• Welcome to SVTPerformance!

4.09 gears?

Discussion in '2015+ Shelby GT350 Mustang' started by 07 Black Beauty, Nov 18, 2018.

  1. 07 Black Beauty

    07 Black Beauty Well-Known Member Established Member

    Messages:
    2,008
    Joined:
    Jan 30, 2011
    Location:
    Florida
    I'm leaning towards swapping to 4.09 gears on my 350 R, and wanted to get some feedback. Is there a noticeable difference? On my 14gt500 going from 3.31 to 3.73 made the car much easier and more enjoyable to drive especially around town.
     
  2. me32

    me32 BEASTLY SHELBY GT500 TVS Premium Member Established Member

    Messages:
    10,693
    Joined:
    Sep 6, 2005
    Location:
    CA,NorCal
    . And yes with the gt350 R the 409 should make the car feel peppier since the power band is all upper RPM
     
    Last edited: Nov 19, 2018
  3. 2000GTSTANG

    2000GTSTANG Well-Known Member Established Member

    Messages:
    1,460
    Joined:
    Nov 26, 2006
    Location:
    Plymouth, MI
    Nope, 4:09's
     
    me32 likes this.
  4. me32

    me32 BEASTLY SHELBY GT500 TVS Premium Member Established Member

    Messages:
    10,693
    Joined:
    Sep 6, 2005
    Location:
    CA,NorCal
    I stand corrected
     
  5. Drewsky65

    Drewsky65 Active Member Established Member

    Messages:
    143
    Joined:
    May 21, 2016
    Location:
    Arizona
    I am curious on this as well !
     
  6. Max97COBRAtkd

    Max97COBRAtkd Well-Known Member Established Member

    Messages:
    1,511
    Joined:
    Oct 24, 2006
    Location:
    Wilmington, NC
    If you plan on staying N/A with it, I would honestly go 4.56 gears. I have 4.09 gears in mine and LOVE them but I will want more in the future for sure. Gears make this car so much more fun to drive over stock.

    Sent from my Pixel 2 using the svtperformance.com mobile app
     
    me32 likes this.
  7. biminiLX

    biminiLX never stock Premium Member Established Member

    Messages:
    8,313
    Joined:
    Jan 17, 2003
    Location:
    Toledo, OH
    Still surprised more haven't done this.
    I've made a decision to get either a GT350 or Backdraft Racing Cobra roadster this spring and any GT350 will get 4.09s immediately.
    If it's anything like my Charger, you can buy a complete center diff with gears and basically bolt into IRS with only 2-4 shop hours tops.
    Why haven't more of you guys gone 4.09s?!
    As above, this car if keeping NA is begging for gears.
    -J
     
    me32 likes this.
  8. GT Premi

    GT Premi Well known member Established Member

    Messages:
    7,961
    Joined:
    Mar 15, 2011
    Location:
    NC
    Probably because people were saying they don't make gears for the GT350. That never did make any sense to me.

    To the people who have done it, is the 4.09 noisier than stock? Also, what brand and where did you purchase?
     
  9. 07 Black Beauty

    07 Black Beauty Well-Known Member Established Member

    Messages:
    2,008
    Joined:
    Jan 30, 2011
    Location:
    Florida

    Ford Racing makes the 4.09, if you go 4.56 Yukon makes them. I've always been told to go with Ford Racing gears which is what I plan to do on the 350 for my first mod.
     
    GT Premi and me32 like this.
  10. ANGREY

    ANGREY Active Member Established Member

    Messages:
    278
    Joined:
    Oct 24, 2017
    I'd love to swap to 4.09's, but I'm terrified of secondary issues (new noises, whines, clunks, etc). Hell, there's even a placebo effect I'm sure where I end up listening closely after a rear end swap and probably hearing things that were always there before but I just didn't focus on previous.

    Perfection would be a steeper rear and a corresponding swap out of 6th to maintain cruising RPM. Most everyone can agree that 6th is useless for anything other than a highway cruising gear, so having livelier 1-5 and a "normal" 6th would be ideal.
     
