I replaced the front lower control arm on my w212. I used a ball joint separator on the old one and popped it out. I then unbolted the frame bushing and slid it out.

I put the new control arm in bushing first. I tightened the bolt while holding the control arm straight at a 90° angle. The new ball joint no longer lines up with the hole it goes in on the wheel hub. There isn't enough movement in the wheel hub to make the ball joint line up again.

After trying many different things I had to fasten a ratchet strap to the wheel hub using a lug nut, then around a fence post and pulled the whole wheel hub inwards. After putting a lot of tension on it, there was a loud bang and the ball joint suddenly lined up and I was able to drop it right into place.

This 1 hour job took me 8 hours because i couldnt figure out how to make it line up again. I now have to do the other side and am afraid this will happen again.

Does anyone know why it would pop out of place? I didn't jack up the wheel hub or do anything to it. Is there a proper way to get it back in position if it does go out of line?

Why would it bang and then suddenly be in alignment again? Does anyone know what went wrong?

 

It's weird your weel hub would not go back... is this a 4Matic or RWD?

 

it is the 4matic awd.

 

okay then you are fighting the shaft that got pulled out. It needs to be guided back and locked in.

 

Is that supposed to happen? In the videos I watched this didn't happen at all.

If i put a jack under the wheel hub before i disconnected the control arm would it hold it in place?

 

The shaft is under no real tension to get out because the link you are replacing holds everything in place until removed ...

Keep the hub from hoing side ways so shaft is not pulled.

Beware with a jack under the hub you're dealing with strong spring compression. Instead use a helper or one hand or a knee to hold your loose hub in place.

 

So is it left and right movement that unseats the axle or does it just fall out of place when the control arm is removed?

I have to replace the CV axle on that side anyway so maybe I can just remove it before i mess with the control arm?

 

yes that would be 3 birds with one stone

 

OP thank you for this thread. I have been contemplating replacing my lower control arms and hadn't considered the front axle coming loose.

 

Its worth it to replace them. I only did mine because of a clunk sound. After replacing it the ride quality is so much better and theres minimal road vibration. I didnt realize how much this part mattered for ride quality.

Dont turn the wheel after disconnecting the ball joint. Thats what made my CV axle come out.

 

I hope you tightened the suspension arm at ride height.....otherwise the bushing life will be short when and if it was tightened during full suspension droop.

On a happy note :
Glad the ride improved, it should.

 

Hi all @S-Prihadi @Black-w212 @CaliBenzDriver ,

It looks like I might have to do this job soon myself (I will update after my trip to the independent service garage next week). Glad you got your new control arms on! Besides this, did you encounter any other huge pains or troubles while doing the job? How did you know it was time to change the front lower control arm in particular?

- Andrew

 

At 130k Miles suspension work is awaiting for repairs. All the rubber bushings are soft & loose...

This is why vehicle tracks poorly with steering feeling imprecise + floating.

1. 2+2 swaybar links
2. 2+2 control arms
3. 1+1 ball joints
4. camber balts
5. (tie rods: inner+outer)
6. wheel bearings freeplay !?!
7. 2x (struts) + top bearings

 

As noted above make sure the nut and bolt at the inner bushing side is tightened down in ready to drive position- car resting on its wheels.

With the strut and the torque strut still installed I cant imagine the cv axle coming out.

When I do front suspension work i'll use a spare scissor jack placed under the rotor either to hold it at a certain height or even raise it while gently pushing in or pulling out on the wheel carrier to align things.

 

I watched a video about someone explaining why the lower control arms were a bad design on this car and they were failing after 10k miles. My car was making a terrible clunking and grinding when turning sharp at low speeds. I couldn't see anything wrong with my control arm bushings but replaced 1 anyway. The clunk sound was gone on the side I replaced but could still be heard from the opposite side. I then replaced the other one and the sound was completely gone. The only damage I see on the bushing is dry rot on the rubber part.

I did mine with a floor jack in my driveway. It is just a ball joint and 1 big 21mm bolt. You need a long ratchet, 21mm wrench, and a ball joint separator from AutoZone. If you tighten the control arm at a 90 degree angle you don't need to torque at ride height. I put my car on ramps and torqued it at ride height anyway, but it is not required if you do it right.

 

I watched a TRQ repair video where the lower control arm was replaced on a W204 and the technician removed the center bolt on the front wheel and separated the axle from the hub. Is this necessary or do you still recommend holding it in place when removing the control arm?

I’ll be replacing the front upper and lower control arms as well as the sway bar end links on both sides. I’ve never really done suspension work like this, so we’ll see what happens. Do you recommend an alignment after?

