Ausmbtech

A few weeks after my last track day my C43 started steeping the back end out under acceleration. Having had a bit of a run on damaged torque arm bushes I just parked it until I had some time to get to it. Yesterday I finally had some spare time and found something that I certainly wasn't expecting.

It has somehow managed to bend BOTH torque arms in exactly the same way. I've seen plenty of worn bushes but NEVER a bent arm other then due to accident damage. I was intending on fitting a set of aftermarket arms but decided not to until I work this one out.

Has anyone else ever bent a rear torque arm? I cant imagine it's due to the 55 conversion, I've also got a W210 E55 with over 200k kms with the original arms and it doesn't have a problem.

Any thoughts?

cm60k

If bushings not got loose, it could be something happens to axle bearings or diff. mounts or diff. interior bearings/gears went bad..!!

ZAYED,,

Super B

Wow aus, that's crazy!!! It's hard to believe... Any chance some body shipped your car at some point and they chained the car at that point?

One would think the tires would break loose before making the kind of forces to do that. Pretty impressive

Sulaco

holy crap I think this is what I've been chasing with my C43! the rear end is doing the same thing and I didn't even know to look for this!

Super B

Hey aus what springs are you running? did you bottom out real hard at the track? camber bar looks good? Like you had said.. Short of an accident/impact what a crazy thing to have happen.

Ausmbtech

I've got a new set of arms in now and I'll see how it goes.
I certainly hasn't been towed, had rear end accident damage and hasn't had any particularly hard bumps since the arms were last replaced (due to a single damaged bush but I replaced the pair of arms)

The springs that were in it were the H&R sports but I've now changed back to OEM with size 3 spacers.

All W201, W202, W203, W209, W124, W210, W170 use the identical arm with the exception of some W210 wagons (aluminium arms) and the CLK63 (I think only due to a track width change).

Some arms in the rear suspension were upgraded for the armoured version of the W210 but not the thrust arm so MB obviously didn't think it was a weak spot.

My best guess is that although there is nothing advising they need to be installed in a particular direction that they may indeed have different load capacities depending on the direction they are installed. Whilst this wouldn't be an issue on most models (good luck breaking anything in the drivetrain of my 190D due to excessive torque!!!) it may be an issue on the higher torque models. I made sure they are mounted the in the same direction as originally fitted.

Whilst I don't believe this will make a significant difference, I don't have any other ideas at this stage.

Sulaco

You have an awesome collection of baby MB's. I had to fight tooth and nail to keep both my C43's when we got the wife a new Jeep Compass. I doubt she'd ever let me get a nice 190d or 240d as a third car, let alone a freakin' E55.

sick430

Hey Aus, I am having the same issue. When letting off after hard acceleration it feels like the back end (at least body wise) is stepping out to the right.
Was this the feeling you had? Will put the car up in the air this weekend. I have upgraded camber arms.

Ausmbtech

Most of the time if the back end moves around under acceleration and deceleration it usually the inner bush on the thrust arm. It's not worth replacing the bush alone, just replace the arm and I suggest doing both sides at the same time.

sick430

Thanks!!!!! I'll look onto that!

Ausmbtech

So I did a little digging through the MB "part bin" (EPC) and took a gamble on ordering a set of arms from a CLK63 as the 209 chassis had the same arms for all variants except the 63. They were about $60ea.

Looks like AMG knew they were too weak for track work too. I'm starting to think it's not the engine power that caused the damage but the cornering with a set of wide semi slicks because many people have done the same engine conversion without having an issue.

Here are some pics of the AMG thrust arms. (A209 350 0006)
They also use the harder bushings from the W210 wagons, there is more rubber in the bush compared to the stock bush as pictured.

KJI3jflarryfe93

did you test fit these thrust arms on your c43 yet?
let us know the outcome.

Ausmbtech

There are identical length as the factory arms, they should be a direct fit......I'll let you know when I fit them next week.

DRBC43AMG

Just picked up this thread. Wow Aus looked like some serious problem and I immediately thought that knowing you tracked your beast, the use of slicks or semi-slicks could be the root of the problem. This was confirmed in one of your later posts.
Nice to know that an upgraded reinforced AMG part exists. I'll be thinking of this should I need to change mine one day.

cm60k

Great find Aus., this definitely will help widen curving wheels/tires as well..-

ZAYED,,

KJI3jflarryfe93

these thrust arms will they improve handling on public road?

DRBC43AMG

Seeing that the end bushes are beefier, I imagine that it should firm things up nicely. Now, I wonder if a normal butt dyno would feel a difference on normal roads. I doubt it very much.

Ausmbtech

I'm doubtful you'd feel any difference, it's just purely a reinforced control arm. If you changed the bushes in all the control arms to nolathane you'd notice though.

Pagz

Awsome find on the arms, look forward to knowing if they fit well Id definitly run these when mine are due!

Do you think you could weigh one before install?

Cheers,

sick430

Ok, I need these. will be ordering them shortly. Please let us know how they fit once they are installed.

sick430

any update? how do you like them?

Tony_AMG

Going to be very honest cause it happened to me on my c230 kompressor exactly. that only happened to me when i make a sharp turn and end up hitting the curb. you can be parking and can do the same thing. These arms are meant to bend easier than the rest but save the knuckle and other components as well. I have both in my kompressor that are bent exactly like that but are able to adjust the other arms to pass alignment too. also can be due to running potholes allegedly, but IMO experience is because of the curb bumps we do alot. have you had any wheel damage before on the rear wheels?

Ausmbtech

I've fitted the arms and done another track day. As I thought, you don't feel any difference in the car. They are a perfect fit though. I tried to confirm which way they should be installed (they are curved) but I couldn't find any pics of them fitted and no CLK63's are around when you want to stick you're head under one when you need one. I went with what I thought was right but will advise if I find they need to be mounted in reverse.

I don't believe the old arms bent from any kerb damage either on or off track. I've done at least 15 track days prior to the engine swap with no issues other than the rear sway bar mounting points breaking with is inevitable especially with a 4mm larger rear bar. If anything I use the kerbs a lot less on the track now with the engine upgrade as I don't feel like the need to "wring it's neck" as much in the corners to get some speed out of it. I've seen enough accident damaged arms to know it's rarely just one arm that bends and certainly not identical on both sides.

I have read that the CLK Black Series guys are having issues with the rear end feeling vague and loose under full power or on the track with slicks and their solution is to fit nolathane bushes to all the arms (Weistec do a kit). I don't like using nolathane unless absolutely necessary as it's still a road car so I'm going to hold out until I try using the "square" tyre setup (running 8.5x17" rims with 245/40/17 front and rear rather than a staggered setup) and then decide if I need to do this too.

DRBC43AMG

Thanks for the update Ausmbtech
Interesting you idea of going "square" with 17" Should improve understeer and braking with the larger front foot print.

sick430

i have gone 245/255 in order to curb understeer and braking and made a huge difference.

thanks for the info.