06cls55amg

alright so ive replaced both front airmatic struts with known good ones, and both rear shocks. EVERY front end suspension wear item is new as well then had alignment done as well as front tires dismounted, rotated and balanced . thru some wurth hhs on sway bar bushings as well, and new engine mounts.

The problem with my car is that on the highway especially after 80mph and under hard acceleration the cars body starts to sway left to right..... the faster i go the more violent it gets.

im officially out of ideas other than possibly bad sway bar bushings? car is lowered an inch via star ( shows no faults for airmatics either). seems to be getting worse instead of better even after all these new parts.

latemodel21

despite the similarity between the name of your symptom ("swaying" at speed under acceleration) and the name of the component(s) (sway bars), there is no relationship here. Sway bars (or anti-roll bars as they should be called) are a roll-couple distribution solution .... and have nothing to do with swaying at speed (unless you run over a pothole or bump, then your sway bar could introduce a momentary (singe event) sway).

If your issue is only under acceleration, you may want to look closely at any and all suspension components that locate the rear axle to the car (control arms, etc). Any worn or sloppy bushings here can change your alignment dynamically under acceleration (this is actually something we used to manipulate in circle track racing to get through the corners better ... but you just want the change to be as close to zero as possible for the road and road courses)

hope that helps,
Chris

PeterUbers

You didn't mention the status of the tires and what kind they are

06cls55amg

ive already checked the rear suspension components with a pry bar i dont see anything that has excessive play, as well as grabbing the tire and doing the 9-3 12- 6 method everything is stiff as can be. the car launches and goes straight as an arrow otherwise.

the amount of left to right body roll when accelerating over 80 + is pretty significant.

how does one correctly check the rear suspension components for wear?

06cls55amg

michellin pilot super sport rears 295 30 20, Nankang ns20, 255/35/20 brand new 5k miles

latemodel21

Sounds like you have looked this over pretty thoroughly.

A couple of bits of info that might be useful here are ... how many miles on the car? and how did this first appear? (gradually? after you lowered it?)

You may want to return it to stock ride height (temporarily) to rule that out as a contributor.

In a perfect world, you could strap this on a chassis dyno and look at dynamic suspension changes, but short of that....

I would have your alignment/suspension guy ride with you in the car and demonstrate the problem to him. He/they should be able to inspect your rear suspension components (and re-inspect the front) and sort this out. If He can't find it ... you may need a new alignment shop.

Hope that helps,
Chris

HeissRod

Agreed

06cls55amg

wannn say after my strut blew out last year, thought that the replacement strut had a bad shock or weak bag, but the 3rd strut is doing the same thing. as i have mentioned earlier replaced the rest of the airmatics as well to rule them out.

when my strut blew the car was slammed, since then i have raised the car but still dealing with this issue. idk going to throw my stock front wheels on and see if these nankangs are the culprit as this guys seemed to have a similar issue.

my issue seems more in the suspension though, as the tires feel planted to the ground, its the body that sways left to right.

http://www.amazon.com/Nankang-Noble-...l&pageNumber=1

Forrest Gump 9

Check your alignment, especially your toe.

06cls55amg

this is what they printed out for me

O-55

Does your car also sway when decelerating?

06cls55amg

no, just at higher speeds and only under acceleration does the body seem to rock left to right. the last time i had this happen was when i was over taking some slow cars, noticed it was starting to rock side to side, let off , got back in in no change. the faster i went the faster and more it rocked, once i passed the cars i let off completely braked, and the car went back to normal.

1ForcedBenz

Have you replaced or checked the rear shocks? Not the bags but the actual electropneumatic shocks?

HeissRod

How is your trans mount? What about your rear subframe mounts?

O-55

Who installed your front thrust arms? Are you using camber bolts?

06cls55amg

1ForcedBenzon 2nd set of rear dampening shocks. 0 change

HeissRod, Brand new motor and trans mount. made 0 change

O-55 i changed everything my self, yes camber bolts.

