au diff ratio

[mr_xr8]

i have an au xr8 and the diff needs a rebuild and want to know if i should change my ratio in it. i have been told it is a 3.2 and should put a 3.9 in it.
i will be getting the car flash tuned by autotech if the ratio gets changed.

[stock au]

I think you will find all xr8 had 3.45 ratio

[Papa Smurf]

I have an XR6 and the ratio is 3.45:1 This is the same as XR8.

I am guessing that this is a Live axle and NOT an IRS setup?

[LG]

All AU XR8s, had 3.45:1 Ratio.

[Papa Smurf]

Originally Posted by LG

All AU XR8s, had 3.45:1 Ratio.

No, I have come across a few 3.23:1 in my time.

[jonbays]

LG's right XR8's have IRS and 3.45 LSD. AU V8's 3.23 and live rear axle.

xr8ute runs 3.9's quite happilly but with a cam so it revs harder to make use of the lower gearing.

[LG]

Thanks jonbays for clearing that up.

[AWD Chaser]

Depends what you want? High speeds for a track? Get a 3.08 (I think, or am I confusing that with an engine CI volume? :P)3.23 or 3.45 are good for normal driving, etc, 3.9 and 4.11 will throw you back in your seat, but when driving at 100kph, expect to go through a bit more fuel, as it revs higher....and with that said, tall diff ratios don't go to well with large exhausts when just cruising down the highway... gives you a headache after a while...

[mr_xr8]

its an IRS. i was talking to richard at craft diff today and said i should go for a 3.73.
i relly dont do any high way driving. i does have a full exhuast 2.5".

[mik]

Originally Posted by mr_xr8

its an IRS. i was talking to richard at craft diff today and said i should go for a 3.73.
i relly dont do any high way driving. i does have a full exhuast 2.5".

sounds like a good thing, did they give you a dollar figure???

[jonbays]

Originally Posted by au3 chaser

Depends what you want? High speeds for a track? Get a 3.08 (I think, or am I confusing that with an engine CI volume? :P)3.23 or 3.45 are good for normal driving, etc, 3.9 and 4.11 will throw you back in your seat, but when driving at 100kph, expect to go through a bit more fuel, as it revs higher....and with that said, tall diff ratios don't go to well with large exhausts when just cruising down the highway... gives you a headache after a while...

well yes thats the idea but the stock AU XR8 with 3.45 will pull almost a true 240kmh anyway so its not in need of higher gearing just more power at higher revs

[jonbays]

Originally Posted by mr_xr8

its an IRS. i was talking to richard at craft diff today and said i should go for a 3.73.
i relly dont do any high way driving. i does have a full exhuast 2.5".

I am thinking the 3.73 to 3.9 is good in the six with a 5750 redline but the 5l V* does like a rev and XR8's should hit the 6250 rev limit so maybe a 3.9 to 4.1 is not too bad if you mod it to rev harder which would be a good idea.

[mr_xr8]

its $1300 but i need a few other little things fixed as well.

it is an auto as well so in terms of revs and shift points spiro said he can set them up at anypoint but i still want it to be safe.