My 1981 300D rear axle went out. I want to use one off my 1980 parts car. Reading the FSM it seems there was a change in design. I need to read it again but i believe there ar oil passages on the old style 1980 and before ones. I also believe they say replace old style with the new. Does this mean the old style can be used in place of new?

So my question is what are oil passages for and will the 1980 axle work on the '81? Thanks for any help.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

The old style axles have very very fine helical grooves to keep the differential oil where it belongs. The FSM even describes how to re-do those grooves (with sandpaper, as I recall). However, there is a new (later in the 1980s) seal design that eliminates the need for these grooves. I believe that the new seal is the only one sold now so you don't have to worry about the grooves. The lip of the seal (where it contacts the rotating axle shaft) has a series of diagonal lines that protrude a fraction of a mm and act as wipers.

There are two of these seals (one for each axle) that go in the side of the differential. The manuals seem to think that you can remove the old seals with a screwdriver (pry them out) but I found it took something a lot heftier. See this thread for a description and dirty pictures (well, I had oil all over my hands and some got on the camera ).

W123 axle R&R job--some questions?

There are two different kinds of axles, "homokinetic" and "annular." I never did understand the difference. As far as I know, they are interchangeable. Others may have a different opinion to share with us.

You should have no problem swapping the 1980 axle into your 1981 car. Check the rubber boots that cover the constant-velocity joints; if the boots are worn and cracked, they (or the entire assembly) should be replaced. Once the boot cracks open, the fluid inside is lost and the cv joint fails. There are lots of threads on that subject here.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
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Thanks Jeremy. I'll give it a go. wonderful explanation. cheers.

__________________
What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius