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Help with 4l60e in Tahoe

Discussion in '1992-Present Chevy & GMC models' started by cpqtim, Feb 11, 2002.

  1. cpqtim

    cpqtim Registered Member

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    Location:
    Westport Ky.
    Guys,
    I have a 96 Tahoe (also 73 Blazer) and I am having a tranny problem. At this point I hear a whining noise that is timed to engine RPM. It is more pronounced while in gear. Almost sounds like a noise you would hear in an AM radio from ignition noise but I know it is not that. The sound seems to be coming from the tranny and I think it may be a pump or something like that. The truck has 96K on it with about 20K of those towing a 5600lb boat on the highway. I have serviced the tranny every 10 to 15K.

    Will a 4L60e whine when it is going bad? GM rated the towing capacity on this Tahoe at about 5 or 6K. I am considering getting a 4L80e from the junkyard and having it rebuilt. Is this a straight swap over or am I getting into a project with no end in sight?

    Is there any kit than actually beef up the 4L60e to handle the weight I am towing? I plan on someday needing to tow 9000 lbs. When that day came I thought about pulling the engine and putting in a 400 small block and a 400 tranny. What may be involved in doing this conversion? I know I would lose the OD and have some computer bypassing to do but has anyone done this?

    Any thoughts?
    Tim T.
     
  2. lt1yj

    lt1yj 1/2 ton status

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    Near Chicago, IL
    I can't answer your questions about the transmission problem.

    I can answer the interchangeability between the 4L60E and the 4L80E. It can be done but it's really not worth the effort for a tow vehicle.

    Basically, the computer controls are completely different between the 4L60E and the 4L80E. The wiring harnesses are not compatible. You can get a stand alone computer and harness for the 4L80E but then you would have to have your current computer reprogrammed to remove the transmission controls. You might be able to find the complete setup from a truck with the 4L80E in it and swap it over. Possible but a lot of work.

    Physically the 4L80E is longer than the 4L60E by ~2-3". The output shaft is 32 spline versus 27 for the 4L60E. So you'd need to swap out the input shaft on the Tcase and get the driveshafts modified.
     
  3. Pookster

    Pookster 1/2 ton status

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    the 4l60E Is not a bad tranny, but from what I hear, it is pretty heat sensitive. If I were you, I'd get an extra large cooler in the mean time. Check also the U-joints., make sure its not a driveline vibe..
     
  4. eman

    eman Registered Member

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    Not a bad tranny compared to what? It is a rolling defect in my opinion. GM made several major changes in late 99 because of several decades of failures by using a car tranny in trucks.
     

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