diff ratio

[CAM05L]

hi guys goin to do the ratio change on my calais cause the limo has loosend up so while i pull it out i myt aswell change it. wat would be best 3.45 or 3.7? i do a little bit of freeway drivin but i am not really fussed about fuel economy and so on, its more for just performance. anyone have quarter mile times after a change? i have run 15.0 in full standard trim so if it would go a bit better i would be happy. cheers

[1991_Vn2nV]

3.7's would be the best choice man out of those 2, personally im going with 3.89's.

[CAM05L]

yeh i think ill go the 3.7. not sure about 3.89 though can the trans be able to be re-calibrated if you went for such a ratio?

[1991_Vn2nV]

Re-calibrated for what exactly?

[immortality]

go for the 3.7 if economy is not an issue. nothing to re calibrate. fit the gears and go. or maybe shift kit the box for better shifts etc and a good trans cooler wouldn't hurt either

[CAM05L]

was unda the impression that the gearbox needs to have the shift points re-calibrated??? not sure im not a trans specialist.

[Boonz]

nah the shift points are controlled by the kickdown cable and the pressure the trans fluid is under, the trans sorts itself out one thing you will ahve to do tho is get your speedo calibrated.
ive got 3.45's with my auto box and 100 k's shows 125 on the speedo, i checked it with GPS just to make sure

[Full Spectrum]

Hey i dont want too hijack this thread but i thought it's better then starting a new one.
With changing diff gears.
What are they above the stock 3.08. And what type of performance gain do you get,
How much more fuel used?
How many more RPM @ 100-110 etc?
I'm thinking of the 3.7 was at first thinking 3.89.
I don't hit the free ways very much at all, But when i do i want too be able too travel nice, In December i'm going too shepparton and my car now sits on 1700-1800 rpm at 100 it's fantastic on fuel on freeways. How much will it put me out.
And also where about do you have it recalibrated?? I'm going for a rebuild LSD do they do it?.