Fellow members,

I have been experiencing some drivetrain issues in the past few months and wanted to share a picture of my old and new transmission mounts. I had read in another thread (not sure where exactly) that it's not always possible to tell if a transmission mount is bad just by looking at it. This might be the case in some cases, but not in mine. Attached is a pic of the transmission mount I removed on the right, and the new one on the left.

My car is a 2009 model with 50.5K miles. I began hearing a faint but annoying whining sound at around 40K miles and had no luck isolating the sound with a mechanics stethoscope. Convinced it wasn't coming from the engine I began to fear the transmission, ABC system, or one of the other ancillary systems. Then at around 43K miles I began feeling a drivetrain oscillation/vibration/shift between 2000-3000 rpm. It was subtle, really subtle at first (my passengers said I was nuts) but I felt it was getting worse. It would peak between 2500-2800 rpm as I would gingerly accelerate through this range. After several other forum members had discussed/diagnosed similar issues I went ahead and bought a replacement unit. I researched prices at all the usual joints but ended-up getting it from Amazon the cheapest ($36.31 with free shipping):


Manufacturer: Lemforder (which i'm told is the actual manufacturer of the OEM part)
Part number: A 2212401018


As you can see in the picture, the old unit was completely sunken within the housing. Pulling and twisting the central, supported section wouldn't offer immediate indication of a failed unit (it was still very rigid) - but under the weight of the transmission and the application of torque its a different story. My lesson learned here is that time, just like mileage, has a strong erosion effect on such rubber components (mounts, bushings, etc...). My car only had 34K miles when I bought it in June 2016 (I have a long commute - hence the 16K miles in 9 months), but very quickly the daily use compounded the work already done by this unit in supporting the transmission for 7.5yrs.

Changing it was a breeze. Jacking the car up high enough to get under and work comfortably was a pain in the a**. As will be putting the two under-body panels back on unassisted. I will report back with a driving update later in the week as the car is still on stands in my garage awaiting a transmission flush/service to be completed - awaiting a new torque wrench to be delivered so I can finish the job. Long story.

Thanks to everyone on here for the great posts and for showing me that with research and patience - anyone can work on their AMG.

 

It's nice to see someone post back about findings.


Filled the engine and trans mounts in with a medium stiffness polyurethane, hopefully this will prolong the life.
Trans mount is lemforder
hopefully putting theses in soon and doing a write up

 

Wouldn't the urethane just serve to transfer vibrations back to the chassis?

 

Yes you are correct.

I am not super picky about vibrations especially if I know where it's coming from plus with my added power I don't want to be changing out mounts all the time.
I will report back about difference between stock

 

Good points. Let me know how it turns out. Very interested to see your results.

 

Also very interest about your results

 

Well finally changed the trans mount and no difference was made at idle.
I don't think I can really feel any change except in manual mode holding around 3k rpm, doesn't matter which gear, and floor it. What I thought was the clutch taking a moment to engage is gone. I'll report back in a few days if I notice anything different.

The mount I put in was filled with polyurethane there is a picture early in this thread.

 

I changed out my transmission mount last week as well. Big difference in my case as the original mount was collapsed. I used to have a lot of driveline noise and vibration in the cabin. Most of that is now gone. There's still a bit of noise and vibration, but that's due to a collapsed driver side engine mount which will get replaced eventually.

 

Replacing my engine gear mounts tomorrow. Hopefully some metallic sounds go away. I have some vibrations from the floor which feel metallic. Will report back with results.

 

After some daily use under a variety of loads there is some vibrations to the rear wheels.

3000-4000 rpm in lower gears with no throttle results in vibration not crazy but noticeable

Turning 90* from a stop at 40% throttle gives slight vibration.

The engine sounds better in my opinion due to the amplified sound from being more "connected" to the chassis.

Under normal daily use, not getting on it, you would not notice a difference.

 

A couple of thousand miles ago (~70K miles) I began feeling the same annoying vibration when cruising at highway speeds between 1500-2800 RPM. Suspecting the exact same culprit as the last time I felt this (the transmission mount) I decided to order a new one and remove the old one to inspect. Sure enough, upon removal there was evidence of failure in the unit I replaced just 22K miles ago:



LEFT: Installed new at 50K Miles (20K miles in service) RIGHT: New unit installed 6/24/2018

If you compare these two to the ones I originally uploaded when I replaced the first unit at 50K miles you can see the same sagging of the bushing/supports, which is causing the rotational imbalance that leads to the annoying noise/vibration.

I wish someone would produce a high performance model of this part, with a superior/stiffer medium, less prone to sagging.

The only good thing about this repair is it's easy to do, just 5 bolts - and the part is cheap (< $40 online). Including jacking up the car, removing the underside shielding, and swapping out the unit is under an hr if you have all your tools ready. For anyone considering this please be warned that you MUST support the transmission (and be able to adjust the height of the rear part of the tranny to align the new part - use a block of wood and a bottle jack) - the last thing you want is the transmission to torque on the engine side as it tries to sag on the rear.

Hope this helps anyone experiencing the same issues.