6.4 Hemi Gear Swap

Discussion in 'Heavy Duty' started by mtofell, Dec 9, 2015.

  1. Phil21502

    Phil21502 Senior Member

    Age:
    32
    Posts:
    121
    Likes Received:
    30
    Joined:
    May 9, 2017
    Location:
    Frostburg, MD
    Ram Year:
    2015
    Engine:
    6.4
    No towing yet and as far as hills go it actually goes up hills now with out wanting to downshift all the time. When getting on it good it just flat out runs. Idk how else to explain it. Lol. I know the evic mileage doesn't really count but I was getting 12.5 before and it's staying right around 14 now. I never expected that. Keep in mind I have 35's and a hemifever tune with mds turned off.
     
    ramessesII likes this.
  2. Ratket

    Ratket Senior Member

    Posts:
    2,309
    Likes Received:
    545
    Joined:
    Jul 14, 2014
    Location:
    Arizona-
    Ram Year:
    2014 2500
    Engine:
    Hemi 6.4
    If u turn on mds I bet u would get awesome mileage on long trips-
     
    SETEX 6.4 likes this.
  3. kry226

    kry226 Member

    Posts:
    66
    Likes Received:
    23
    Joined:
    Dec 19, 2014
    Location:
    Germany
    Ram Year:
    2004
    Engine:
    5.9 Cummins
    Alright, thanks. Keep us posted on future experiences.
     
  4. LDBagger17

    LDBagger17 Member

    Posts:
    67
    Likes Received:
    29
    Joined:
    Aug 11, 2015
    Location:
    Central Pa.
    Ram Year:
    2015
    Engine:
    Hemi 6.4
    Hopefully rear diff gets new gears today-tomorrow, got a friend who is off and going to help do swap
     
    14RAM4X4 likes this.
  5. LDBagger17

    LDBagger17 Member

    Posts:
    67
    Likes Received:
    29
    Joined:
    Aug 11, 2015
    Location:
    Central Pa.
    Ram Year:
    2015
    Engine:
    Hemi 6.4
    So got rear diff gear swap done, will do front asap. Installed genuine AAM 4.44 gear set, no pinion depth markings anywhere, was told by someone at AAM to use original pinion shim. Installed original shim as a base line and had horrible pattern, put together checked pattern and tore back down and changed shim 4 times. Finally wound up with an great pattern on drive side, coast side is a little toward toe side of gear but has full contact, did final assembly and filled with oil. Drove several short drives 6,13 and 30 miles with breaks in between and check for leaks and recheck oil level yesterday. Today drove 26 miles then almost 100 miles, can tell a real difference in the truck and mpg's are definently better .5-1 mpg. Absolutely no gear noise, mds is a lot more active, and holds in higher gear much better, had to accelerate pretty quick once and could tell a big difference. I will know a lot more after towing later this week, need to break in a little more first. All in all very happy with job and gear choice, also installed AAM finned aluminum cover, case temp this afternoon after driving almost 100 miles, was 126 ambient was 82.
     
  6. 15BlueStreak

    15BlueStreak Senior Member

    Posts:
    183
    Likes Received:
    66
    Joined:
    Sep 25, 2015
    Location:
    Green Springs, OH
    Ram Year:
    2015
    Engine:
    Hemi 6.4
    Bagger what were your original gears. And what is your tire size? I am really looking into doing 4.56 gears from the 4.10s that I have now. Its a big gamble. But I really think it will put my truck in its sweet spot for towing. Even though rpm difference is not all that much between the two its not all about rpms as more of the mechanical advantage the gears would give.
     
  7. LDBagger17

    LDBagger17 Member

    Posts:
    67
    Likes Received:
    29
    Joined:
    Aug 11, 2015
    Location:
    Central Pa.
    Ram Year:
    2015
    Engine:
    Hemi 6.4
    was 4.10 and stock tires 235 80 17 I'll post an update end of week will be towing 36' travel trailer 110 miles north through mountains to Williamsport Pa. I went with oem gear sets and they were cheaper than good aftermarket gear sets
     
  8. Ratket

    Ratket Senior Member

    Posts:
    2,309
    Likes Received:
    545
    Joined:
    Jul 14, 2014
    Location:
    Arizona-
    Ram Year:
    2014 2500
    Engine:
    Hemi 6.4
    Ram really neeeds to toss out anything under 4:10 and offer up to 4:88"s. 373 gears are only a viable option under perfect conditions that are rarely replicated " For a gas motor"I bet your mds will activate a lot more and stay active even more yielding better fuel mileage. Plus now when towing I bet you could prolly hold 3rd gear instead of 2nd on the steepest of grades. 3:73"s are fine for a diesel motor that produces all of its tq/hp under 3k Rpms which is how our trannies are designed. I envy you!!
     
  9. LDBagger17

    LDBagger17 Member

    Posts:
    67
    Likes Received:
    29
    Joined:
    Aug 11, 2015
    Location:
    Central Pa.
    Ram Year:
    2015
    Engine:
    Hemi 6.4
    I have to agree never drove or towed with a 6.4 3.73 combination, but judging from the difference I notice already going from 4.10 to 4.44, I can image 3.73 gears would be a real disappointment. Don't envy me though your wise for gathering info.
     
  10. RainDesert

    RainDesert Member

    Posts:
    58
    Likes Received:
    10
    Joined:
    Mar 13, 2017
    Location:
    OR
    Ram Year:
    2017
    Engine:
    6.2
    Thanks for the report LDBagger. I couldn't agree more that Ram should be offering at least their already available 4.44 to the entire 6.4 lineup.
     

Share This Page