Standard BA XR6T diff ratio for 6 speed man?

[ken666]

What is the standard diff ratio for a 2005 BA mk2 XR6T with a 6 speed manual?

I'm swapping it out with an earlier XR8 3.46:1 unit, due to a hat failure temporarily until I have finished building a twin bush cradle and locker diff combo.

Only problem is, the info sticker on the current diff has been painted over!

I read a few conflicting forums on the web, some claiming all 6 speed BA manuals are 3.7:1 and other saying 3.46:1?

I'm certain my XR8 6 speed was 3.46 originally.

I don't want to go any taller than whatever is in it now, as I spend 4-5 hours a week in peak hour Sydney traffic...... at least 2 of those are in 1st gear and slipping the extremely heavy twin ceramic clutch!!

[k31th]

all 6 speed manual XR6T/F6 variants have a 3.73:1 ratio diff.

[ken666]

I would assume that the other 6 speed variants that are fitted with the 3.46 ratio, must be geared lower.

What is the configuration, ie.. 5 speed with one overdrive, or 4 speed with 2 overdrives like the commodore?

My XR8 is much quicker off the line into the powerband in 1st and 2nd, but seems to have a wider ratio set than my turbo does.

And the rpm at 100km/h is a couple hundred lower.

Although this could be because of the wheel diameter difference, 18" Vs 20"s?

[arronm]

XR8 had 3.46. Keith is right XR6 F6 had 3.73

Edited 02/01/19 11:59 AM by arronm

[ken666]

Well, that has helped me decide what ratio gears to fit in the new diff I will start building in my spare time....

4.11:1 it will be.

I can still remember how difficult my XB GT coupe used to be at low speeds, because of the gearing and big cam etc, first gear was 2.32:1!! and final drive was 3:1.

It used to pull 120 in first!

Ford have always geared too tall in the lower gears for my liking, that's why commodores felt so much snappier off the line.

[k31th]

yep; too bad the late model camira's are the slowest thing once you get to 30km/h... having the ford gearing means you get plenty of first gear to easily spin the wheels at 30km/h+ and 2nd makes it over 100km/h for slightly faster 0-100 times haha

[ken666]

But as you know only too well, your 60ft times can be the difference of winning to losing. its not easy to play "catch up" if both cars are similar in power.

too much noise pedal, and not getting the launch right...... you lose, too little and you bog down, as you watch the better geared car drive away.

I still haven't found the best way to launch my rocket! I have just settled for the gentle low rpm method then nail it while still suffering turbo lag, relying on my top end power to make up for such a slow start!!

I probably should have got one with the ZF auto.

[k31th]

yeah, the auto's are a very good match up to the turbocharged 4L torque monster that is our engines; as compared to the manual's which are a challenge to launch such a heavy vehicle quickly and then smoothly transition and maintain boost as you go through the gears...