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Changing Diff Ratio in FG-X Ute


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  • Member For: 1m 10d

I am looking to change the diff ratio on my Auto, Naturally Aspirated FG-X Cab Chassis Ute. Currently it has a 2.73:1 Ratio. I am going to put in a limited slip diff as the car has no traction stock, and am planning to change up the ratio while I'm at it. I would like better off the line acceleration, without having an excessively loud and high revving engine during daily driving.

 

This car has new headers, cams and an air intake in it's near future.

 

What ratio would you choose and what performance gains can I expect?

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  • Member For: 1y 11m 20d
  • Gender: Male
  • Location: Perth

3.7.1 is a good solid diff ration for v8's. Ultimately your car will rev more, and burning more fuel is 100% assured. It will definatley give you a bigger/better launch off the line by a huge margin. Though personally, I have a 4.11 ratio in my old XF with a 5 speed ........and she completely jumps of the line , if I let it. Personally, I have played with 3 diff ratio's over 3 different falcons.......and it was all for that extra jump off the line. I had a 3 speed  behind my 351 with a ration of 3.7.5.......and she was 4000rpm at 85kPH. I wouldnt push it up to 100kpm often. But u have a 6 speed in the FGX, this will definitely not be a problem for you, though regardless.....you will burn more fuel and the motor will rev more. I haven't seen much info of people playing with the diff rations in FG's and was shocked when I found it to be a 2.73. sh*t...the mighty XF came out with 2.77 or 2.92. But I would expect the ratio was wound back with the FG to give it a bit better fuel economy and help with traction. I guarantee you, whatever ratio you pick, you wont be happy with.......you'll want the next one up, after you get your car back. But If your going to play with the ratio.......don't go to a messily 3.08.......Go upto a bare minimum of 3.27 and have a feel of it. 

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  • Member For: 1m 10d

Hey mate, it's the NA Inline 6. I've went from the 2.73 to the 3.45 and I am having it installed on Monday. They used the 3.45 in the manuals and from what I hear, it's easy to adjust for in a tune. Having my tuner adjust my speedo for the new gear ratio early August. Wish me luck mate!

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  • Farken yeah nah
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  • Member For: 7y 6m 13d
  • Location: South Australia

I've driven an FG turbo with 4.11? diff gears and despite having only 300kw the farken thing moved! I can't remember the exact rpm it sat on for 100kph but it wasn't too much.

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  • Farken yeah nah
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  • Member For: 7y 6m 13d
  • Location: South Australia

I'd say it'll make a much bigger difference in an NA car than a turbo car. Reason being is that you can change turbo size and boost pressure to give a better low down experience. With an NA car you're limited by power for the most part so you need something to make it jump off the line and reach the powerband earlier.

 

I think a 3k converter with lockup would work just as good as a diff ratio change in an NA car, they both have their pros and cons. I can't tell you if it would knock off 2 seconds from your 0-100 time, 2 seconds is a lot but it will help it leave the line much better and give it more in gear acceleration.

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