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3.9 or 4.11 gears in an Auto 4spd?

Discussion in 'VY Holden Commodore (2002 - 2004)' started by holdencallous, Jan 15, 2019.

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  1. holdencallous

    holdencallous New Member

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    Hey guys, sorry to make a new thread but I cant find any straight information about the type of gears that would work in an 4spd Auto VY II Calais L37, can anyone give me any information about what gears I should purchase?, I'm trying to get a real pokey launch without sitting at 2300rpm at 100kmh, I've been informed to get either 3.9 or 4.11. I've been told to get 4.11s because a 3.9 won't be enough, but I've also read that 3.9 is enough. I'm at a loss on what to get haha, I'm also not trying to get a totally awful fuel economy.

    Any tips would be greatly appreciated
    Cheers
     
  2. vr304

    vr304 Well-Known Member

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    3.7 would be the max you would wanna go with a 4 speed auto because even that is a massive jump from the stock 3.08, if u go with 3.9s or heaven forbid 4.11 it will be revving it’s guts out at cruising speeds and chewing thru fuel you will just end up hating it.... just for an example my old vr club sport with a 5 speed manual had the same 3.08 gears as standard and I changed it to 3.45 and that was quite a significant difference in pickup etc probably wouldn’t have wanted to go much higher
     
  3. EYY

    EYY Well-Known Member

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    I’ve got 3.9’s and don’t even notice it driving on the freeway. 4.11’s aren’t much different. Revs at around 2300-2400

    They don’t go through any more fuel either. The extra mechanical advantage means that the engine isn’t working as hard, even though it’s revving a little higher (sees less load).

    Traction does become an issue in first and auto shift points will change. I preferred the shift points with 3.07 because it would drop down to 2nd at 100kmph, but now only drops to 3rd. But acceleration is better overall from a standing start.
     
  4. holdencallous

    holdencallous New Member

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    So I dare not get a 3.9 setup?, the bloke that replied earlier says it's fine, I just can't get a straight answer haha.
     
  5. holdencallous

    holdencallous New Member

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    Loss of traction is fun when wanted. Would you recommend a 3.7 setup?
     
  6. vr304

    vr304 Well-Known Member

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    Always the way mate, one mans undriveable is another mans perfect if you get what I’m saying I personally would stick to 3.7 myself but it’s your car at the end of the day
     
  7. gtrboyy

    gtrboyy Well-Known Member

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    Personally prefer 3.9-4.11shorter gears...very little difference in revs

    3.7 for lots of highway driving if people are really worried about it,3.46 if on tight budget from manual car.

    3.0-3.4-3.7-3.9 gears available m80 diffs
    4.11 mainly for smaller m75/m78 diffs

    Shorter diff gears & higher stall convertor/shift kit is what you really want for better launches...tradeoff being use more fuel & quickly get used to it,v6 in heavy car
     
  8. holdencallous

    holdencallous New Member

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    Cheers for the tips mate, How high would my rpm sit on 100kmh with 3.9-4.11?
     
  9. holdencallous

    holdencallous New Member

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    Cheers mate, I'm probably gonna go with a 3.7 setup as if I got a 3.9-4.11 I'd go though fuel much faster than I'd like, and at $1.40 a liter that's not ideal haha
     
  10. EYY

    EYY Well-Known Member

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    You won’t use more fuel. Read my post above.

    You’d be lucky to find a 3.7, 3.9 or 4.11 centre at a good price. If buying new budget $1800-2000.

    Got 2 cars. One 3.08 revs at 1750 at 100kmph. The other has 3.9’s and revs at 2300. Both are silent at 100kmph with no drone but are both v8’s with resonators. I can understand the drone of a 6 becoming annoying with shorter diff gears.
     
  11. holdencallous

    holdencallous New Member

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    Mace sells a diff rebuild gear set for $420, I was thinking of getting a 3.7 and getting the current diff rebuilt professionally but I'm unsure how much a diff specialist would charge me to throw a new set in, so I'll have to see about that.

    Here's the gear set
    https://www.maceengineering.com.au/...HOLDEN-COMMODORE-VS-SERIES-III-VT-VX-VU-VY-VZ
     
  12. immortality

    immortality Administrator Staff Member

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    If you want great acceleration and don't want to compromise fuel economy than a high stall converter that retains the lock up clutch function is what you are after in combination with some diff gears.
     
  13. holdencallous

    holdencallous New Member

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    I've just researched a bit into them, **** oath they seem heaps good for a subtle mod. I'm thinking of a 2500 with 3.7 diff gears?, would you recommend that?
    Cheers
     
  14. immortality

    immortality Administrator Staff Member

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    It'll be a different car.
     
    Last edited: Jan 16, 2019
  15. gtrboyy

    gtrboyy Well-Known Member

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    2800rpm stally with lockup,shift kit & 3.7-3.9 gears...price it all up first then decide.
     

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