Quote:
Originally Posted by blankenship
found it.
so, the 'donor' diff says 3.46 and the 'current' diff that's on my '85 wagon says 3.07.
i don't believe i have the shims for the donor...as he just gave the the differential itself, nothing mounted to the car.
does it sound like a bad idea swap anyway, for a 70% highway driver?
also, how do you know when an axle shaft's bad?
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That isn't the swap you want to do for better highway RPMs and mpg.
If you HAD the 3.46 installed and were talking about swapping IN the 3.07 then you'd be going in the right direction...
With a 3.07 in there if you want to get even lower highway RPMs and mileage, you have to go to the 2.88 ratio - from the 85 300 series IIRC, or one of the 2.47 ratio rear ends from a gasser.
You can get the same effect as the 2.88 ratio by increasing your tire size by about 6%-7%. For example going from 195/70/14 tires to 225/75/14 tires is about a 6.5% increase in diameter.
You can't get the same effect as going from 3.07 to 2.47 with bigger tires though. That is a nearly 25% increase and you can't go to tires THAT much bigger - that would take a 315/80/14 - basically a truck tire that wouldn't even come close to fitting.
Now, if you want to make it a smokin' 0-60 machine, go ahead and swap in that 3.46 diff...
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1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock
1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown