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Pelican Technical Article:

Axle Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$100 to $1,000

Talent:

***

Tools:

22mm, 17mm, 15mm, 13mm socket, 14mm Allen, hammer brass drift, breaker bar, fluid pump, hooked pick

Applicable Models:

Mercedes-Benz W123 (1977-85)

Parts Required:

New axles or CV boots, diff fluid, RTV

Hot Tip:

Keep your spacers

Performance Gain:

Eliminate slop in the drive train

Complementary Modification:

Replace ball joints

Your drive axles or drive shafts can wear out over time or get damaged during use. The most common problem for drive axles is the tearing of the CV boot. This will cause the CV grease to be throw out from the CV joint and allow contaminants in. Lack of grease or contaminants in the CV will quickly lead to failure of the joint. This article will not cover replacing or repacking the CV boot (please see one of our articles on repacking your CV joint and replacing the CV boot) but will cover the removal of the axles. Whether you are working on the boots or replacing the axles, the drive axles will need to come out of the car.

You are going to be draining the differential to remove the axles so make sure to have new fluid, a pump and some good RTV.

Over the years your car may have been serviced by multiple people including previous owners and this can lead to parts replaced with different size fasteners and. 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. If something is different on your vehicle please let us know and share your info to help other users. If you have any questions or comments or even a different procedure you would like to share please leave it below and please leave your vehicle information.

Raise and support rear of vehicle on jack stands. See our tech article on jacking up your W123. If you have any doubts about this job, please do not attempt this project. It should be noted that some of these images come from Peach Parts member dmorrison and it was his first attempt at changing them and he did great.

There are two axles on the W123 and both connect to the wheel hubs through the bearing (red arrows) and the differential.
Figure 1

There are two axles on the W123 and both connect to the wheel hubs through the bearing (red arrows) and the differential.

Begin by first removing the fill plug on the differential (yellow arrow), you always want to remove the fill plug first and it is a lot easier to do it while the rear plate is still securely fastened to the housing.
Figure 2

Begin by first removing the fill plug on the differential (yellow arrow), you always want to remove the fill plug first and it is a lot easier to do it while the rear plate is still securely fastened to the housing. Next remove the drain plug and allow the fluid to completely drain (red arrow).

Depending on the model you have, you will probably need to remove the differential carrier mount or bushing to remove the rear plate (red arrow).
Figure 3

Depending on the model you have, you will probably need to remove the differential carrier mount or bushing to remove the rear plate (red arrow). Place a floor jack under the differential and raise it slightly.

Use a 22mm socket and remove the two bolts holding the bushing to the cover plate (red arrow), the sway may be in the way but it is very thin and will move enough to give you room to get your socket in.
Figure 4

Use a 22mm socket and remove the two bolts holding the bushing to the cover plate (red arrow), the sway may be in the way but it is very thin and will move enough to give you room to get your socket in.

Use a 13mm socket and remove the two bolts holding the bushing to the frame (red arrows) and remove the bushing.
Figure 5

Use a 13mm socket and remove the two bolts holding the bushing to the frame (red arrows) and remove the bushing.

There are a series of 15 and 17mm bolts holding the cover to the housing, use a socket and remove these (red arrow); you may have to lower the differential a small amount to get access to the top bolt.
Figure 6

There are a series of 15 and 17mm bolts holding the cover to the housing, use a socket and remove these (red arrow); you may have to lower the differential a small amount to get access to the top bolt. There is a hole by the drain plug (yellow arrow) that you can insert a punch in and help separate the cover from the housing.

Remove the brake caliper and rotor and hang the caliper out of the way; NEVER let the caliper hang by the brake line.
Figure 7

Remove the brake caliper and rotor and hang the caliper out of the way; NEVER let the caliper hang by the brake line. Please see our article on brake caliper and rotor replacement for additional assistance.

Some people like to break loose the axle shaft bolt using the parking brake as a way to the axle in place but it can put a tremendous stress on the parking brake.
Figure 8

Some people like to break loose the axle shaft bolt using the parking brake as a way to the axle in place but it can put a tremendous stress on the parking brake. I like to insert two of the lugs and use a large screwdriver or bar to brace the hub then use a 13mm socket on a half in ratchet and remove the axle bolt (red arrow). There should be a tube spacer, make sure to keep this for final fitting of the axle. Most of these axle are now made in China and you want to measure the new axle to the old, either way keep this until everything is back together and fits correctly.

You will need to move the axle out of the hub by using a brass drift and hammer, do not use a screwdriver or something that could scratch or mar the inside of the hub.
Figure 9

You will need to move the axle out of the hub by using a brass drift and hammer, do not use a screwdriver or something that could scratch or mar the inside of the hub. You may need to use a large screwdriver on the back side off the bearing to get the axle pried out and away from the hub. Raising the differential will also help give you more clearance.

Hang the axle up out of the way, do not let it drop or hang under its own weight.
Figure 10

Hang the axle up out of the way, do not let it drop or hang under its own weight.

With the differential cover removed use a hooked pick and pull the circlip that helps hold the axle in place.
Figure 11

With the differential cover removed use a hooked pick and pull the circlip that helps hold the axle in place. You may have to spin the axle to get access to the section of the clip you want to pull from. You can now pull the axle out from the differential and remove it from the vehicle. There will be a washer or series of washers on the axle, transfer these to the new axle. These washers are used as spacers to take up any free space between the axle and differential gears. When you install the circlip at the end of the shaft there should be no play. If you are doing both axles make sure to get a couple of baggies and mark and keep both spacers, washers and hardware separate from one side to the other.

Clean off all of the old RTV from both the lid and housing (red arrow).
Figure 12

Clean off all of the old RTV from both the lid and housing (red arrow). Make sure to cover the diff so nothing can get in it which would affect performance later.

Installation is the reverse of removal.
Figure 13

Installation is the reverse of removal. Push the new axle in hard and insert the circlip fully (red arrow), and I can't stress this enough, you do not want the circlip not completely seated and flying off and bouncing around in the diff. Once you have it seated spin the axle to make sure you can see the back side of the clip and that it is in place.

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