diferential ratio

[sevensixty]

i have one(3) qestion(s): is the automatic transmition diferential ratio the same on the diesel transmision and petrol(gas) transmition? for 740 volvo .

my friend has diferential from diesel...and i am not sure if the ratio is the same from gas(petrol) car ok?


i have manual trans but want to put in diferential from automatic...so are they the same from diesel and gas????

thanks for answers

[Jason]

I'm not sure on the ratio that would come with a gas car with auto trans, but the diesel 7 series with ZF22 auto had a 3.73 ratio, the M46 equiped cars had a 3.54. The 3.73s will be nice for drag racing with the shorter gearing, however you are going to pick up some RPMs in OD and fuel economy is going to suffer somewhat.

Jason

[piper109]

From my information, the 740 with ZF and D24T has a 3.93 ratio. The turbo gas cars of a similar period had 3.73.
I concur on the 3.54 for the M46 equipped cars but I have never seen anything that would suggest that the ZF came with anything other than the 3.93. I suppose there may be a difference wagon from sedan but my 85 donor sedan (now scrapped) had 3.93 as does my 85 wagon.
The overdrive on the ZF tranny is much taller than the manual w/add-on overdrive and the overall ratio for both vehicles is about the same when in overdrive. They will run about 3150 to 3200rpm in top gear at 80 mph.
I retro fitted a 1992 gas car with 3.73 locker and fitted ZF and D24T. The overall ratio is taller than the std car of 1985 and 1986 but it seems to be able to cope OK.
This means that if you fit a rear axle from an auto equipped diesel, you will run higher rpm on the highway and accelerate slightly quicker too.
My 85 wagon which I retro fitted from ZF to M46 runs about 3700 rpm at 80 mph but its quick when nipping around.

cheers, Steve

[VolvoBro]

Ratio seems about right.