Lower Ball Joint Replacement
Newbie
Joined: Dec 2022
Posts: 6
Likes: 3
GL550
Lower Ball Joint
There are two nuts holding the ball joint. The top one is a 24mm nut and the bottom one is a 46mm nut. For the top, you will need a torx bit (I believe T30, but I will double check) to insert into the top of the shaft to stop it from spinning. Because the spindle is in the way, this is only accessible if the control arm has been dropped and you can maneuver it to angle it to the side of the spindle in order to get the torx bit into the top of the shaft. For the bottom nut, I broke it loose using a 46mm socket and then used a vice grips on the rubber boot to stop it from spinning (only because I knew i was replacing the ball joint). However, the proper way is to use a 46mm wrench and hold the bottom of the ball joint with a 16mm hex bit.
Hope this helps anyone looking to do this. I will start a new thread with a write up for the whole process of replacing the control arms, although it has been a pretty straight forward process.
MBWorld Fanatic!
Joined: Feb 2017
Posts: 2,336
Likes: 1,225
From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
Looking at a pic, it looks like the ball joint is pressed in to the steering knuckle. If you can get a pic, we can recommend the tools. Generally the Mercedes are a tight fit for tools and you will need the Mercedes press kit, found on eBay for under a hundred bucks. You will also need a separator, and not a hammer…
Newbie
Joined: Dec 2022
Posts: 6
Likes: 3
GL550
The ball joint is not pressed into the knuckle. It is just wedged in between the lower control arm on the top and the knuckle on the bottom. You do not need a special press kit or a separator for the ball joint (you will need a special kit if you are changing the bushings in the control arm as opposed to buying a new unit). There are threaded shafts on both top/bottom of the ball joint. But yes, the fit for the top bolt is so tight so that you cannot get the box end of a wrench on there and definitely cannot get the torx bit into the top of the shaft to keep it from spinning. I tried pushing the knuckle down in order to get the ball joint out over the top, but it does not move enough to get the ball joint out. So you either need to undo the knuckle or the lower control arm in order to get the ball joint out.
FYI - I ordered replacement ball joints from Eeuroparts and they sent me the Bison brand (which is also branded Moog on the label) ball joint instead of the Lemfoerder version and the bottom threads are not the same as the Mercedes ball joint and it did not come with its own nut, so it is worthless. I would stay away from the Bison ball joints. I will update on the Lemfoerder... which I believe is the OEM. The Bison control arm seems to be of good quality.
FYI - I ordered replacement ball joints from Eeuroparts and they sent me the Bison brand (which is also branded Moog on the label) ball joint instead of the Lemfoerder version and the bottom threads are not the same as the Mercedes ball joint and it did not come with its own nut, so it is worthless. I would stay away from the Bison ball joints. I will update on the Lemfoerder... which I believe is the OEM. The Bison control arm seems to be of good quality.
