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  1. #1
    David Guest

    Default allison 5 speed automatic transmission has problems

    i have a 2001 chevrolet truck and just returned from my first trip towing my fifth wheel. much to my surprise chevrolet left out the gear selector for 4th gear, wich makes for poor towing. i have 1 2 3 D there is no 4.this is the only transmission that i know of that does not have a selector for each gear in the transmission. i wish i had my old truck back.
    Last edited by Mark Sedenquist; 07-08-2006 at 09:46 PM.

  2. #2
    Join Date
    Jan 1998
    Las Vegas, Nevada

    Default A source of considerable angst!

    That is the first I have heard of that problem. I can see how that would really drive you crazy! What size 5th wheel were you towing? Types of conditions? How about over-heating issues? Anything else you can share about this engine?


  3. #3
    David Guest

    Default Can't Find the Correct Gear!

    I am towing a 28 ft carrie lite fifth wheel. so far my temp gage has
    only got up to 200 degrees on the transmission. i just sold a 98
    chevrolet 2500 with a 454 engine and i wish i had it back, it done a
    better job of towing this same fifth wheel than the new one. both trucks
    had 373 rear end. allison has admitted they made a mistake but place the
    blame on chevrolet truck division. the reason they left the selector off
    is they did not have selector quadrants for a 5 speed and used the old
    ones and had to leave one out, and then made the big mistake of leaving
    out 4th. when towing with the new truck it is hunting all the time back
    and forth between 5th and 4th, 5th gear is to high an 4th is just right
    but there is no way to keep from shifting into 5th. i am making the same
    trip i always make from battle creek to brimley, its all expressway and
    the hills are not bad, and the air is cooler up north and makes for
    cooler towing. what can they leave out next with out telling us? the
    computer for the transmission can be reprogramed and they can change
    3ard selector and make it 4th instead, but they have not written the
    program yet. am waiting to see if it is possible to get it fixed. the
    people at allison have been super but no one from chevrolet will speak
    with me, i have talked with a gm man twice. thank you for your e-mail i
    hope this helps some one. dave

  4. #4
    David Guest

    Default More Gearing Information

    Here is some additional info:
    The 98 truck with 373 rear end turned 3000 rpms at 70 miles per hour in 3ard gear and 2000 rpms in 4th gear.
    The 2001 truck turns 3000 rpms at 70 in 4th gear,except you can not keep it from shifting into 5th. and it turns 2000 rpms at 70 miles in 5th gear.

    So the only gear ratio change in the transmission is in the 1 2 3 gear 4
    and 5 are the same as the old 3and 4. both trucks had 373 rear end. i
    would have thought they should have distributed the extra gear a little
    more equally throughout all the speeds. thanks again dave

  5. #5
    pauls Guest

    Default Remedy

    I seen you had a problem where you wanted to hold in 4th gear and not let it go to 5th.. I found a resolution to it... please visit

    This shows you how to hook up a switch that allows the transmission not to shift into 5th until you turn it off.. I have used this and it works great. It is involved. The transmission is equipped with the lockout from 5 the gear but GM never used it.. Allison has gave the information out.


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