Need tip on changing upper control arm on W210 - PeachParts Mercedes-Benz Forum

Pweber · #1 03-31-2007, 11:14 PM

Needing to replace the pass. side upper control arm. I can see the head of the pivot bolt right behind the air box. Without tearing a bunch of things apart I thought I would ask for some expert advise as to how to get to the nut on the other side. Also, I was at a good break point tonight. (I have the ball joint and lower control arm loose at this point including the spindle ass. off so I have a free hanging upper control arm)

kwmccauley · #2 04-01-2007, 04:59 PM

My car is a 1999 diesel with Turbocharger. It should be similar to yours but not exactly the same.
Well, that control arm you mention was probably the most challenging part of the job, except perhaps for the upper control arm on the driver's side.
The bolt head for the upper control arm that goes thorugh the fender well is, as it sounds like you know at this point, 15mm. The nut on the other end is 16mm. Once you get access (see below), use an offset box wrench to hold that. Loosen using the 15mm bolt head.
Here is what I had to do to get access. I have some digital photos I could send to you if this explanation does not sound sufficiently detailed. On the passenger side, remove the air cleaner cover, filter element and air cleaner box (housing). The air box is a press fit into a large rubber grommet in the frame. After you remove the top and filter element, disconnect the hose at the front and the box should swing up and out of the way so you can see what you are doing to get to the front 15mm bolt head.
This next step seems really overwhelming at first look but just go slow and it is not too bad. It goes back really easily. The photo I took in advance definitely helped me with the reassembly.
To get to the rear 16mm nut, carefully remove the cover to the electronic control module box. Disconnect the connectors then remove the control modules (I have a good picture I can send you on this too). They slide out like index cards in a file box. Once the modules are out, loosen the four screws holding the control module housing upper section to the lower base. Swing the box upper half up and toward the front of the car. I then used some simple wooden shims to go between the lower housing and the rear of the front fender well. SLIGHTLY deflect the lower box front lip toward the rear of the car. Now you will be able to see the 16mm nut. Hold that and undo the bolt head from the front of the fender well. When you put in the new control arm, do not tighten this bolt and nut to the specificed torque value until the car is resting on its wheels. Obviously, it is not possible to start the car with all of the electronic modules hanging out. What I did was to lower the wheels on to a set of ramps once I had the suspension components reconnected.

Do you already have the driver's side complete? If not, I'll send some info on that as well.
Please send me your e-mail address if you want me to send some photos.
Hope all goes well!
Ken

Pweber · #3 04-01-2007, 09:27 PM

Thanks Ken. I am just doing the pass. side as it was in a minor wreck that damaged the right front suspension. Upper control arm looks ok but may be tweeked a bit so I am replacing it. I will try this over the next few days. Thanks again.

yiannit93 · #4 08-17-2011, 01:14 PM

Kwmccualey i need help replacing the left front upper control arm. i saw above you have knowledge on how to do this and i need to finish asap. if you can send me any tips and information it would be greatly appreciated.

kwmccauley · #5 08-17-2011, 06:26 PM

This is a quick response to acknowledge your message and provide some basic information. The next time I will be able to access my records is Saturday so for now I will provide some comments from memory of the replacement which was now more than 100,000 miles ago on my 1999 E300 Turbodiesel. The replacement was done as part of a full front suspension rebuild at about 172,000 miles. The car now has 287,000 miles. Since the full rebuild was done, I have again replaced the lower ball joints and stabilizer bar end links.

You mentioned the left upper control arm which to me means the left side as one sits in the car looking forward. This is also the side with the upper control arm that is easier to replace. You will need the upper control arm which comes with a new upper ball joint pre-installed. It is also recommended in the MB WIS that you get a new bolt and self-locking nut.

The head of the bolt and the nut on your existing upper control arm are accessed through the engine compartment. The approximate location will be obvious when you see on the new control arm where the long bolt fits through the arm. Once I had the car safely supported by sturdy jackstands, I removed the front wheel and removed the very heavy spring that goes between the lower control arm and the spring perch. This was done with a
W210 model-specific rented spring compressor tool (available for rental on the tool rental forum of this Peach Parts site). I do not remember if the spring removal is necessary if you are only changing the upper control arm but I did remove it because of the complete front suspension rebuild work I was doing. Removal of the spring is potentially VERY hazardous if not done properly or if attempted with an improper or defective tool.

You will also need a ball joint separation tool. These are also available in the Peach Parts tool rental program or possibly at your local auto parts store in their rental program.

After you install the new control arm, the long through bolt and nut must be torqued to a specific value. I believe the torque must be set when the weight of the car is on the wheels with the suspension in its natural at-rest state. The nut that attaches to the upper ball joint stud also has a specific torque value. As I recall, the torque values may have been posted in an earlier thread about this type of repair job. When you are done with the replacement and all is back together the car will need a front wheel alignment since the work you just completed changed the alignment settings on the left side.

All of the above comments and information are intended to be of assistance to you. I am not a certified mechanic and assume no liability for anything related to repair of your vehicle. This is all in the spirit of sharing my own personal experience with this repair that may or may not be similar to yours.

Others on this forum may have more recent experience doing this repair and have access to the correct part numbers, torque values and WIS files.
Hope this is helpful to you.
Ken

kwmccauley · #6 08-17-2011, 06:38 PM

Yiannit93,

Here is a link to an old post from March 31, 2007 that may be useful:

http://www.peachparts.com/shopforum/showthread.php?t=183963

Also attached is a PDF file with torque values and part numbers that were current at the time the work was done early in 2007.
Ken

yiannit93 · #7 09-26-2011, 05:27 PM

thank you very much for the info sorry for the late reply. i did get it done finally