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Thread: Trans Problems when Towing

  1. #21
    Join Date
    Aug 2012
    Location
    Santa Rosa, CA
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    17

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    Wow. Now I have more to find out. Ineed to call the chevy dealer and ask what and how they did it, what kind of fluid. I'll be a little ticked if they did something wrong.

    I appreciate the input.

    Andy

  2. #22
    Join Date
    Aug 2012
    Location
    Santa Rosa, CA
    Posts
    17

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    Stopped at the dealer today. He told me the trans fluid they use is GM Dextron III. He printed me out a list of the GM recommended fluids.

    He did not appear to know how they performed the flush.

    Andy

  3. #23
    Join Date
    Aug 2012
    Location
    Santa Rosa, CA
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    17

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    Well I think I finally figured this transmission out. There isn't anything wrong with the trans at all. It appears the 2003 duramaxes are rated for 500 ft lbs torque. I re-programed the computer for an additional 80 hp which would be aprox an additional 150 lb torque putting the truck at 650 ftlbs of torque. That's more than the torque converter can handle.

    As I stated before I pull a big heavy trailer. It weighs 13,200 lbs empty. I figure I load an additional 2,000 lbs that puts me at 15,200 lbs.

    I must say with the additional hp and torque the truck sure did perform well. I guess I need to upgrade to a 2007.

    Thanks to all that replied. I appreicate it.

    Andy

  4. #24
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,051

    Arrow

    That explains a lot. For towing that load with a stock 2003 tranny, a maximum of 40-50 HP, and about 120 ft/lb torque is about it before it'll start to slip. If you want more than that, you'll have to upgrade the tranny. A couple tranny builders can upgrade it to handle just about any level of power, limited by your willingness to spend. If you like your truck, want to keep it, and want to run with the extra power, a tranny upgrade may be a better option than a new (new to you) truck.

    80 HP and 150+ torque will do exactly what you're seeing. You need less power, less load, or more powertrain. Simple as that.

    Also keep in mind, extra power often means higher EGT's, which can mean a tranny that survives, but an engine that doesn't. If you don't have gages, with at least a pyrometer, you'll never see the damage coming, and have no way to know when to ease off. These engines are tough, about as tough as any in history, but they have limits. Stay within the limits and they'll live indefinitely. Exceed the limits, and it's only a matter of time before you find the limits.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  5. #25
    Join Date
    Mar 2000
    Location
    Loyal WI US
    Posts
    10,773

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    Quote Originally Posted by Aepozzi View Post
    Well I think I finally figured this transmission out. There isn't anything wrong with the trans at all. It appears the 2003 duramaxes are rated for 500 ft lbs torque. I re-programed the computer for an additional 80 hp which would be aprox an additional 150 lb torque putting the truck at 650 ftlbs of torque. That's more than the torque converter can handle.

    As I stated before I pull a big heavy trailer. It weighs 13,200 lbs empty. I figure I load an additional 2,000 lbs that puts me at 15,200 lbs.

    I must say with the additional hp and torque the truck sure did perform well. I guess I need to upgrade to a 2007.

    Thanks to all that replied. I appreicate it.

    Andy
    The holding capacity of these transmissions can vary from truck to truck. I've got guys towing with my 100HP tune with great success. It's all about how the tune is written and how much "lying" is done in the tuning. The TQ needs to be limited to the 600-650RWTQ range which is well above the numbers being thrown around here. For some reason I don't have the 50HP tune plot posted, but it's very close in fact people often have a hard time knowing which tune they are on by feel unless they floor it. In this case, the TQ is set to be strong and flat without spikes. The lesser tuners tend to dump fuel and create a rush or TQ spike which is what kills the trans.


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