W123 Rear Axle
 

Hello. I'm following this article to replace the rear axle on a 1983 300D: PeachPartsWiki: Replacing the Rear Axles. Try as I might, I cannot get the new axle installed. I've loosed the shock, removed the brake caliper, and have jacked up the differential to various heights. I cannot get the wheelside splines inserted. And I would say by a 1/4". Any suggestions appreciated. Thanks, Carolyn.

Well Carolyn, they don't just "fall" into place. First, are you sure you have the right part. I would say on the axle, that since so many models use the same part, it would be difficult to have the wrong one. I have had some small difficulty in getting the spline into the wheel also, with with some shaking, perhaps some light tapping with a hammer, it should go all the way. I am assuming that by saying except for 1/4 inch you mean it is all the way but for that short distance. Take a break, rest up a little, and try it again. If it is like the old one, it will go in.

Do you mean you cannot start them? Or get them finished?

If its that you cannot finish them, you can use the axle bolt to help pull them in.

Also, you mention that you have jacked the differential up to various heights. That really can't be done, though it can be dropped somewhat. The differential is bolted to the bottom of the car floor or pan. If it is unbolted you can drop it various distances and that does make installation easier "sometimes" That spline is machined so as to be very close to the matching spline and if there is no oil on it, it can slide pretty hard. If you can back it out a bit, I would suggest a light film of oil on it might help a lot, maybe even a spray of WD-40.

I wish I could be concerned about splines matching up - I'm just trying to get the end of axle over the wheel hub.

Have you bought the correct axle? The W126 axle shaft is longer than the W123 one but it looks the same.

The Axles can telescope inwares on themselves to some degree making them shorter
In order to move the differential up and down you need to support it with a Jack and I think you need to remvove the Differential Mount completely. That is the part the very rear of the Differential that attaches to the Body and to the Differantial.

I can remember on Mine I had stick a Pry Bar in between the Hub and carefully pry to get it in. However, I have Mercedes Axles.

Are you installing Original Mercedes Axle?

Hmm... So you are having problems getting the outside end to clear the spindle and go in. For that, you need the car supported and BOTH wheels off the ground dangling, then the diff jacked as high as it will go. It should then slip right in. The emergency cable does get in the way. Got a pic?

I just did this job on my 240D last fall. I did the same as vstech explained then monkeyed with the outside joint a bit I found I had to get it at just the proper angle and it barely cleared and slipped in. I had the half-shaft below it's home and the joint pointed as far up as it would go.

I replaced the part that attaches the diff to the body while I had it off.

I found the most difficult part of this job was getting the spring clips back inside the diff, around the end of the shaft with needle-nose pliers. I had saved the washers that were between the diff and the old half-shafts, put them on the new parts, and just couldn't get the clips back on.

Consequently they were off by the same thickness as those washers so I took them back out and everything slid into place the second time perfectly.

I had a small drip from my rear diff before this work and found the PO had used form-a-gasket or similar material. So I cleaned all the surfaces carefully and put it back together carefully and eliminated the leak.

it you are having huge trouble, x2 this. compare your new axle to the one pulled out. the 126 axle is identical looking but slightly longer. i have had one incorrectly shipped to me by a parts warehouse in a 123 part number box. they get mixed up all the time by parts suppliers

After ensuring that you do indeed have the correct axle, which BTW doesn't sound like the problem if it is only 1/4", try lowering the axle completely and inserting the hub end before raising the differential. I had trouble with this as well and I had to use this method.