Originally Posted by RAVEN
2500rpm-2600rpm With 3.7 Gears, I ALSO HEARD THAT 2.77GEARS ARE A OPEN WHEELER NOT LSD,3.08 , 3.23 and 3.43 had lsd but not 2.77.
noooooo not THAT high!
EB, are you sure your car has a 2.77? It should surely have a 3.08 or 3.23/3.27 diff in it. 2.77s were last seen in 3 speed EAs. Your RPMs at 100kph sound about right for a 2.77, which suggests this ratio has been retrofitted at some point in time.
2.77s were either open wheeler OR LSD. I think pretty much all the diff ratios could be optioned as LSD or not.
3.73 should give 2281rpm at 110kph for you.
Equation = 1700 (at 110) / 2.77 = 613.7184 (dividing rpms by old diff ratio)
(multiplying this by new diff ratio) 613.7184 * 3.73 = 2281rpm
Keep in mind you might not be able to fit 3.73 gears into a 2.77 diff's housing. Do some research before committing to gears.
Also, you'll need to correct your speedo. DO NOT replace the calibration gear, as this will stuff up your auto's shift points, etc. There's a circuit available thru Jaycar that fixes the speedo error without stuffing up your auto's behaviour, but I don't have the link on me at the moment sorry.
So a search in the archives of the www. fordforums .com .au forum, there should be some info there.