Otto Skorzeny wrote:Bruce, what is the reason for so many different gear ratios on the same car? Were there choices when new or did you just get whatever was in there?
The difference between 2.2:1 and 3.15:1 is quite significant.
I recently had a new rear end installed in my truck. The original 2.88:1 gears were no longer made so a 3.0:1 was installed. Just that small change cost me 2 mpg on the highway.
As I said, engines included 5.7 diesel, 5.7, 6.0, 5.0, 4.5, 4.1, 4.1 V6, turbo 3.8, carb
or EFI, used with 4 speed lockup overdrive or 3 speed trans. I don't claim that is even
a complete list for 79-85, and certainly only some were available on a given brand and
year. Don't know if ratio was on the option list at all. I tried a 2.2, 2.41, and 2.73 on
my 79 FWD.
In 77 the General was putting 2.41:1 axles in V8 big cars to get the mileage up. It
worked but launch suffered. After trying some ratios, I concluded a switch pitch
transmission gave me back much of the launch while retaining the economy of a 2.41.
And the switch pitch added a bit of economy as well.
My 79 Eldo has a switch pitch 66 Toro TH425 transmission, with a 2.40:1 overall final
ratio. It also got rid of the failing later final drive. Bruce Roe