A6 with 3.15 vs 3.55

Discussion in 'Transmission & Drivetrain' started by Mustang1260, May 10, 2018.

  1. Mustang1260

    Mustang1260 Well-Known Member

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    Guys— looking at a new 17 GT with an auto. My 66 Coupe was an auto, my 7 Mustangs thereafter were all sticks.
    Note- this car will Never touch a track. It won't have PP. It will have a real spare tire and cd player. In short an around town car and highway cruiser (not a back road corner carver).

    Ive driven earlier (05,06 autos but i thought those had 2.73 or 3.33. Anyway I hated the auto with the 2.73?? Seemed to bog down about 28-35 mph in and around town traffic while the optional ratio (3.33?) seemed to keep the rpms high enough to aviod this.

    How is the new set up (up to 17my) with the 3.15 or 3.55. Again i dont give a shit about drag racing, just hate being in sitting, creeping traffic and have the damn thing bog or go nuts while going up small hills and constantly hunting and pecking gears.

    Anyone driven both in a 15-17 MY GT.

    I should note I found the perfect option/color car save for it having 3:15s instead of the 3:55s. Short test drives still leaving me with questions.::cheers:

    I will note the car will be involved in several cross country caravans over the next few yrs. Warranty will stay in place thus NO interest in a post sale rear gear change, lund tune etc.
     
  2. Laztug

    Laztug Wanna run dyno slips bro?

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    3.15s and a set of car eyelashes.
     
  3. VooDooDaddy

    VooDooDaddy Well-Known Member

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    These cars (with the 6R80 transmission) perform very well, even with 3.15 gear ratio out back. This is because the first/second gear in the 6R80 are very "short".

    To put it in perspective, even with 3.15's out back combined with first gear in the 6R80 would give you the same effective ratio of a 5.13 rear gear set if you were driving an old GM muscle-car from the late 60's or early 70's with a Turbo 350/400 3-speed automatic transmission.

    5th and 6th gear in the 6R80 are effectively overdrive/super-overdrive.

    I have a 2016 (auto) GT with 3.15 rear gear set, and my car will absolutely haze the 305/35-19 Nittos in 1st and 2nd gear.
     
  4. RIBS

    RIBS Well-Known Member

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    No bog in my 15 GT w 3.15, never unwilling to accelerate strong.
     
  5. gameovergt

    gameovergt Kevin

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    3.55's in my A6 and she screams.
     
  6. Performance nut

    Performance nut Well-Known Member

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    Same and I can do the same with 305/35-19 MPSS unless I get them warmed up really good.

    Personally, I'd hate to run 3.55's on an A6. Effective gear ratios would suck pretty much up to third. First gear would be all but useless. And if you ever installed a power adder... frehgedaboutit
     
  7. lxh89

    lxh89 Well-Known Member

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    I just put 3.55s in my car with a whipple. On the street with drag radials, car does well. It obviously will blow the tires away in 1st/2nd but on a sticky drag strip, I'm hoping to see my 60 drop a tenth. These cars are very heavy so that little bit extra leverage should help it start moving faster.

    Other thing to keep in mind, I'm running 274/40 20 nittos which are 28.7" tall. The effective gearing even with the 3.55s is ~3.37 final gear ratio.

    Tony
     

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