82 300d axle replacement
 

Was underneath checking a leaking brake line, and noticed that my right rear axle boot was torn. I can move the axle left and right about an inch. I checked to make sure that the bolt through the hub was tight, and it was. So what am I looking at here? I assume that the axle needs to be replaced, but what else will I need once I start digging in there?

It's normal for there to be in and out play in the axle CV joints. They are designed to move in and out as the car moves. What you do not want is play when rotating the axles back and forth, nor should there be noise from the axles.

But it's true that if the boot is torn, and it's been torn for an unknown period of time, it is likely best to consider replacing it.

I've had good luck with re-manufactured Genuine axles from CVJ axles. Google them. You will need to return your axle as a core to get $75/axle back. Quality is good, though, and the price for each axle is not much more at all then the aftermarket knock-offs.

The job is generally straight forward. You will need to re-fill the differential with fluid as replacing the axles involves draining it and removing the rear cover.

You will also want to consider replacing the seals on the side of the differential. Even if they look good when you remove the axle, there are reports that they will begin to leak shortly after installing the new axle. Corteco OEM quality seals are inexpensive, so it's good insurance to replace them.

Otherwise, the only real consideration relates to ensuring that upon installation there is no play of the axle end that enters the differential. There are shims that will be re-used; if the axles don't fit snugly when the c-clips are installed then a different size shim will be required. vstech has recently mentioned he has lots of shims available, so you can contact him before you go to the dealer for parts.

Here is a DIY guide:

PeachPartsWiki: Replacing the Rear Axles

Thanks for the info, that's exactly what I wanted to know. One other thing: When I push the axle back and forth, the bolt on the outside of the hub moves in and out. Is this normal, or is there other damage besides the axle?

if the outer bolt moves, it is not tight.

Any tighter and it's going to be broken. The boot appears to be moving away from the diff, is there anything that could have loosened up on that end?

There's really not much else going on back there. The rear ends on these cars are fairly simple.

The axle is held in on the wheel side by that bolt, and on the differential side by a c-clip. That's it.

I think at this point, since it needs to be replaced anyway, your best bet is to simply pull out that axle. Give everything a looking over and if you're still concerned about other issues, you can report back with anything you may find.

I'd remove the bolt and examine it. it may be damaged...

or you may have the wrong axle in the car.
someone may have put a w123 axle in a w126

since you have a 123, it's unlikely to be the wrong axle, but it's POSSIBLE, your bolt on the end is missing the torque tube.

the bolt is supposed to be passing through a large washer, and a tube that covers around 80% of it's length.

Bolt looks immaculate, the spacer and washer are in place, and the bolt is tight to the spacer. The majority of the movement is on the diff side. Is it possible that I threw the c clip out of the diff? I'm going to take a long this afternoon, not sure if I will pull the diff cover tonight or not

There was a recent case of just that, someone found their c-clip had come off. Probably due to the wrong size shim being installed, but not sure on that.

If the BOLT is moving, it's NOT THE DIFF causing the movement.

I have not had My Axles off for a long time but what I remember is there is a tubular Spacer, a Washer and the Bolt.
I believe the washer is made in a manner that puts tension on the Bolt. If the Washer is collasped the The Axle is going to be loose even if the Bolt is tight.
There is 2 different sizes of those Bolts so you need to be careful what you order.

With the Axle going in and out of the Hub you are going to wear the splines in the Hub and a new Hub is like $350 each and too much work to remove at a Junk Yard. Better to get the whole Trailing Arm.

The Washer is listed as a Clamping Disc and is supposed to be a one time use. If I remember correctly the washer is cupped/dished so that acts like a spring washer.
It could be that someone assemble yours with the cupped/dished part facing the wrong way or it is just flat and needs replacing.

I don't know the Deatails on the Bolt sizes.

On the Differential Side there May be a Spacer/Shim/Washer that adjusts the Fit of the C Clip.
When the C clip is installe and the fit is propper the Axle should have no in and out play.

If you exchange your Axles or replace with a New Axle be sure to keep the Spacer/Shim/Washer as they are matched to the Differential.

There is different thicknesses of Spacer/Shim/Washers that you can buy.

One of our Members was selling good re-booted Axles.

You could remove the Axle with the Cracked Boot and remove the old Boot and clean it out good and pack that Can completly with CV Joint Grease and install another Boot and hope that noting inside was damaged to cause the Joint to Fail.

If the end of your CV Axle at the Differential has Bolts going through it you can re-boot it with a Stock Boot because it can come apart from that end.

The Axles that have Cans on each end can be rebooted by stretching Dorman Unifit or Astoria Flex Boots over the Cans.

At Autozone a single Dorman Unifit Boot Kit is about $17, other Autopart Stores sell them. The Grease Packet that comes with the Boot is not enough so you will need to buy more CV Joint Grease.

Forum Members prefer the Astora Flexx Boots.

I re-booted both of My Axles with the Dorman Unifit Boots using a Plastic Cone Tool instead of the ATF Funnel.

If you decide to go with Made in ????? Axles I would get them locally and be sure to save the Receipt so you can bring them back if there is any fitment issues or you need the warranty.

If you order online calify with the Seller who is going to pay for the Shipping of the warranty Axle back to them and to ship the replacement Axle to you before you purchase any from them. I would do that by way of Email so that you have a Copy of what was said.

For what it's worth, I can report that CVJ requires the owner to 1) pay return shipping on cores and 2) pay return shipping on warranty returns.

Shipping for 2 axles for me via FedEx ground was $25.