Noturgrandpas63

Hey guys!
Quick question- I'm fairly new to AMG although not new to the car scene. I have a vibration in 7th gear when under very light load, say speeding up from 65-70. OR when I start going up a very slight incline.
Now the tricky part- I can see RPM's visually fluctuate, but only, maybe 200 RPM. (When RPM's fluctuate is when I feel vibration.)
The car still hits/downshifts just fine, no vibration.
When I drive in M, and keep RPM's right at or above 2kRPM no vibration and hits just fine.
Driving around town the car is wonderful and fun!
It is a 2011 C63, 68k on the dash; I have read about the headbolt issue and have verified the engine number with multiple dealers so as far as I know, without cherry picking the engine, headbolts should be fine. I have also had MB of Westminster in Co put their hands on it, drive it, inspect it, and they said "it's a beautiful car- nothing to worry about"🤔
I thought I read somewhere something about a solenoid in the transmission that may need to be replaced? Anybody else hear anything about this?
Fhank you for your time in reading this, sorry it's so long just wanted all the details in one place.

Black_Mercedes

Does this happen when driving on the freeway if you left off the gas the RPMs drop 200?

Mort

Sounds like your torque converter unlocking and revs going up a bit because of it, as you apply a slight load.

Noturgrandpas63

This happens as I apply throttle to speed up slowly. It's very weird.

Noturgrandpas63

Interesting- Makes sense to me. Would you suggest a "burnt out" TC? I'm thinking I used the right terminology for a faulty TC. Because I also forgot to mention I can sit there and rev the engine to all RPM's and and the thing feels and sounds amazing. Just seeing if anyone else has experienced anything like this 🤷‍♂️ Like I Said dealership didnt find anything. Motor mounts are fine, absolutely nothing.

Mort

I think the transmission has adapted to how you drive the car.

blay127

Anybody else have this issue or a resolution? I did shortly after i bought my car with 76k miles on it. I changed the trans fluid and filter and symptoms went away (FCPEuro Pentosin kit for trans with A89 code. My 2011 has that). I have put about 10k miles on the car since then and the vibrations have come back and worse than ever. I can feel it in 4th and its progressively worse in 5th, 6th, and 7th. Anything more than super light throttle in 7th shakes the car.

Any help is greatly appreciated. Thinking i might be looking at a rebuild, but maybe its a valve body issue. Thanks

BalanBro

Have you checked your driveshaft flex disks?

blay127

i will certainly take a look but i would expect that to cause issues in all gears, especially 1st and 2nd, wouldnt you?

BalanBro

The driveshaft spins faster at higher speeds. A worn flex disk could lead to imbalance at higher speeds. That makes more sense to me based on the vibration increasing in the high gears (speeds).

There might be more actual deflection at the lower gears due to higher torque, but it may not be spinning fast enough to cause a noticeable vibration. Kind of like a tire imbalance that you only feel at highway speeds.

NZ-Merc

Hi,
Try resetting the throttle to see if that makes any difference.
The other thing have you been through the basics like replaced the spark plugs and air filters etc.

By the way really nice colour I like it a lot.

jaronbenz

what would that be? That’s exactly what I have, 7th gear, let off the gas, and heavy vibration occurs

Noturgrandpas63

Thanks! I've changed it a bit since. Vibration is still there and had the transmission serviced about 15k miles ago now. Went away for a bit but now its back. Thinking it is a torque converter issue.