ZF 8-Speed is Best Auto Trans.

Discussion in 'Challenger DIY/Tech Info' started by SRT-Tom, May 31, 2022.

Car Parts
  1. SRT-Tom

    SRT-Tom Well-Known Member Super Moderator Article Writer

    Posts:
    5,744
    Likes Received:
    1,552
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey
  2. stingray

    stingray Full Access Member

    Posts:
    571
    Likes Received:
    95
    Joined:
    Feb 26, 2012
    Location:
    California
    But is this the current 8 Spd. auto trans in the current 2022/2023 Challenger R/T SPWB? It is made in GERMANY? What about the MDS problem? Is it as simple as switching it to SPORT MODE not "ECHO" mode to avoid running on 4 cylinders so you don't wear out engine faster?:eek::facepalm::snoopfacepalm:
     
  3. SRT-Tom

    SRT-Tom Well-Known Member Super Moderator Article Writer

    Posts:
    5,744
    Likes Received:
    1,552
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey

    The issues with MDS cylinder deactivation have no bearing on the quality and performance of the automatic transmission.
     
  4. stingray

    stingray Full Access Member

    Posts:
    571
    Likes Received:
    95
    Joined:
    Feb 26, 2012
    Location:
    California
    Then why is it that it is the MDS that is equipped on the 8 spd. automatic having problems? :think:
    The manual transmission doesn't have this problem because it does not have MDS feature. You just have to pay gas guzzler tax.:Pshyco:
     
  5. SRT-Tom

    SRT-Tom Well-Known Member Super Moderator Article Writer

    Posts:
    5,744
    Likes Received:
    1,552
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey

    The 8-speed automatic has nothing to do with MDS issues. It's all about the cylinder deactivation, and its effect on the engine, that is necessary to meet CAFE mileage standards.

    The manual transmission doesn't have MDS because it doesn't need it to meet the mileage standards. It's all about final drive ratios.
    The automatic has a higher overall ratio than the 6-speed. The MDS takes time to transition in and out of 4-cylinder mode and the automatic transmission has the ability to buffer the engine with the torque converter if you stomp the throttle while it's transitioning back to 8-cylinder operation. Without the torque converter, there would be more noise, vibration and harshness.

    As stated above, a manual's 6th gear is such a deep overdrive gear that MDS is not needed. If you drive a 5.7 manual, you will notice, when you are in 6th gear on the highway, it has nothing left when you stomp on it. The rpm on the tach when you hit 75 mph is about 1,700-1,800 rpm. Honda, for example, only uses MDS in its automatic models where the torque converter, filled with fluid, dampens the engine vibration. Since the manual gearing is a direct connection, the 3-cylinder mode is disabled.

    Also, another reason manuals don't have MDS is because the entire system requires the ability to monitor actual torque output vs. demand. With an automatic, the PCM knows what gear it is in and can compare MAP signal, throttle position, gear position and vehicle speed. Once a certain threshold is crossed, MDS kicks in. However, with a manual, the PCM has no idea what gear its in, and therefore is unable to determine how much torque the vehicle needs to maintain a certain speed. This is the main factor that the PCM uses to decide whether to activate MDS or not. The stick hits the same MPG without MDS that the auto does with MDS. Here are the EPA fuel mileage estimates for a 5.7 and a 6.4 engine:

    5.7 Auto. (with MDS)- 19.25 mpg.
    5.7 Manual- 18/23 mpg.
    6.4 Auto. (with MDS)- 18/24 mpg.
    6.4 manual- 17/23 mpg.

    I would also guess that it is probably more technically difficult to add MDS to a manual car where the driver has more input to the transmission system, versus one where the driver is not involved as much (i.e., automatic). Also, 6-speed drivers are a minority. They bought this type of Challenger because it's more of a "drivers car." Anyone willing to sacrifice a little performance for a better driving experience will not buy a car with MDS. They also more likely bought it as a "toy" and don't care about gas mileage.
     
  6. stingray

    stingray Full Access Member

    Posts:
    571
    Likes Received:
    95
    Joined:
    Feb 26, 2012
    Location:
    California
    So if you have MDS just put it in "sport mode" with the 8 spd. automatic and no worries.
     
    NC20RT likes this.
  7. TRCM

    TRCM Full Access Member

    Posts:
    1,146
    Likes Received:
    446
    Joined:
    Dec 21, 2019
    Location:
    Southeast VA

    Depends on year...mine still does MDS even in sport mode....
     
  8. stingray

    stingray Full Access Member

    Posts:
    571
    Likes Received:
    95
    Joined:
    Feb 26, 2012
    Location:
    California
    2022
     
  9. TRCM

    TRCM Full Access Member

    Posts:
    1,146
    Likes Received:
    446
    Joined:
    Dec 21, 2019
    Location:
    Southeast VA
    not all years kill MDS is what I was saying.....
     
  10. stingray

    stingray Full Access Member

    Posts:
    571
    Likes Received:
    95
    Joined:
    Feb 26, 2012
    Location:
    California
    I don't understand what you mean by that. You mean not all years have problems with MDS? I just heard that Dodge never addressed this problem and it's current from the old to the new cars of 2022.