anonymous. It is all what CEOs, diplomats, kings, (or drug lords) can wish for. This is truly an impressive car of by any standards. What surprised me the most is the way it makes you relaxed and do not eager you to drive fast like in a smaller more sporty car, still even when this can reach 288km/h if you remove the electronic speed limiter which is electronically set at 250km/h. What makes this car special are all the perks, accessories and massive comfort, not the ridiculous huge engine which is just a bonus.

Mercedes Benz s600 W140 rear
Rear end of the huge S600, looks even big from this angle. Still anonymous though, only the S600 badge reveals true nature, should be removed for cloaking.

As you turn on the ignition it makes a muted roar and then idles quiet, you can’t even tell the V12 M120 engine is there. It’s actually the most disappointing thing with the car, the engine noise, because it is non existent most of times. Makes sense for keeping the car quiet, but also removes all the fun with having such a powerful car with 400hp. When first driving it you really get surprised just how long and wide the car is, it takes some time to get used to. Driving it along it is like it can drive it self, braking is done by your big toe and steering by your little finger, although I do not recommend this of course. This S600 specimen is from 1996 and is 20 years this very year, but it feels like any modern German luxury car, in fact it feels years ahead of 15 year old newer Range Rovers. With only 58.000km on the odometer it is basically unused and from its Japanese background it makes it more interesting. Still even if it was ordered new in Japan it has the steering wheel on the left side for making it more special when used in Japan. Some buttons and menus in the navigation/radio screen are in Japanese though.

Interior Console Mercedes Benz W140 S600
Interior Console with the V12 badge clearly marked on the gear lever. Why so many buttons though?!

What put me off the most was the acceleration when pushing the throttle just to get up to normal speed. Not a slow one in the traffic!! With that in mind you can drive this like any other car just easing off the pedal more and especially if you have a cake in the back seat unsecured. Driving in the city the car is very comfortable and fast out of intersections, the only problem is narrow roads and parallel parking, but there are parking sensors to help out.

Everything with this car is electric, all the seats including the back seats, electric mirrors, electric windows, electric headrests front and back, electric curtains for the back window, electric servos for closing the doors (yeah you never have to slam the doors, just push the door to the end and they will close the last inch automatically), electric adjustable steering wheel, electric sunroof, electric etc…. and the list goes on.

The S600 has every accessory as standard equipment which is cool and why it was so damned expensive when it came out. The W140 is the biggest and most expensive S-Class model ever made and it didn’t sell well after the legendary W126. It was over-engineered, too pricey compared to the competitors, somewhat dull design and maybe just a little too big even for these kind of cars. After the W140 Mercedes went on a more safe approach with the next model with more success.

So how is the M120 engine? Well it is the most quiet beast of all time. Not sounding like a V12 as you might expect, only a slight orchestral V12 rumble when provoked. Oh God it is willing to drag you along, and the fun does not even stop, it just pulls more and more, I felt the most violent acceleration was when you pass 140km/h. This is truly an engine for high Autobahn speeds, which has very comfortable low RPM when cruising in the mid 100s. It is very easy to loose the license in this car since speed is this car can only be percieved when looking at the speedometer. Speed is unnoticeable, you really have to look twice at the speedometer and double check every time.

Mercedes Benz S600 W140 Engine
The beast of an engine, the M120 with only 48 valves!

Even though this might seem like a sports car, it is not. It’s huge and heavy, even with adaptive damping system and stability things like electronic ESPs of all sorts it feels big. My mind keeps me from going crazy fast since I know this car is big, I don’t even want to go fast, just cruise along at a comfortable pace, arriving in style and not exhausted from overtaking a million times. Even though overtaking cars in this thing is so easy it’s not even fun in the end. Saying this, the handling of the car is amazing and it can be used as a sports car down curvy roads, but it just feels wrong. Keep an eye on that fuel consumption though, it is not insignificant and the 100L tank is for sure needed.

Could I live with this car? Sure! Could I live with the fuel consumption on a daily basis? No. Could I parallel park this every day in the city? Maybe if I had the patience. Could I take all my family and my houseĀ for an epic vacation/road trip with this car? Definitely!

I took some family members on a ride with this thing, they were quite impressed. Especially the back seat with the champagne fridge and so many electric play buttons and all sorts of fun stuff are amusing. Not often a car is more fun in the back seat, that really sums it up for the S600, even though it is so cool and drives like a charm, the backseat is in face a better place to hang out. Being in this car is like sitting in a cloud drinking champagne with your legs stretched fully with the AC blowing chilly on a hot summers day while you raise the rear blinds by the flick of a button to conceal your luxury from the dreadful world outside.

I would recommend this car for comfort seekers and for presidents that don’t mind sitting in the back seat. Driving can be done by more professionals that knows how to drive economically so they don’t use up all the petrol in one night. And that means driving efficiently, comfortable for the passengers and utterly boring.

Mercedes Benz S600 W1400 Front

Cheers, Robs out