4Matic Front Lower Control Arm Outer Bushing

20414 Views 59 Replies 9 Participants Last post by Kuhyuan, Feb 3, 2022

ezzo

Discussion Starter · Apr 11, 2019

I thought I would make a thread to the fellow 4Matic owners who may have problems with the front lower control arm outer bushings.
I started to have cluncking noises coming from the front suspension whenever I go over little bumps.
After I visually inspected with a pry bar (watch video below),

and after hours of researching and price checking, I decided to go ahead and replace the bushings only (not the control arms themselves).

Please make sure to jack the car up safely on jack stands. I used wramps for the rear wheels as well. I used 6 tons jack stands, but you can also use the 3 tons.
You will need to remove the 18mm bolt and nut of the sway bar (torsion bar, also called stabilizer bar) linkage to be able to remove the 21mm bolt holding the strut to the bushing. I might have been able to do without this by using a jack to lift the linkage up. This is something I regreted afterwards as I unintendedly dissassembled the linkage bolt/nut and eventually did not replace them. Check this post here (https://www.benzworld.org/forums/17753306-post5.html)

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ezzo

Discussion Starter · #2 · Apr 11, 2019 (Edited)

Let me back up here a little bit. Whole control arm replacement is expensive (parts), and very hard (require subframe dissassembly). See the service manual pages for the front lower control arm replacement attached to this post.

The outer bushing is not sold separately at the dealership. The part number is A2113331914.

Other part numbers are:

SWAG 10 92 1540
FEBI BILSTEIN 21540
AYWIPARTS AW1420044
LYNXauto C8432
MAPCO 37875
MEYLE 014 033 0091
LEMFÖRDER 2604401
MOOG ME-SB-2730

I decided to go wtih the "LEMFÖRDER 2604401". They are available on eEuroparts as well as FCPEuro and very cheap ($8 each).

I had an initial attempt at replacing the bushings (please see my post https://www.benzworld.org/forums/17721884-post8.html) and I could not figure out how I could move the strut out of the way to gain access to the bushings!

@amosfella suggested that I could remove the three nuts holding the strut from the top (https://www.benzworld.org/forums/17722232-post9.html).

I had another idea that I thought I would try first, which was to compress the coil over spring so the strut lower end can be lifted up to gain access to the bushings (check the pictures below). Unfortunately, this did not work.

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ezzo

Discussion Starter · #3 · Apr 11, 2019

I ended up removing the three nuts holding the strut from the top. Thanks @amosfella :smile!
And, this turned out to be very easy and did not affect the alignement. In fact, the W211 chassis does not have camber or caster adjustments with OEM suspension parts. So, removing the nuts should not affect the alignment at all!

I could then clearly access the bushing and use the tools to remove it. What's that little groove in the hole there?

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ezzo

Discussion Starter · #4 · Apr 11, 2019

Notice the groove in the OEM bushing's hole? the "LEMFÖRDER 2604401" part did not have one! But I did mark the point where the bushing cut is placed (see picture). I don't think this would even matter but I thought I would insert the new bushing in the same fashion.

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ezzo

Discussion Starter · #5 · Apr 11, 2019

Unfortunately, I did not have the bushing removal tool handy that day. So I improvised using some cups in a ball joint removal tool with some wrench sockets (1-7/8) inch.
Because the bushing socket is tappered, you should only attempt to "push" the bushing from the rear to the front (with respect to the car that is). You will notice that the diameter of the socket if measured from the rear is 50mm, and when measure from the front is 51mm. The diamter of the cup that should push the bushing should not exceed 48mm so it can fit inside the socket when operating the removal tool.

After some muscle crunching and twisting, I finally got the bushing out!

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ezzo

Discussion Starter · #6 · Apr 11, 2019

Now comes the not so fun part! Since I did not have the right bushing removal/insertion tool, I ended up damaging the bushing to some degree. The cups I used had thin walls and were not the right size for the job. Each millimeter can make a difference here.

In addition, it seems I did not get the cup pressing the bushing aligned with the new bushing, which in turn was not aligned with the control arm. In addition, pressing the bushing inside its socket required a lot of torque and any movement while doing so would end up having the bushing inserted "unevenly"! Check the pictures.

I ended up using a mallet to get the bushing straight, which ended up bending the outer aluminum shell of the bushing!
In addition, even when starting with the bushing aligned with my mark, when it was pressed, it rotated counter clockwise and the busing's shell opening ended up above my mark!

The end result turned out to be ok, but not what I wanted. Check the last picture below.

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ezzo

Discussion Starter · #7 · Apr 11, 2019

Important note: Tightening the nuts should be to specs and should be done when the car is on the ground. This ensures that the suspension components (bushings, sway bar, etc.) are in the "normal" orientation and are under the "normal" pressure.