NO change after all new front end components and alignment, i basically just replaced parts that were good. only the upper control arms bushings are original.

i had the car sitting even lower for 8 months or so and had the car well over 140+ and never had this issue. i want to say my issue presented it self right after the drivers front bag blew in my garage.

sucks cause i love the car but it drives like ****

O-55

I would verify that that the bolts are secured between the lock tabs of the bushing. There is a notch on the bolt head that will either point towards or away from the wheel when correctly inserted between the tabs. Same goes for your lower control arms.

06cls55amg

ive had this problem way before i replaced the original parts with the new camber bolts etc etc. the lower controls arms i pushed in towards the engine and made sure the grooves of the camber bolts went into the 2 tabs in the bushing before i tightened the nut.
i only recall the control arm bushings having these tabs...

O-55

The thrust arms have them as well.

latemodel21

I don't have any real first hand with airmatic, but I've tussled with ABC a bit.

I don't have a clear understanding of the symptom, at first I thought that you were suggesting that the tail wags, but now I think you are saying that the car (or front) rolls left and right (as if it is raising one side and dropping the other and then switching).

In any case, it is odd that the occurrence seams related to speed and acceleration. Have you looked at the inputs to the airmatic itself (perhaps starting at the level sensor near the bag that blew)?

considering that the airmatic system has 3 lateral acceleration sensors perhaps one is acting up with strange results? I looked at the wiring diagram to see if some or any of the sensors may have common power, ground or signal lines (for instance, +5vc dropping out of both front level sensors for a moment might make one side drop while the other raised depending on the configuration... BUT, no luck there as EVERY sensor is individually/directly wired to the airmatic controller) .

I assume the star tester shows nothing unusual.

you may want to try wiggling/tapping the sensors and their connectors (that you can reach) while the car is running and on a lift (that loads the tires ... muffler or alignment rack).

you have a real head scratcher there.


Chris

StarvingArtist

I had a similar problem when I reduced the rear toe to 0. There is so much flex in the rear suspension it would toe out under acceleration and the car would sway back and forth pretty hard. Too much toe might stay straight under power, but sway at speed.
I built a wooden jig to do my own alignments, but you can play with it a little using a straight edge.
Put some masking tape on the side of the car with an x, lay a straight edge across the middle of the tire and take a measurement in to the x and write it down. Then reduce the toe a bit on each side. See if it helps. It's kind of a pain because you can't measure and adjust at the same time. If an alignment shop is convenient, you can just have them set it were you tell them. Lot of words, but that is what I would try.

Roverron

I have the same issue please post what you find.
CLS55 I thought it was motor mount and then transmission mount, then sub frame bolt.

HeissRod

His alignment values show he is still running some positive toe, right in the middle of factory specs.

06cls55amg

The more ive been driving the car been trying to pay attention to what the rear does around bumps , road imperfections, etc. especially considering the front end is pretty much brand new.

One thing ive noticed is going around the off ramp where there is fractures/cracks in the pavement that go across, seems like the front wheels stay planted but when the rears hit that the car kind of buckles, and mimics the body roll issue for a split second just no where near as bad. not sure if this makes sense.

all 4 subframe bolts are in tact and used a pry bar in between the subframe and frame to check if there was any significant play already as well just in case anyone was curious.

this is a town fair tire wholesale account alignment... seriously considering bringing the car to a indy shop that my friend recommended me and have them take a look at it. im running out ideas and am frankly sick and tired of buying and replacing parts on this car.

latemodel21

Does changing from "sport" to "comfort" have any affect? How about changing select-able ride height?

I was also just thinking about how this happens to the greatest extent at higher speed (above the speed the car automatically drops to a lower position I am assuming) ... I wonder what your rear toe-change-curve is (relative to ride height) ....

Taking it to a recommended shop (as your friend suggested) sounds like a good idea.

hope you sort it out soon!
Chris