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Pelican Technical Article:

Transmission Mount Replacing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$100

Talent:

****

Tools:

Set of sockets, 13mm, floor jack, wood blocks, 13mm wrench, wheel chocks, safety glasses, torque wrench

Applicable Models:

Mercedes-Benz E320 (2003-09)
Mercedes-Benz E500 (2003-06)
Mercedes-Benz E55 AMG (2003-06)

Parts Required:

Transmission mount, fasteners for the mounts (if needed)

Hot Tip:

Work with a cool exhaust

Performance Gain:

Smooth driveline

Complementary Modification:

Replace driveshaft flex-disc at the same time

The transmission has a large rubber mount that insulates it from the aluminum support bracket. The rubber mount has fastening points, bolting to a bracket (usually supplied with a new mount) to the transmission support bracket (cross member).

The mount wears over time and cause a driveline vibration. Sometimes if they fail catastrophically, there will be a clunk when accelerating. When inspecting the mounts, look for dry rot and cracking. You can check to see if it has separated by jacking the transmission. As you jack the transmission, monitor the mount. It should stretch a little but stay in one piece. When replacing the mount, I'd suggest inspecting and replacing the fasteners if needed. You are not required to replace them, but I always feel better about having a new fastener, especially on something that takes as much stress as a mount. It's also not a bad idea to replace your driveshaft flex-disc at the same time. It is also made of rubber. If the mounts are worn out, the flex-disc can't be far behind.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

In this article, I'll go over the steps involved with replacing the transmission mount.

The two rubber mounts are the same part number, located between the transmission (red arrow) and the aluminum support bracket.
Figure 1

The two rubber mounts are the same part number, located between the transmission (red arrow) and the aluminum support bracket.

Place a screw jack or hydraulic jack under the transmission with a wood block (red arrow).
Figure 2

Place a screw jack or hydraulic jack under the transmission with a wood block (red arrow).

Working at the transmission-mounting bracket, remove the 16mm fastener (red arrow).
Figure 3

Working at the transmission-mounting bracket, remove the 16mm fastener (red arrow). Then remove the two 16mm transmission mount nuts (green arrow). While supporting the mounting bracket from below, remove the six 16mm bracket fasteners (yellow arrows). Be sure to support the bracket or it will fall as the final fastener is removed.

Remove the transmission-mounting bracket from the vehicle.
Figure 4

Remove the transmission-mounting bracket from the vehicle.

Working at the transmission mount.
Figure 5

Working at the transmission mount. Remove the four 16mm fasteners (red arrows). Be sure to support the mount as you remove the final fastener, as it will fall away from the transmission.

Once the fasteners have been removed, remove the mount from the transmission.
Figure 6

Once the fasteners have been removed, remove the mount from the transmission.

The mount is attached to a metal bracket.
Figure 7

The mount is attached to a metal bracket. This bracket is supplied with the new mount, no need to separate the two. In the future a mount may become available without the bracket, if so, you would have to cut the securing strap (red arrow). Then remove the 166mm nut (yellow arrow) and transfer the bracket to the new mount. When installing the new mount, be sure to install all the fasteners to the transmission evenly before the final tightening. Then, install the support bracket and tighten all of the fasteners for the transmission support bracket.

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Comments and Suggestions:
Coop Comments: Your site is very helpful! When doing the 2003 SL500 it will be a bit different? But is the process the same as described? Thank you.
March 2, 2017
  Followup from the Pelican Staff: Yes, it is different. We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
SDBob Comments: Thanks for the great information. This was a super easy fix, thanks to your tutorial. I was hoping it would drastically help the shaking and vibration, however it 's clear now the vehicle needs new motor mounts.
June 22, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Jonathan Gao Comments: First of all, this web site really helpful. The instructions are clear and simple.

I have a 2004 E320 Wagon. The transmission mount and the support bracket are a little different, but I was able to replace the part following the instructions. The photo of the bracket is attached. It has 6 nuts for mounting the bracket, and 2 nuts connecting to the transmission mount.

I could only support the transmission under the transmission fluid tank. I used a big piece of wood to distribute the weight. It was ok. I was not quite sure about the tension. I stopped when I start to feel tension when jack it up.

February 28, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 

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Page last updated: Tue 11/21/2017 02:48:42 AM