lower geared rear end question
 

Greetings!

I have a 1982 euro 300d 5speed. the final drive ratio in the diff I believe is a 3.56. I want to get lower rpms while on the highway. the engine seems to be a bit strung while doing much over 75mph. I am considering replacing the 3.56 with a 3.07 differential from a later domestic model. The one thing im worried about is premature clutch wear while starting from a stop with lower ratios. Does anyone have any knowledge on this idea? thanks alot!

Greg

The auto trans W123 300D 1980-81 used a 3.46/1
The 300Dt's from 1982 use the 3.07/1 & that would be a good ratio for your car.

the higher
 

gear will make taking off a little more hard on the clutch if you are an aggressive launcher. if you take it easy taking off you should be fine., unless you live in san francisco.

tom w

thanks for the responces! this is a 82 300D 5spd manual trans with a non turbo motor(euro model). i have yet to look at the stamp on the diff. to determine the ratio. if it is a 3.46 i'll install a 3.07. and if its a 3.07 maybe get one from an 85 300dt. didn't they switch rear ends for the 85 models?

Funny you should mention San Fransisco. my father, whose car it is, is actually moving back to tha bay area in a few months and wanted lower RPM's while on the HWY cross country. Funny!

Greg

Yes, the US 82-84 300D turbos have a 3.07. The 85 has a higher ratio (lower number), but I don't remember the ratio. I don't know if I would go any higher than 3.07 with a NA engine. A 3.07 results in about 3500 rpm at 80 mph with my auto tranny.