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