300SD 1983 Axle Flange Kit and easy axle changes - PeachParts Mercedes-Benz Forum

rhodes2010 · #1 07-07-2013, 12:17 PM

At the junkyard yesterday and found several W126 MB from 1981 to 1989.
Some had annular axles, some had homokinetic, some had the outer weight ring that unbolts from around the can.

Then there was this one that was labeled 1981, it was a 2 door 5 liter engine.
Badge gone off the trunk, but must be a 5xx SEC .
Inside drivers door tags says manufactured 1981, imported 1983.

This model had axles the same length as my homokinetic axle, but
with annular inner joints, and flanges with built in weight rings.

I have read that the larger weight ring is an obstruction in the 300SD diesel
because of the fuel line, and I believe it. My fuel line is extremely close to the can on the inner right axle.

So after removing these axles from the 1981 I left them in the trunk.

Doing this gave me a chance to measure the length of the spline and smooth shaft on the flange side. (1 1/4 inch smooth shaft, 1 inch spline).

I realize that converting to flanges on the small differential 1983 300SD
will require getting those original axles out to study the inside axle stub.

I really want flange / annular style axles in the car and if I have to change to the larger 210mm rear end I will do that.

There are a lot of posts on this board about people trying to get different gear ratios, and several comments that getting those gasoline car gear ratios
has not improved diesel gas mileage, so that is not my motivation.

I thought that getting a pre 1986 W126 set of axles was all that was needed
but now I see those weights, and different differential size and it gets confusing.

Can anyone offer a simple answer on getting from where I am.
A stock 1983 300SD with what appears to be a 7 inch wide differential (185mm) with homokinetic axles, the differential has the mount dead center
(as opposed to the side mounted diff cap that appears on 1986 and above W126) .

To: Annular axles.
If I get any W126 with center mount diff can I slip in that with its attached axles ? (even if it is the 8 inch / 210mm )

Some of the posts talk about the pinion/driveshaft (propeller) mount being different.

In the end I may end up simply sending out these axles , getting them rebuilt, and be done with it.

Any advice is appreciated.