R/C107 Differential Ratios

The R/C107 models had an extremely long production run – 18 years.   There were a variety of different models and specification changes.   This included the differential ratios that can have a big impact on the performance and economy of the vehicle.

In compiling the table below, I have tried to research the various country specific variants.   It is possible I have missed a few.  Please indicate in the comments below if that is the case.

The SL and SLC of the year had the same mechanical specification (at least during the SLCs production run).   The only exception was the 450SLC 5.0 where there was no equivalent 450SL 5.0 until the facelift and the 500SL model.   

Many of the same aspects that were covered in the W126 table are applicable here.   As with the W126, the V8 models received the larger (1.3l) case.    Also, as with the W126 models, 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.

Early in the first generation production, the 450 models moved from a 3.07 ratio to 3.06.   This was achieved by changing from a 46:15 gear set to a 52:17 gear set.   This was more of a minor specification change than any real impact on the car.

From the long term ownership of a 450SLC, I think the chosen ratio works well for that car.   I’m not as sure of some of the other ratios.   My view is that some of the later ratios were too tall.   They probably worked a bit better for the home market on the Autobahn than in countries with lower speed limits.

The other factor to take into account is that this generation of Mercedes-Benz automatic transmission did not feature a lock-up torque converter.   This means there will be some level of slip and engine revs will be slightly higher than the theoretical number.