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Chrysler: Transmission grenade theory

  1. #1
    Randy
    Guest

    Transmission grenade theory

    You know the story - just happened to us. Six hours from home, the tranny
    in our 2000 GV self destructed coming off the interstate. Took it to an
    indepenent ATRA shop & opted for a bench rebuild. Failure sequence appears
    to be : Torque converter > pump > everything else. Cost with an 18/18
    nationwide warranty - $2400. Tranny was serviced at severe duty service
    interval. (73,000 on tranny at failure). Our 89 Caravan suffered a similar
    failure at about the same point in its life

    Thinking about this experience led me to this idea which I would like to
    discuss.

    DC uses the same tranny across a broad product line, in vehicles with wide
    ranging GVWR. In the lighter cars with limited seating and hauling
    capabilities, the tranny will hold up for the life of the vehicle. In the
    minivans, the loads are much higher and put more stress on the tranny,
    resulting in a shorter life.

    After two experiences, I think if I purchase another van, I will go full
    size with conventional layout.

    Has anyone done any research on vehicle size/weight vs. tranny failure
    rate?

    Randy

  2. #2
    Ted
    Guest

    Re: Transmission grenade theory


    "Randy Bishop" <net> wrote in message
    news:PfAhb.901$starband.net... 
    appears 
    similar 

    I don't think that you could, for two reasons:

    1) The 41TE/A604 has gone through so many revisions that you can't get an
    apples-to-apples comparison.

    2) By the time you hit 70K+ miles, how the car was being driven is more of
    an impact.

    Consider this. The stress presented to the tranny is a ratio of
    accelleration to inertia. In
    short, a 2000pound vehicle accellerated at, say 1m/sec presents the same
    stress on the
    tranny as a 1000pound vehicle accellerated at, say 2m/sec

    Now, granted if you feather-foot a heavy vehicle in order to keep the strain
    down
    to the same level as normal driving a light vehicle, the upshot is that the
    strain placed
    on the tranny for the heavier vehicle simply lasts longer in order to get
    both vehicles
    up to the same speed. So another way of saying it is that you can choose to
    have
    a lot of strain on the tranny for a short period, or a little strain on the
    tranny for a
    longer period, irregardless of vehicle weight, just by adjusting your
    driving, but in
    the last analysis, the tranny that is hauling the heavier vehicle does more
    work.

    BUT, the crucial thing that I have observed about mechanical systems, is
    that WEAR
    seems to be directly related to the strain placed on the device. In short,
    a tranny that is under high
    strain for a short period of time wears a lot faster than a tranny that is
    placed under
    low strain for longer periods, even if both trannies do the same work.

    So to put it in laymans terms and relate it to your problem, the A604/41TE
    may be
    perfectly adequate tranny for even heavier vehicles, depending on who is
    driving and
    how they are driving. So I don't think that a study is going to show any
    difference unless
    it takes into account the driving style of how the vehicle is driven.

    And one last thing to throw on the fire - heat TREMENDOUSLY accelerates
    wear. I suspect that a huge number of early transmission failures could
    have been
    avoided simply by the factory plumbing in a decent transmission cooler
    instead of
    circulating it through a heat exchanger in the radiator. While you need
    some heat in the
    trans fluid for correct viscosity, it would be interesting to see the long
    term results
    of a trans where the fluid was maintained at 90 degrees instead of 120-150.

    Ted



  3. #3
    Bill
    Guest

    Re: Transmission grenade theory



    Ted Mittelstaedt wrote: 

    You meant to say the *product* of acceleration and inertia - work the
    numbers (ratio vs. product) in your example that follows and you'll se
    what I mean. Obviously as either acceleration *or* inertia go up, so
    does stress on the tranny.
     

    Bill Putney
    (to reply by e-mail, replace the last letter of the alphabet in my
    address with "x")


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  4. #4
    Brayton
    Guest

    Re: Transmission grenade theory

    Would the size of the transmission cooler be dependent on the climate
    that the car is used in? For example, where I live, the absolute 'blow-your
    mind' high temperature would be 80°F, and in the worst of the winter, it
    could get down to -40°F at the worst. Wouldn't the factory cooling solution
    be sufficient in the winter time here, yet a factory option overkill at the
    same time? (Winter lasts about 4 to 5 months here.) I would suspect that
    in some cars, it's possible to be too cool. Yes no?




    "Bill Putney" <net> wrote in message
    news:net... 
    the same stress on the 



  5. #5
    Ted
    Guest

    Re: Transmission grenade theory


    "Bill Putney" <net> wrote in message
    news:net... 

    Your exactly right, I muffed that one. I also muffed another one when I
    said that wear was proportional to stress, it's not, it's a logrithmic
    function. In short, as stress increases at a steady rate, my experience
    is that wear increases at a much more rapid rate.


    Ted



  6. #6
    Ted
    Guest

    Re: Transmission grenade theory


    "Brayton" <com> wrote in message
    news:.. 
    'blow-your 
    solution 
    the 

    Yes. In fact, many semitrucks have zippered covers over the grill of the
    truck, you will see in wet and cold weather many of them will zip them up
    to cover half the radiator, else the cooling from the radiator is too great.

    With autos, you do avoid some of that because most cars now have
    thermostatically controlled electric cooling fans, and of course the engine
    thermostat in the radiator will shut the coolant flow down if the coolant
    gets
    too cold. It wouldn't take much to rig an electronic (or mechanical) bypass
    valve on the tranny hydraulic lines to perform a similar function.

    Ted



  7. #7
    Ivo
    Guest

    Re: Transmission grenade theory

    "Ted Mittelstaedt" <placo.com> wrote in
    news:newscache$tdhomh$wzg1$ipinc.net:
     

    Ted,
    Then it's quite the opposite of logarithmic, namely it is exponential.

    Cheers,
    IK

  8. #8
    Randy
    Guest

    Re: Transmission grenade theory



    Perhaps in relation to the style of driving, the terrain the vehicle runs
    in has an effect on tranny longevity. Here in Upstate New York Finger
    lakes region we have a combination of steep hills and high speeds which
    would also dovetail with the excessive heat shortening tranny life points
    you made. I think the aux cooling idea is sound and I will put in a cooler
    with this rebuild.

    Any recommendations for a cooler in a high stress application for these
    trannys?

    Randy


 

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