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Transmission Mount Replacement
 
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Pelican Technical Article:

Transmission Mount Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$13 to $270

Talent:

**

Tools:

17mm, 13mm socket, extension, 19mm wrench, floor jack

Applicable Models:

Mercedes-Benz W123 (1977-85)

Parts Required:

Transmission mount

Hot Tip:

Put a piece of wood between the jack and transmission

Performance Gain:

Proper drive shaft alignment

Complementary Modification:

Check your flex disks

The transmission mount provides many functions; it holds the transmission in proper alignment with the drive shaft, absorbs some of the drivetrain vibrations and helps transfer the torque to the drive train. The mount is made of metal and rubber and the rubber section does wear out. When this happens the drive train will fall out of alignment and can cause damage to other expensive components.

One of the symptoms of the mount going bad is a sound when getting on or off the gas as the slip in the mount allows the transmission to flex in the mount allowing it to move around. You can also start hearing and feeling a lot more drive train noise.

If you suspect your mount is going bad, safely jack up the car and have a look at it. You can see it clearly without moving any other components. If you feel it is bad, place a piece of wood under the transmission and slowly lift the transmission. If the transmission moves by itself you have a bad mount.

To change the mount you will need to safely raise and support the front of the vehicle. Please see our article on safely raising and supporting your w123.

The transmission mount mounts by a single 19mm nut to the tail of the transmission (red arrow) and two 13mm bolts to the cross-member (yellow arrow).
Figure 1

The transmission mount mounts by a single 19mm nut to the tail of the transmission (red arrow) and two 13mm bolts to the cross-member (yellow arrow).

Begin by placing a piece of wood across the transmission to help distribute the load and safely support the weight of the transmission.
Figure 2

Begin by placing a piece of wood across the transmission to help distribute the load and safely support the weight of the transmission.

Use a 13mm socket and remove the two bolts holding the mount to the cross-member (red arrows).
Figure 3

Use a 13mm socket and remove the two bolts holding the mount to the cross-member (red arrows).

Next remove the four 17mm bolts holding the cross-member to the chassis.
Figure 4

Next remove the four 17mm bolts holding the cross-member to the chassis. Use care as once the last bolt is out, the cross-member will fall. There is a bridge late between the cross-member and mount (red arrow); do not lose it and do not forget to install it when installing the new mount.

Use a 19mm wrench (preferable geared because of the tight working conditions) and remove the single nut holding the mount to the transmission (red arrow).
Figure 5

Use a 19mm wrench (preferable geared because of the tight working conditions) and remove the single nut holding the mount to the transmission (red arrow).

You can now replace the transmission mount.
Figure 6

You can now replace the transmission mount. This mount is fine but if your mount is starting to go you will see, rips, tears, cracks and general degradation in the rubber.

Make sure to clean up all the contact surfaces to give you a good flat contact before installing the new mount (red arrow).
Figure 7

Make sure to clean up all the contact surfaces to give you a good flat contact before installing the new mount (red arrow). Installation is the reverse of removal.

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Page last updated: Mon 1/16/2017 03:08:13 AM