I am attaching here some service manual pages related to this job for the steps and torque specs.

For the expert moderators of this forum, please let me know what you think of this procedure. Any advice, warning, or even a tip I, and others, should be aware of?

ps2cho

· #8 · Apr 11, 2019

How on earth did you find the part# for that bushing? I searched tirelessly for it years ago, then ended up replacing the entire arm. Its not shown on the EPC either.

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Noodles

· #9 · Apr 11, 2019

Fantastic write with pics and part info. This is on my list for the summer and the post will be valuable.

Thank you ezzo!

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ezzo

Discussion Starter · #10 · Apr 13, 2019

ps2cho said:
How on earth did you find the part# for that bushing? I searched tirelessly for it years ago, then ended up replacing the entire arm. Its not shown on the EPC either.

I, too, searched tirelessly, but allow me to walk you through my mental process at the time.

I searched by all sorts of keywords and part numbers until I got lucky; I found this item on amazon:
https://www.amazon.com/gp/product/B00HCP146U/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
that seemed to be related.
At the time of writing this, it still has only one review:
https://www.amazon.com/gp/customer-...ef=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B00HCP146U
and the guy said it was for the W211 4Matic. I purchased this Febest bushing (see the unboxing picture below), but turned out to be a cheap chinese after-market that's even more expensive than the LEMFÖRDER. I did not know LEMFÖRDER's part number at the time!

I started by comparing the febest part to what I saw when I jacked the car up for inspection. The rubber pattern, the alumimnum shell and core, and the sizes seemed to match. When searching for https://febestparts.com/ARM_BUSHING_FRONT_LOWER_ARM/BZAB-038, I found a lot of pictures coming up in Google images with the 4Matic lower control arm and that bushing was very clear to match.

When I received the Febest bushing, I took the measurements (check pictures) and compared to what's on the car. They matched. When I received Febest, I had already found the cross reference part numbers:
SWAG 10 92 1540
FEBI BILSTEIN 21540
AYWIPARTS AW1420044
LYNXauto C8432
MAPCO 37875
MEYLE 014 033 0091
LEMFÖRDER 2604401
MOOG ME-SB-2730

I just had to return Febest and get the LEMFÖRDER. It is available on eEuroparts and FCPEuro. Of course, I had to pay for the shipping back to Febest USA :banghead:, but at least I learned something and got the OEM brand! :whipped:

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ps2cho

· #11 · Apr 13, 2019

Many thanks!
I'm going to check my bushing due to this thread. I have a long standing clunk over bumps that I've replaced almost everything and I'm going loopy over it. This gives me one additional item to verify, thanks.

ps2cho

· #12 · Apr 14, 2019

Thoughts on the condition of mine? They don't seem to flex as much as yours does in the video, but there seems to be a small crack as you can see.

I'm leaning that maybe this is also the clunk I'm getting over bumps? Want to see if you agree since you've had your bushing completely out and probably was able to inspect better.

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ezzo

Discussion Starter · #13 · Apr 14, 2019

This is a very clear picture. I can see the cracks and they are not "small"!. Please check the arrows in the first picture.
The reason mine was flexing is becuase I was applying a lot of force with the pry bar. Don't be shy to apply some force with your pry bar. You car puts more load than what you can with your pry bar. This is the only way you can diagnose the issue.

Having said that, I just would like you to note that the bushing is made out of three layers of aluminum as I illustrate in the second picture. The only thing holding the three layers together is the rubber. I believe that once you have cracks in the rubber, the three layers start to clunk together.

Conclusion, your bushing looks as bad as mine was. This is very likely the cause of the clunking you are getting over bumps. It is up to you if you woud like to change it, since you have already replaced the entire arm.

BTW, how difficult was replacing the entire arm? Do you know the procedure that was done to replace it?

Let me know if I can be of any help.

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ps2cho

· #14 · Apr 14, 2019 (Edited)

Ok great thanks! I’ve ordered two new bushings.

I think the problem originated from the fact I mistakenly torqued the new arm when the car was not on the ground at ride height.

The arm replacement does not require anything special, disconnect the ball joint (lower) and lower strut forks, unbolt, and remove, that’s it.

The engine lifting you are talking about is for the anti roll bar removal. The FSM states it’s required to remove it, however even that you can get around if you grind down an Allen key

I’ve ordered new bushings and will press them in and hopefully that’s going to resolve the issue! It started clunking about 10-15k after I replaced the arm and I’ve replaced the strut, coil, sway bar links, inner arm bushings (they were cracked and twisted already due to my mistake).

I feel like this is the problem finally and am very thankful your thread popped up and made me jog my brain thinking this has GOT to be it!

In addition, my chassisears tells me the noise is from or around this area.

Will update when I get them pressed in

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amosfella

· #15 · Apr 16, 2019

Glad my suggestion helped you. It's a really nice write up.

