The title of the this thread is related to all of the threads that were involved in my most recent repair adventure with my 2002 S500, and the related answers, tricks, and tips.
PLEASE NOTE THAT THIS POST IS ONLY MEANT AS A PARTIAL EXPLANATION OF THE PROCEDURES FOR THESE REPAIRS AND THE READER ASSUMES ALL RESPONSIBILITY FOR SAFETY AND DAMAGES AND IS URGED TO SEEK PROFESSIONAL ADVICE BEFORE DOING THESE REPAIRS.
It all began with a routine oil change and undercarriage inspection when I noticed that the inboard attachment of the driver side lower control arm was worn out, and the passenger side was also starting to fail. Peterstar was able to provide a great description of the repair so I decided to proceed. I also decided that since the control arms were coming off that I should go ahead and change the ball joints. The driver inner tie rod had some play as did the outers; and if I was this far I might as well change out the knuckle arms (lateral control arms).
While I repaired both sides of the car, I only repaired one side at a time so I always have the other side as a reference.
Removing the knuckle control arm as a first step really frees up the area for further work. Please note that it is essential to use a 5mm hex key to hold the center stud from turning when removing the 21mm nut at the wheel hub. I used a long handled key with a Blackhawk brand 21mm ratcheting closed end wrench. The ratcheting wrench allows the user the ability to really get to areas where a regular ratchet and socket will not fit.
The nut removed quite easily and then I set up a pitman type puller to push out the stud. I strongly recommend the Mercedes puller in that it is designed perfectly for this application and really grips very well to the hub. The puller was used with an impact wrench set at 400 pounds. With the release of the lateral arm at the hub I then removed the inner end using a 21mm closed end wrench on the bolt and the 21mm closed end ratchet wrench on the nut. After removing the bold the arm pulled out with a strong couple of tugs.
Using the Mercedes puller I then disengaged the outer tie rod from the hub. (I did NOT loosen the retaining nut on tie rod itself and will explain latter.) Reaching up to the inner tie rod end I removed the inner boot clamp at the rack and pinion, and pulled back the boot. The rack is ground on two sides to accept a 27mm open end wrench in order to stabilize the rack when removing the inner tie rod. The inner tie rod has small flat spots which will perfectly fit a 41mm wrench. The flat spots are rather small and subject to easy rounding and I would recommend not using an adjustable wrench on either the rack or the tie rod end, but invest in the correct sized wrench. In this case I used a 41mm crows foot.
I removed the inner tie rod as one assembly and brought it to the workbench where I clamped a block of wood to the work bench at either end of the tie rod assembly so that the distance between the wood blocks was the EXACT distance of the length of the tie rod assembly. Then I took the new inner and outer tie rods with the boot and stop nut, and assembled them between the blocks of wood so they fit exactly between the blocks of wood. You can try counting the turns of the outer tie rod, but the length of the new pieces might be different. In this case the outer was identical, but the inner was approximately 5mm shorter.
Leaving the tie rod assembly on the workbench it was time to head to the lower control assembly. To take the pressure off of the airmatic strut I cracked open the line at the head of the strut and released the air. Then comes the most difficult part of the entire procedure, which is removing the stabilizer bar link. There is a great deal of tension on this link, but by placing a jack under the lower control arm I was able to raise and lower the control arm until the pressure was lessened on the link. Once I was satisfied that the tension was as low as possible, I drove the bracket off of the control arm by tapping a block of wood against the bracket with a rubber mallet. I did not want to snap the bracket by striking it with a sharp metal object.
From this point I simply backed off the airmatic set screws, removed the bolt at the inboard bracket, and allowed the control arm to pivot downward while still attached to the ball joint. The nut was removed that held the control arm to the ball joint, and the lower control arm was separated from the ball joint by use of the puller.
In order to remove the ball joint, I used the W220 ball joint tool and I could not have been more pleased. The instructions were very straightforward and really made this job very workable.
Reassembly was in reverse order, but I must mention some very critical steps:
- The stabilizer bracket hole is hexagonal and is designed to fit the hexagonal base of the bolt on the new lower control arm. When you get the bracket over the bolt, then get the nut to catch and work the bracket inward while at the same time moving the hex wrench on the bolt. In this was you will catch the whole in the bracket properly and allow the stabilizer to seat.
- The bolts for the control arms should only be tightened when the weight of the vehicle is resting fully on the suspension. You might need to let the vehicle rest on jack stands under the lower control arms or have the vehicle on ramps.
- Also, the new inner tie rod needed a 36mm crows foot.
Having started and completed the driver side I went to the passenger side and ran in to a very nasty problem: the rear facing airmatic set screw was jammed. I tried heat, leverage, penetrating oil, and every combination I could think of and it would not budge. I even reassemble everything and went to my local tire shop where their impact wrench could hit at over 1000 pounds……….nothing!
So I decided to once again remove the knuckle arm and the tie rod, and then drop out the lower control arm while still attached to the airmatic. My main concern for the airmatic was making sure that air input was sealed from dirt, but luckily I had saved the brass fitting that came from the factory. So after removing and covering the airline with a plastic bag, I then installed the brass plug and released the three nuts at the top of the strut. It took some twist and turns but the airmatic and the control arm were removed and placed on my work bench.
I had determined that the set screw was a 10mm with a 1.0 pitch, and I was able to get at set from the dealer. I turned the strut so that the stuck screw was facing upward and placed it in a jig to hold steady and level in a drill press. The 5mm hex head fitting in the screw forms a perfect guide to allow a pilot hole to be drilled straight through the screw. (Remember: I was replacing the lower control arm, so I didn’t care if I damaged the control arm fitting.) Using plenty of drill oil and steady pressure from the drill press, I was able to drill out the screw all the way through to the lower control arm. Once the strut was free of the control arm I then used a 10x1.0 tap and recut/cleaned the threads. The new screw fits perfectly and reassembly went well.
At the end of this whole process the vehicle drives dead straight down the road without a single noise or vibration, which I couldn’t say before! This will be followed by new tires and an alignment.
Some notes on tools:
41mm crows foot
Mercedes Puller 124 589 03 33 00
Amazon.com or eBay
Look for the W220 ball joint tool
Some notes on parts
Lateral control arm aka knuckle arm: $79.00
Lower control arm: $85.00
Inner tie rod: Febi $21.09
Outer tie rod: Febi $ 33.06
Tie rod boot: 10.26
Ball joint: 49.75
Airmatic strut set screws, A 000 990 44 77: $4.60
Total cost of parts: $560.92