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Diff gears

Spaced

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Ok people,

I need some advice. I've got a VS V6 auto that I want to change the diff gear ratio. What is the standard? My mate has told me to go for 3.7's. Will 3.7's be too high for a v6 once I get cam, chip exhaust and extractors? What brands should I look at and does anyone know who in Brisbane could do this for me?

Thanks,

:) Spaced :)
 

calais_cruzin

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Hey Spaced,

U doin it all in one hit....

Ino i wouldnt bother with diff gears until i had all the other mods done...

It would probly be one of the last things u would do i u arnt goin to get it done in one hit....
 

Spaced

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Yeah I was thinking to do it last but my mate advised me to do it first so I can get used to it, especially in the wet so I don't get a surprise after the fact. Do you know what the standard ratio is?
 

vq~gangsta

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3.7 is the way2go!

stock ratio is 3.08

3.7 ratios are really good, they're a stronger cog too.

As the VNs have overdrive gears, 3.7 isn't that low a ratio that you're gonna loose heaps of economy on long trips. It may actually increase your economy if you're towing heavy loads (at particular speeds/rpms).

You'll find that it will change your final drive ratio to about halfway between drive and overdrive. So, for example, at 110km/h (with a stock diff) your car does about 3 grand in drive, and 2 grand in overdrive. After you change to a 3.7 diff ratio you'll find it does about 3 1/2 grand in drive, and 2 1/2 grand in overdrive. The difference in fuel economy will be minor. The increase in accelleration will be HUGE.

3.9s and 4.11s are really only for drag cars, the loss in economy just isn't worth it. I personally have a 3.45, which i think is excellent, but you can only get 3.45 ratios second hand from VL turbos (and some NZ commodores I think), and they're no where near as chunky or strong as the 3.7s.

Go for the 3.7 ratio mate, you'll love it!

Oh, and if you're eventually gonna get a chip and dyno tune, make sure the dyno tune is the LAST thing you do (get the diff done first). You want the car to have all the mods done to it before it gets tuned.
 

Spaced

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Ok so it's sorted 3.7's it is. Does anyone know what ball park i'd be looking at to fit this to the vs
 

sting ls2

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Have been thinking on changing the diff ratio on my vz sv6 for a while,just not sure w3hich way to go for 3.46's or 3.7's either way anything would be better than the standard 2.87's.Also can holden fix the speedo after the diff gear change with tech 2.
Any advice would be appreciated.
 

Spaced

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I've been told to go 3.7's by my mate, but my standard ratio is 3.08. 3.46 will give you better launches and quicker 1/4 miles but your revs will be higher on the highway (and you will use more fuel).

Use this calculation
3.73 / 2.87 x revs you sit on at 100km/hr at the moment and you will have what your new revs will be at 100km/hr (this is just a guide).

PM doctor bob he will be able to let you know.

Will probably void your new car warranty as well.

e.g. mine is 3.73 / 3.08 * 2000 = 2422 rpm
 
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