albertchampion

for several years, and 27,000 miles, i have been driving a 2006 cl500[46k total]. i drive it with the abc "on" in the "c" setting all the time. and i drive fast.

i have found the driving to be supple, stable. and quiet when traversing harsh road irregularities.

and i expected the same with the 2006 cl55amg that i acquired two months ago. but i am now wondering if the abc suspension has been set up differently for this vehicle. again, with the abc engaged in the c setting, i find the rear suspension is very noisy over even minor road irregularities. and it feels like, sounds as if the right rear is rebounding multiple times, noisily, over even minor road surface irregularities.

initially, i thought that the issue was one of cold fluids, since i first noticed the issue during our recent below freezing weather. and the noise and the harshness tended to subside after about ten miles of driving.

i mentioned this to my dealer dervice gurus last week when the car was in to correct what the selling dealer, sfbenz, overlooked in their cpo exam. my gurus, whom i have known for 3 decades reported that everything checked out.

and indeed it did seem to run like my cl500 over the last few days.

but....today i took it out, it ran just like my cl500. then i parked it on level ground, on asphalt, during a warm afternoon[80F] for about 20 minutes while i did some business at the county courthouse. returning to the car, driving away, i found the rear suspension to be once again unnaturally loud when thumping over minor road irregularities. it sounded as if the right rear was double-thumping. over 20 miles, this noise and this harshness seemed to dissipate.

is there a suspension issue here that the dealer's service tech missed? or does the cl55amg have a suspension that is noisier, harsher than the cl500?

all ears.

AMG055

The suspension for the AMG vehciles is tuned differently to non AMG. I don't have any insights for your problem. My AMG CL55 rides smooth at all times and the suspension is not caught out by any road irregularities irresepective of whether I am in C or S modes. The suspension has always been quiet and taken all road surfaces I have encountered in its stride.

saintz

What tire widths do you have on each car. That's probably a big difference.

The components are the same, but the software is different. The AMG model should be firmer (due to the way the software manages the oil pressure).

Does the car sit low at any one corner? If so, your dealer should have caught this.

mf219

I'm no expert, but I read in another post about what a user described as a harsh or "hard" ride. He claimed it was caused by a bad accumulator. Just a thought....

albertchampion

this vehicle is outfitted with the 19 inchers that amg/benz fitted as an option when the car was manufactured.

as i tried to say, this is a problem that seems to come and go. which leads me to think that there is a malfunctioning component somewhere. my ears tell me it is associated with the right rear damper.

when this phenomena is not present, i find no difference in the suspension performance of the two vehicles.

back to the dealer for closer scrutiny i suppose.

saintz

If you have 19" summer tires on the 55 and 18" all weather tires on the 500, that will make a big difference when going over bumps or expansion joints. It will also vary with ambient temperature and tire temperature (how long you've driven).

Are all tire pressures where they should be? How wide are the rear tires on each. Having very wide rear tires will cause squirm over bumps, but in a somewhat irregular fashion as you noted.

albertchampion

i am running the factory oe sizes on both vehicles. all seasons. cl500 is running the continental extreme contact dws shoes. cl55 is running michelin pilot sport A/S shoes.

perhaps you misread my issue. and that is the right rear on the cl55 gets weird from time to time. not all the time. as if the shock suddenly decides to malfunction. then clears itself.

and by the way, this happens in non-abc mode as well.

saintz

Weird?

albertchampion

yes, weird as in: one moment the right rear seems to be working properly, and then suddenly it decides to malfunction[as if a bad damper]. then as i said, it clears itself and seems to function normally.

and by the way, i am pretty good at hearing/feeling when aspects of a vehicle go south. i have owned enough benzes and still own and operate enough to notice when suspension components go south.

the dealer's ace mechanic did not discern any discrepancy when the vehicle was in his shop, but that does not surprise me, because whatever is going on is an intermittent bit of faulting. still my experience informs me that what may be intermittent today will be more than intermittent tomorrow.

saintz

Malfunction? What does it do?

albertchampion

it feels as if the right rear damper is bouncing[i.e., more than one response to rather minor road irregularies]. this is not happening with any other corner of the vehicle. also, when it does this, there is an unusually loud booming sound from the right rear that accompanies this.

as i said, i identified it as multiple[double] thumpings for what should have been an unnoticeable, unhearable traversing of a minor road irregularity. left rear, left front, right front traversed the same irregularity, no similar noise or sensation of uncontrolled damping.

does that capture the sensation for you?