W126 Differential Ratios

The W126 range was in production from 1979-1991.  I’ve never seen a comprehensive table of W126 differential ratios, so I have attempted to create my own.   Not only did they vary between models and years, but in some cases countries too.

It is possible I have missed a few more country specific ratios.   Please indicate in the comments below if I have.

If this table is being referred to for swaps, the first and second generations diffs are not interchangeable.   Neither is an ASR diff.   LSD was standard on 560s but optional on other cars.    The exception is cars equipped with ASR that have a different differential.

In addition, the 8 cylinder cars used a larger case (1.3l) than the smaller engined cars.

My personal view is that with first gear start, the standard ratio could be made taller.   This would improve acceleration and make the mostly useless first gear usable.   This is certainly the case on my 300SE.   I would have preferred the ratio provided for France, but with first gear start.

It is also interesting to see the 560 used a shorter ratio than the 500 or the 420.   It seems clear Mercedes saw it as more of a hot rod whereas the 500 was the autobahn cruiser with its tall 2.24 diff ratio.   In selecting the W126 differential ratios, I’m also not sure why Mercedes Benz went to the effort of producing 2.82 and 2.88 gear sets when they are so close together.

Mercedes-Benz went on a fuel efficiency drive during 1981 which is why the V8 cars got revised ratios.   The project was called the “Energy Program” and included other changes such as the revised Bore/Stroke of the 380 engine.

ModelRatio
First Generation
280S
280SE
280SEL
3.46
380SE (1980-1981)
380SE (AUS)
380SEL (AUS)
380SEC (AUS)
3.27
300SD (1981-1984)3.07
300SD (1985)2.88
500SE (1980-1981)2.82
380SE (1982-1985)
500SEL (USA)
2.47
500SE (1982-1985)2.24
Second Generation
260SE
300SE
300SEL
3.46
300SE (FR)
300SEL (FR)
3.07
350SD
350SDL
2.82
300SDL2.88
560SE
560SEL
560SEC
2.65
420SE
420SEL
420SEC
560SEL (USA / AUS)
560SEC (USA / AUS)
2.47
500SE
500SEL
500SEC
2.24

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