Restortion Article: 1982 123 Chassis 300D Suspension and Final Drive Repair

While the car is getting ready for the engine transplant, I have decided to go ahead and start on the suspension and final drive restoration. This phase will include the front suspension, rear suspension, drive line and rear end. Once again, my goal will be to replace all common wear parts and components even if they might "look ok." As these beloved 123s get older, we are finding an increasing number of problems showing up in these areas. Even on low mileage cars we are seeing numerous failures related to any and all rubber parts. Contrary to popular belief, an older Mercedes diesel will not go forever if it is not maintained. Since I come from an aviation background, I would much rather perform preventative maintenance than fix it after it breaks.

With the engine and transmission out of the car I will remove and inspect the drive shaft assembly. You don't necessarily have to remove the drive shaft for inspection but it is easier to check the condition of the center bearing carrier and universal with it on the bench. Since I have to replace the rear flex disk, I might as well pull the drive shaft now. Normal wear / failure components on the drive shaft include the following:

• Front and rear flex disks
• Rubber center bearing carrier
• Center bearing
• Drive shaft centering bushings
• Universal joint

Wear in any of these areas can lead to excessive drive shaft vibration and noise. Failure of the flex disks (particularly the front) can lead to the transmission locking up while driving and even permanent transmission damage. For those reasons the flex disks will automatically be replaced along with the center bearing carrier. The universal joint and center bearing will be carefully inspected and replaced only if needed. WARNING: While working on the drive shaft, never remove the two halves without carefully marking their positions to each other BEFORE removal. The drive shaft is balanced at the factory with the two sections together. Changing their position to each other can lead to excessive drive shaft vibration.

To be continued ...