I had my rims fixed, new tires put on with the Hunter road force, Radius arm bushings replaced and car kept shaking when stepping on the gas. It turned out to be the fluid in the trans was contaminated and the torque converter wasn't properly engaging. I think the radiator was bad as the trans cooler is on it. Anyhow, that was replaced, all fluids flushed and it rides great. The noise from the torque converter is gone and no more shaking.

Wow I would never guess that

This really taught me something. I'm glad I bought the warranty option!

AMEN
I've just hit $25k in warranty work. I'm very picky.

What year C32? How many miles??? Thats scary to think about.

Its an 02' with 62k miles. Most of the cost comes from my intercooler cracking and letting coolant flow into the supercharger then the cylinders. I have a very good relationship with the shop where I take my car. Upon changing the intercooler they recommended to change the supercharger, change the oil and the oil pump. All that and labor amounts to about 6-8k. New parts too, which is fantastic because those are parts that eventually have to deal with wear and tear.

I also had certain parts replaced like new AMG seat covers because they "malfunctioned". I also helped my friends that have a C32 with parts that are somewhat costly. teehee <3 Carmax extended warranty.

Hahaha got it. THats cool you got the seat and friends taken care of.. via your car. The side bolster seems to show wear pretty easily. I have an 04, and the thought of contamination has me scared. Real scared. My c32 has been bulletproof, but I am still scared.

2004 with 59900 on it when it happened......... I'm just glad Mar was able to
figure it out over at Mar Automotive in Manassas, VA. Great shop to deal with and
that's where I'm taking it from now on.

I am so glad you posted this. I have an '04 with 58k on it and seem to be having the same issue. I took it to the dealer and they said the ESP sensor went bad. They replaced it and the vibration continued. I had read on another site the CV joints are not the best on our cars, they leak and it somehow gets into the drive shaft and warps it. I was thinking that was my issue until I read this.

Glad to help someone else out. This took a long time to solve but glad it's dealt with.

Was this a moderate shaking while cruising at moderate speed that got worse under light acceleration and almost felt like a warble or slight surging / drag on the car by chance? Also, did the car make a noise while accelerating gently but firmly while cruising in top gear (almost sounds like you're driving over a bridge or scuffed pavement)?

The shaking was more noticeable while stepping on the gas. However, I noticed it at highway speeds as well- that's why I thought it was the wheels or suspension or bad roads.

I didn't notice any surging just a thumping feeling felt within the cabin and no real noise either.

I'm glad my local mechanic figured it out in like 5 minutes of driving and the dealer didn't catch it.......

I have this problem happening also. I feel it more than I can hear it. Just a slight vibration. Usually around 40 mph under light throttle. What's the first thing I need to check?

Sounds like the same issue I had. I'm not sure how to check it but my mechanic told me the trans was contaminated and he had to replace the trans cooler on the radiator/radiator then flushed the system out. No problems since then. Is there a way to check the trans fluid? If so, maybe it can be tested. I leave this stuff to my local mechanic since my warranty doesn't run out until I hit 100k miles.

If left uncheck, how long before this contamination really lets you know. i.e. failure or serious shaking?

Mine took 2-3 months and just got worst. I simply knew I needed someone to fix it. Started small and snow balled in 2-3 months.

Mine started a long time ago, I suspect, with an intermittent hard shift. Over the last week I thought it was bent wheels. It spiraled up to very serious sounding in like 25 miles of driving.

Does anyone here get a slight vibration when sitting idle at a light? It only happens for a second then stops.

i'm starting to get that now... but it only happens when it's below 30F degree outside.

I have had minimum shaking on both C55 I had. Didn´t get worse after all but was temperature sensitive as well...

Check engine / tranny mounts..

The vibration on my c32 at idle almost seems like a misfire, but no codes are stored. I agree that the engine and/or tranny mounts would be the likely cause. I do however, find it strange that it's not a constant vibration, but feels more like a misfire on one cylinder? Thinking I could possibly have a leaking intercooler. When the engine is cold, and I'm accelerating anything into boost it feels like a wobble. Once the engine heats up some no more wobble feeling. I do notice a slight vibration accelerating, but am hoping the transmission oil just needs to be changed (high mileage), and it's not contamination... I would have to say too that I started noticing these issues when winter hit. Definitely temperature has an effect.

I am having this problem right now. The car shakes under partial throttle and once you let off the gas, it shakes when coming to a stop and you can feel the downshifts as it shakes. It would not downshift, so I thought it was the gas pedal and I replaced it. However, while the new gas pedal helped a lot, the car still shakes and jerks like crazy under partial throttle. I just wonder if it is possible that my transmission is contaminated with glycol although it was replaced around 2 years ago and about 18k. The car is very jerky and extremely uncomfortable to drive. I have new NGK iridium spark plugs, k&n's, and a CM30 IC pump. I am out of warranty, but thinking of taking the car in for a checkup or do a torque converter/gear adaptation to see if it helps.

I wonder if this is what's happening to my car

Yep I have this problem now and I was told my engine mounts were bad, a little expensive though so I put it off also my siren just went out so I have to get that done too. The car just start chirping loud at random while driving.