View Single Post
Old 11-20-2013, 02:38 AM
dieseldiehard's Avatar
dieseldiehard dieseldiehard is offline
Join Date: Oct 2002
Location: Bay Area No Calif.
Posts: 4,304
Originally Posted by partsman225 View Post
Has anyone gained fuel mileage from this swap?
I hd a 83 300 D I just rebuilt trans. I do have a 3.87 first gear ratio now .not the old 3.68 so I have better take off now I can fell it. Was thinking of the 2.47 swap. It should take off better with my 91 560 gear set. I get 528 miles per tank w no ac on. W ac between 428 460 per tank
What u swappers think? Thanks

Getting 21-24 mpg on avg ac on. All city.never tried hi way as of yet btw
I owned an '83 300D and after 4 years of driving it I decided to swap an '85 diff into it. The results were amazing. The RPMs dropped about 10% and it actually felt like acceleration was smoother, not from a torque aspect it just got up to speed smoother or something, I recall anticipating a loss of acceleration but it never happened. The car used to have a kick in the pants feeling when it shifted from 1st to 2nd, especially if you let up on the accelerator pedal at the right moment and that seemed to increase with the 2.47 gears like it wanted to get up and go! Under full pedal ie. W.O.T. it really didn't lose any acceleration because the torque curve is flat on the diesel and matched up to the differential perfectly at least with a good running engine.

Around town the mileage was not much different but on trips the car took on a whole new character and improved fuel mileage maybe 25MPG at best, with a heavy foot at times and on the new ULS fuel.
I wished I had done the conversion years earlier. Sold the car to buy a 124 Oh well, I really miss that '83 though. Last of the easy cars to work on and super reliable.
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!
Reply With Quote