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ezzo

Discussion Starter · #16 · Apr 16, 2019 (Edited)

ps2cho said:
Ok great thanks! I’ve ordered two new bushings.

I think the problem originated from the fact I mistakenly torqued the new arm when the car was not on the ground at ride height.

Right, FSM specifically states that suspension components must be torqued where the car is in a "ready to drive" position.

ps2cho said:
The arm replacement does not require anything special, disconnect the ball joint (lower) and lower strut forks, unbolt, and remove, that’s it.

Disconnecting the outer ball joint and the strut fork is not the issue. Removing the bolts of inner bushing of the wishbone is. Specific, I am referring to the "front" inner bushing where the bolt is hidden behind the sway bar (what you refer to as the anit-roll bar). Did you get a special wrench for that bolt. It is in a very tight spot.

ps2cho said:
The engine lifting you are talking about is for the anti roll bar removal. The FSM states it’s required to remove it, however even that you can get around if you grind down an Allen key

Right, makes sense.

ps2cho said:
I’ve ordered new bushings and will press them in and hopefully that’s going to resolve the issue! It started clunking about 10-15k after I replaced the arm and I’ve replaced the strut, coil, sway bar links, inner arm bushings (they were cracked and twisted already due to my mistake).

One thing I forgot to mention is that the bushing has small rubber nipples on one side (see first picture) that are not on the the other (second picture). I noticed that the OEM bushing was installed with the nipples facing towards the front of the car. Not sure if that makes a difference.

ps2cho said:
I feel like this is the problem finally and am very thankful your thread popped up and made me jog my brain thinking this has GOT to be it!

In addition, my chassisears tells me the noise is from or around this area.

Will update when I get them pressed in

Good luck. Awaiting your feedback when you are done.

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ps2cho

· #17 · Apr 17, 2019 (Edited)

ezzo said:
Disconnecting the outer ball joint and the strut fork is not the issue. Removing the bolts of inner bushing of the wishbone is. Specific, I am referring to the "front" inner bushing where the bolt is hidden behind the sway bar (what you refer to as the anit-roll bar). Did you get a special wrench for that bolt. It is in a very tight spot.

Good luck. Awaiting your feedback when you are done.

OK with you now -
There is just enough space to fit a 23/24mm wrench on the nut.

If you already have the camber bolts installed then you’re a little stuck because you can’t untighten it from the bolt end.

What I did to remove the camber bolts was to remove the sway bar. To remove the sway bar upper bolt that is partially blocked by the subframe is to grind down an Allen key. It’s fiddly but it worked for me.

With a non-adjustable Lower arm bolt it’s easy since tou just hold the nut with a wrench and loosen from the bolt-side

My bushing arrives next week so I’ll update in my “suspension knock” thread the weekend after next and then get to the dealer for a true alignment with fresh tires if this fixes the issue (feeling confident this time)

ezzo

Discussion Starter · #18 · Apr 17, 2019

Benzyle said:
The main bushing bolt can also be torqued if you use another jack to raise the steering knuckle up to normal ride height first.
Measure the distance from wheel hub centre to fender when sitting on the ground and later jack it up just the same.
This way the rubber is not twisted when the car is lowered to the ground.

This might work for the shock absorber fork. Although, I did it when the car was on the ground (there is some clearence). So, this may work for some suspension components, but not for all. Think about the sway (stabilizer) bar. the bar has to have the same pressure on bother sides before you torque the nuts of both links.
What you could do, is probably pull the front up on wramps and raise the car from behind to make it leveled with the front. This way, the car's weight is even on both sides of the front suspension components.

ezzo

Discussion Starter · #19 · Apr 17, 2019

ps2cho said:
My bushing arrives next week so I’ll update in my “suspension knock” thread the weekend after next and then get to the dealer for a true alignment with fresh tires if this fixes the issue (feeling confident this time)

Just to also be sure that you are aware of this.... Have you seen this video? Did you have to remove the nut/bolt of the sway bar linkage before? If you did and you did not replace the nut and bolt then the clunking might be from the loose nut.

ps2cho

· #20 · Apr 24, 2019 (Edited)

OK so my parts arrived today and getting started.

I measured my bushing and came up with 51.90mm in diameter. Was hoping one of my other MB bushing tool kits had a cup of the right size, but unfortunately none were remotely close.
I know you mention you used a 1 7/8" socket, however you did some damage. In your experience, would you have preferred a slightly bigger or smaller socket?

I have a 50mm bearing race, however I'm not sure pushing the internal rubber that far in, if even for a short period is wise.
Want to make sure I can avoid any damage to the outer shell...any tips from your experience? going to do some thinking on what else might do the trick. Don't own a 1 7/8" socket so either way have to buy something.

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