Guys,
I recently picked up a mint condition 1980 w116 300SD California model. I am trying to figure out what rear differential gear came in the California model because I can do 80mpg at 2400rpm. Yes 2400! I know my federal 49 state version 1980 300SD is closer to 3600 rpm at 80mph. So what's going on here? What was the special rear gear ration on the California 1980 model? I mean I can literally do 100mph at 3400rpm. I have never experienced this on a diesel before. It seems to be a one year only rear end for the California model 1980 300SD.
Thank you
Maybe a diff swap during the car's lifetime?
There was no special rear axle ratio for California 300SD models. Both federal and California models were all 3.07:1. Either someone has swapped out the rear axle as Daniel suggested, or the tach or speedometer are off because they're from a different car, and will not read correctly.
I would love to know what rear axle they swapped in! My only complaint about the SD is she's noisy on the highway! And getting some better MPG would be great as well.
measure it.?...why speculate.?!
Wow, that's a big delta. That rear end would have a ratio in the low 2.x range. I would imagine your acceleration is, shall we say, rather uninspiring?