diff gears v speedo reading..

[HSV590]

Hi guys, got news the diff bearings are shot in my diff, only makes sense to do the diff gears when getting repaired. The thing is, after I get the diff fixed it will be a couple of weeks until I can get to my tuner to recalibrate the speedo. Are there any guesses as to how far out it might be in the mean time? Putting 3.9's in, runs 20" wheels if that also adds to it...cars a HSV GTO if that helps the guess..
Cheers

[JET-33]

M6 GTO might have had 3.7s stock? so might not be a huge jump

in either case what i would be doing is having the phone or gps unit out for a speedo.

[HSV590]

M6 GTO might have had 3.7s stock? so might not be a huge jump

in either case what i would be doing is having the phone or gps unit out for a speedo.

It's an auto sorry, not quite sure whats standard in the auto HSV's..good tip on the GPS..

Cheers

[JET-33]

which model GTO?

Auto ONLY

VY - 3.07
VY2 - 3.07
VZ - 3.46

are your diff gears still ok? how many km's on them? if its the 3.46s i might be interested :nyuk:

[HSV590]

which model GTO?

Auto ONLY

VY - 3.07
VY2 - 3.07
VZ - 3.46

are your diff gears still ok? how many km's on them? if its the 3.46s i might be interested :nyuk:

It's an early girl, 02 model. done 68000k's Gears are ok as far as I know..

[Stewge]

EDIT: Whoops, stupid delay. Others already got to it.
Also depends on what model/year GTO you have. VY and VZ have different diff ratios as well as the VZ having the T56 M12 which has shorter gears.

[JET-33]

It's an early girl, 02 model. done 68000k's Gears are ok as far as I know..

must be a very early model vy then. damn, ive already got 3.07s. im interested to know how you rate the 3.9s in an auto after its done

[qwigybo]

my mate has 4.11 in his and from memory 140k dash = 100k wheel speed in a vy auto so 3.9 and 20's i'd assume around 130k = 100k 70k = 60k