  11. GT Premi

    GT Premi Well known member Established Member

    Messages:
    7,961
    Joined:
    Mar 15, 2011
    Location:
    NC
    A 4.09 would definitely fix that, but I still wouldn't use 6th for trying to accelerate.
     
  12. 07 Black Beauty

    07 Black Beauty Well-Known Member Established Member

    Messages:
    2,008
    Joined:
    Jan 30, 2011
    Location:
    Florida
    Yeah a noisy rear is definitely a concern. When I swapped to 3.73's on my 14 gt500 it was factory quiet, but I know that's definitely not always the case. I wish I could find a rear with the 4.09's factory installed rather than opening up the rear on mine and hoping for the best
     
  13. ANGREY

    ANGREY Active Member Established Member

    Messages:
    278
    Joined:
    Oct 24, 2017
    Took the plunge and ordered the FRPP 4.09s for the Super 8.8. (M-4209-88409A).

    US Gear makes the same ratio as well as others and offers "stealth" and I'm not sure if the FRPP is 2 angle or 5 angle, but I figured I'd better go with Ford parts if I want a shot at not having additional noise.

    $236 shipped. Once it comes in I'll find a reputable shop to swap them.

    Given that I have only 17k miles, I wouldn't think I need new bearings and I'll ask the shop if they need me to supply the installation kit. Is it foregone conclusion that I need new bolts for the locker?
     
    me32 likes this.
  14. Ablaze

    Ablaze Member Established Member

    Messages:
    315
    Joined:
    May 6, 2012
    Location:
    MD
    Good luck ANGREY! I kept hearing of the GTs outrunning the GT350 and always shook my head at the thought. I look forward to hearing your results.
     
    me32 likes this.
  15. 662

    662 Member Established Member

    Messages:
    108
    Joined:
    Mar 31, 2014
    Location:
    Houston
    I'm very interested in the outcome and if it makes the car better on the track... My buddy drives a modified Viper and he walks from me (albeit slowly) on the straights... I am thinking E85, but sourcing the fuel seems difficult, if the gears can help pull harder it may be worth the budget. Don't need much - famous last words

    Do you know the rpm vs. speed ranges for the 6 transmission gears 4.09 vs. stock and what's stock gear?
     
    Last edited: Dec 7, 2018 at 11:37 PM
  16. biminiLX

    biminiLX never stock Premium Member Established Member

    Messages:
    8,313
    Joined:
    Jan 17, 2003
    Location:
    Toledo, OH
    Stock is 3.73 and the only 2 options are FRPP 4.09 and Yukon 4.56s
    E85 and 4.09s would be a great improvement IMO, good luck.
    -J
     
    me32 likes this.
  17. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

    Messages:
    4,209
    Joined:
    Feb 15, 2008
    Location:
    USA
    I’d go with 4.56, it would be very fun on a high rpm, stickshift car like these. If the stock car came with 4.56’s, it wouldn’t seem out of place imo.

    Here’s a gear calculator to get an idea
    Wallace Racing - Calculate Speed for given RPM, Rear Gear Ratio and Trans Gear Ratio

    The gears are

    1. 3.25
    2. 2.23
    3. 1.61
    4. 1.24
    5. 1.00
    6. .63

    Tires are 28” tall.

    As an example:

    •3.73 (stock) [email protected] is 2000rpm
    •4.09 [email protected] is 2175rpm
    •4.56 [email protected] is 2425rpm

    Another example:

    With 4.56

    [email protected] 46mph
    [email protected] 67mph
    [email protected] 93mph
    [email protected] 120mph
    [email protected] 150mph
    [email protected] 165mph (probably new top speed because less hp at 165mph than the stock gears which would be 5th at almost redline with 3.73’s)

    But short of top speed runs, it’d be very fun
     
  18. ANGREY

    ANGREY Active Member Established Member

    Messages:
    278
    Joined:
    Oct 24, 2017
    US Gear makes a 3.73 a 4.09 and a 4.11 for the super 8.8 IRS. They're coming out with a "stealth" series next year that supposedly is quieter (I'm assuming a 5 angle cut instead of 2 axis like most gears.)
     

Share This Page