Looking to find what options are available for changing the differential on a W123....

What car models have interchangeable final-drive units to that of the W123...? Would those from say, the W124 series fit a W123?

What car models do you know that would fit?

__________________
http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

W123 and pre-'86 W126 chassis. Both the W123 (300D) and W126 (SD) received a 2.88 ratio diff in 1985.

Those are probably hard to find in the UK, which is where the thread starter is.

__________________
'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

I've seen plenty of 2.47 ratio W126 gassers there which will work.

Those are there, but you said 2.88 ratio W123 and W126 diesels.

__________________
'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

I believe the OP is looking for what diff will fit the W123. I don't believe the question was location specific.

The W124 will not fit. Only early, 1st gen, W126 and W123 differentials will mount up.

Thanks Guys!

So, to replace my 3.58 final-drive, in my 280TE/300D conversion the best option is to look for one from a W126 car--Preferably with ABS, (my 280TE has ABS with taco-gen inside final-drive housing....)

Any ideas what model W126 has what ratio, Seems difficult to find any info at all about ratios here.....

__________________
http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

This will help a bit...

ideal highway cruising rpms for a 300d?




.

__________________
1983 123.133 California
- GreaseCar Veg System

Man... this same issue I have been researching about, because I have the same car (1984 e200), and here is some info about the w126 diff:

1st Generation
Years, Model, Engine, Differential Ratio, Differential Case Size
1981-1984, 300 SD, OM617.951 3.0L I5, 3.07, 1.1 Liter
1985, 300 SD, OM617.951 3.0L I5, 2.88, 1.1 Liter
1984-1985, 380 SE, M116.963 3.8L V8, 2.47, 1.3 Liter
1981-1983, 380 SEL, M116.963 3.8L V8, 2.47, 1.3 Liter
1982-1983, 380 SEC, M116.963 3.8L V8, 2.47, 1.3 Liter
1984-1985, 500 SE, M117.963 5.0L V8, 2.47, 1.3 Liter
1984-1985, 500 SEL, M117.963 5.0L V8, 2.47, 1.3 Liter
1984-1985, 500 SEC, M117.963 5.0L V8, 2.24 LSD/2.47, 1.3 Liter

2nd Generation
Years, Model, Engine, Differential Ratio, Differential Case Size
1989-1991, 300 SE, M103.981 3.0L I6, 3.46 1 Liter
1988-1991, 300 SEL, M103.981 3.0L I6, 3.46, 1 Liter
1986-1987, 300 SDL, OM603.961 3.0L I6, 2.88, 1.1 Liter
1991, 350 SD, OM603.97 3.5L I6, 2.82, 1.3 Liter
1990-1991, 350 SDL, OM603.97 3.5L I6, 2.82, 1.3 Liter
1986-1991, 420 SEL, M116.965 4.2L V8, 2.47, 1.3 Liter
1986-1991, 560 SEL, M117.968 5.6L V8, 2.47 ASR/2.47, 1.3 Liter
1986-1991, 560 SEC, M117.968 5.6L V8, 2.47 ASR/2.47 LSD/2.47, 1.3 Liter

I'm targeting a 2.88 or a 2.47.

But note the following; your standard diff may be 3.54 or 3.46, so the lower diff ratio will reduce acceleration from 0, but give better gas mileage and lower rpm on the high way (less headache!), and higher top speed.

Also note, I swapped my 4 gear transmission with a 5 gear w124 transmission, which gave MUCH higher acceleration, but higher rpm on the high way (more headache) and less top speed.

So I hope the w126 diff will fix out the formula, giving moderate acceleration and lower rpm (maybe better gas mileage).

As stated in this blog, the early w126 diff is suitable to fit in our w123 (only needs a solution for the thinner flange), not the w124 diff.

Attached are some charts I hope to be useful in planning our swap (in German, Google translator was a good help).

Regards,
BENZAWY (Oo=l=oO)

Attached Thumbnails

     

Thats interesting, those charts are quite informative...

I know I can get a 2.47 diff from a W126, but think this might be just too low for my N/A 617!
--Guess it would be OK for my long-term project to fit a OM.606, but as it stands, no good I think for a 617....

I havent managed to find any 3.07 or 2.88, as these seem only to be on he American spec cars...

__________________
http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

Try looking for the diff of a w116, it has the same ratio, PLUS it's a seem-less swap....

I couldn't find it here in this part of the world (Egypt)....

I am very excited for this swap, I'm just adjusting financials, and I'll update you as soon as I complete it....

RGDS,
BENZAWY