 

It doesn't need an alignment unless you do tie rods. The control arms are not adjustable so it goes back the exact same way you took it off.

You do not need to unbolt the axle. Literally just pop the ball joint and take out the frame side bolt and you're good. DO NOT TURN THE WHEEL. This is what caused my axle to pull out. Just pop it out, don't move it, and put the new one in. Took me 15 minutes when I didn't mess with the axle.

 

+1

 

Contemplating replacing my lower control arms tomorrow. Trying to get my confidence up. Will have the car up on jack stands. Is the orientation of the frame bolts such that I will have enough length to put a cheater on the wrench to completely torque them? Also regarding the angle, thinking I will disconnect the ball joint first and mark the orientation of the arm on the frame before I loosed it. Any problems with that plan?

 

The angle is really awkward. I wasnt able to use a breaker bar. Instead i used a 1/2" drive adjustable ratchet from harbor freight. That bolt can be really tight and you have limited room. The good news is thats the hardest part of the job. Oddly enough, the bolt on my broken arm was already loose. The other one was super tight.

You dont need to mark it. It will go in exactly how it came out. Theres no way to mess it up. I highly recommend watching the video on it by "exotic car DIY" on youtube. He actually proves that the alignment is unchanged after the replacement.

 

Thank you for your response. I just wanted his video. Nice tip on the 180 and 90 degree marks. Thank you for that recommendation. To be clear the angle I was referring to was the 90 degree angle that the arm makes going to the strut.

One of the remaining worries I have is the same issue you had and that is I have a 4matic and a little worried about jostling the strut around to get the ball joint lined up. Thinking I can get that lined up first and then insert the bushing end into the frame.

Last issue is that they could not bring my alignment into spec so I bought the adjustable camber bolts. I am thinking I will use the factory bolt to line it up and then put in the adjustable bolts. Alternatively I could just put the factory bolts in and give the adjustment bolts to the alignment guy if it needs them. That actually might be a better plan.
Opinion?

One last comment my car is making a knock noise when I am sitting there and turn the wheel. I am hoping that this is the source but doubt that I am that lucky.

 

As long as you dont move the wheel after popping the ball joint, it will go back in very easily. It's not like you bump it and it's out of place, you have to forcefully move it around to mess it up.

As for the alignment, I would install the adjustable bolt and drive it to the shop with the bad alignment and have them get it in spec. They're going to charge you for assembly if you just give them the bolt and tell them to install it. Make sure you tell them it's an adjustable bolt though, they might ignore it thinking it's just the regular one.

 

Update; Contrary to what my dealership service advisor told me, my lower control arms already has the camber adjustment bolts. My question now is does the lower control arm frame have features as shown below for where the adjustable bolts would engage. Looking at the video a couple of times it looks like it does. Let me know if I am wrong.

If so what this means is that one should not apply the torque to the adjustable bolt head to prevent damaging the frame locks. This would not be the case for the normal bolts as they would not engage the frame locks. As pointed out in the video there is no room for the head of a torque wrench on the nut side of the bolt and the bolt extends quite a bit beyond the end of the nut. It seems to me that you would need a 1/2 drive 21 mm 6 point crows foot to loosen and tighten the adjustable bolt nut. Do professional mechanics keeps these in their tool boxes?

Seems like another option might be a deep socket but you would have to drop the anti roll bar.

@S-Prihadi as the image below is from your post, how did you loosen / tighten your camber bolts?

@Black-w212 it sounds like you put yours up on ramps. Thinking that would give you more room to work that jack stands.

In other news I think I found why my car is all over the place. There is a observable rotational freeplay in the upper control arm. It does look like the bushing is shot again. Thinking I will rebush a new control arm this time. Which is another topic. The reason I rebushed the original control arms vs replacing the control are with one with the bushing already installed is I was concerned about getting a non OE bushing which might be solid vs hydraulic and negative impact the vibration transmission. I should have asked the following question the first go around. Are any of the already bushed control arms OE quality in terms of the bushing be hydraulic? I got Lemforder bushings last time.

 

The frame has the notch already even if you don't have the adjustable bolt.

There really is no socket that fits that nut. Your only option is to use a regular wrench. There isn't enough room back there for any type of ratchet and socket.

The control arms don't really throw off alignment. When they go bad you just get clunking, stiff steering, and more road vibration. If your alignment is super off I would look at tie rods more than anything.

Its possible that the control arm is super messed up if you hit a curb, but my money is on the tie rods. Do you get vibrations at higher speeds?

 

To torque nuts that are in tight spots to fit a socket on they have torque extensions. This is a cheap option if you already have the regular ratchet type torque wrench.