No, its usually the ball joint that gives out on the W201 and W124 due to wear, age and sometimes rust. The W202 C class and W208 CLK built during MB's rusty era (late 90s early 2000s) suffer similar control failures as the W210


The inside of the the control arm is always more rusty than the outside making it damn near impossible to inspect. I think water, dirty and salt get trapped inside the outer end of the control arm. All the failures are concentrated in the northeast (NJ, CT, NY, MA, OH).

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CENSORED due to not family friendly words

This doesn't make any sense. Welds are coated just as the rest of the part is, so it isn't an issue of bare metal. And welds are stronger than the material surrounding it.

Metal fails NEAR the weld, as it did in this situation.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

On my 124 control arms, there is a drain hole at the end. Is there a drain hole in these control arms?

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Best preventative is to mix up some hot grease and oil and spray into closed cavities. If for example a part is fabricated by welding and not coated quickly.Existing rust that forms locally after welding gets coated over and continues to oxidize if oxygen can reach it. Nothing I can really think of stops existing rust or restored the unrusted strength other than replacement. At the same time petroleum products really seem to slow it down. Thats if they can reach and saturate the rust. The protective shield they present blocks oxygen or the vast majority of exposure to it.

We scrapped an excellent later 126 gas car simply because the rust had gotten too established in the suspension mounts etc. The car was a fairly low milage example as well. Actually the body and interior in general still looked really great.

lmao @ everyone jumping all over the OP as if MB still makes cars to the standards of quality they did in the 1950s

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1981 NA 300D 310k miles

In the old days ( pre 80's ) car bodies rusted rapidly, engines / transmissions didn't last very long. Frames sort of lived only due to their thickness.

Now cars last much longer and parts the previously didn't fail are now wearing out. Kind of like since people live longer, all sorts of new illnesses have popped up in old age.

If the lower ball joint is seizing up, it will translate a bending load to the control arm. Since the end of the arm is a great stress riser, it will break there.

Grab the ball joint stem with pliers and give it a flex, it should move with some resistance but not a struggle.

Agreed, I wasn't saying the weld fails, I was saying the metal near it fails. Apparently im not good with expressing my thoughts.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Metal oxidizes when welding starting rust.

Paint usually does not flow so well into the groove between the metal and weld bead.

Welds are often rougher than sheet steel so paint does not cover so well.

17 year old car in a snow / salt area. Don't blame the manufacturer, things wear out.

The problem IS with the design. But not just the W210, but also other modern cars, have had everything lightened up. On the W210 (we own one) the poor spring perch is a well known fault. Another is the beam that runs across under and near front of the engine. It is very lightweight and formed out of sheet metal. The plastic undercovers trap water and the beam sits in it. I had corrosion on that beam. Under their Goodwill program, MBCanada had the beam replaced for me (Several thousand $$ job)

Those control arms with corrosion on inside, likely look perfectly OK on outside. Ours (and the rest of the car) get annual external rust treatment. But inside, metal may be getting thinner and thinner. Eventually you hit a bump and it fails. When designing mechanical parts, designers should provide metal thickness required by design+safety factor+corrosion allowance. Perhaps they didn't think the metal would corrode from inside where it is not exposed to environment?

We have discussed W123 rear control arms before. I have one that is partly corroded. I drilled a few holes near top and sprayed in Fluid Film and then installed removable plugs in holes. Still OK but always a concern.

Sounds like our E320 control arms may need same internal attention?

On the positive side, after 17 years, we haven't had a failure on W210 suspension. Fingers crossed!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

There apparently never was a recall as such for the 107s, but there was an agreement to repair subframe 107s delivered to USA (and Canada).

If that is what you are referring to, it seems it was for the control arm subframe mount, not the control arm itself.

At this stage, without large numbers of control arm failures, MB would not likely issue a recall unless forced to.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

W210 spring perches........control arm failures.......what's next? Geeesh!

Both these item/areas could have been constructed with air-frame style machined aluminum, right?

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'06 E320 CDI
'17 Corvette Stingray Vert

Are you able to access the repair and replacement parts history of your car before you bought it? That information may prove valuable to you with the investigation, forensically speaking that is.

Good input, 97SL320.

I thought there'd be related parts culpabilities to examine, that POSSIBLY could be related to a control-arm failure.

..........Qs that may be helpful in forensically finding POSSIBLE causation here........

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'06 E320 CDI
'17 Corvette Stingray Vert

Thats an interesting point of view there.

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CENSORED due to not family friendly words

Should I be replacing both control arms ? I am doing both springs but is it necessary to do a pair of control arms as well ?

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2003 GX470
1998 E300 3.0TD
2002 Dodge 2500 4x4 cummins
1998 Dodge 3500 5 speed Cummins

I doubt that it is necessary to do both. But if one failed, perhaps other will not be far behind. If it was my car, I would do both.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5