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352's avatar
352
Explorer II
May 19, 2013

A question about transmissions

I have a 2000 Dodge with a 47re tranny. I had a 96 Ford 7.3 auto tranny that I could down shift going down the mountains to maintain a slow speed. I have done a little research and found the 47re does not lock up the TC by down shifting and it does not slow you down. I also understand that you can buy an inexpensive kit with a jumper and a switch to lock and unlock the TC. My question is if I just use the lock up on the TC going down hill will I damage the tranny? Thanks
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8 Replies

  • 352's avatar
    352
    Explorer II
    May 20, 2013
    My conversation with a Chrysler transmission tech was that if you put your foot on the accelerator just a tad going down hill the TC will stay locked in overdrive and 3rd. 1st and second not. No need for an extra brake now. Thanks to all.
  • restlesswind's avatar
    restlesswind
    Explorer
    May 19, 2013
    ScottG wrote:
    Another vote for the Pac Brake. You'll kick yourself for not getting one earlier.

    Ditto and Ditto
    One of the best investments I have made!
  • ScottG's avatar
    ScottG
    Nomad
    May 19, 2013
    Another vote for the Pac Brake. You'll kick yourself for not getting one earlier.
  • carringb's avatar
    carringb
    Explorer
    May 19, 2013
    As hinted above.... It's really the motor not provide braking, and has little to do with the transmission. Even if you added a bypass switch to manually lock the TC, you still won't have any engine braking (My '03 work truck was an F650 5.9CTD/6-speed man). You really need the exhaust brake.
  • 45Ricochet's avatar
    45Ricochet
    Explorer
    May 19, 2013
    ScottG wrote:
    When Dodge added exhaust brakes to the Cummins, they found that a thrust washer in the trans would suffer from compression braking. So it was replaced with a different design (in 06).
    The odd thing is lots of guys had been using EB's and had not reported any problems with "thrust washers".
    If it were me, I would get one of the controllers you spoke of and enjoy the benefits. You may also find and EB would be nice.
    Just keep in mind that it's possible you may have trans damage eventually.


    X2 for the most part

    No doubt a Cummins going downhill is like a anchor in water, zero braking.
    I would skip the Jacobs and look at the Pac Brake setup with your 47.
    The 47's were the weak link that every OB guys talk about, and remind us about.
    But like Scott said, I'd use one but be ready for the damage down the road at some point.
    Good Luck
  • ScottG's avatar
    ScottG
    Nomad
    May 19, 2013
    When Dodge added exhaust brakes to the Cummins, they found that a thrust washer in the trans would suffer from compression braking. So it was replaced with a different design (in 06).
    The odd thing is lots of guys had been using EB's and had not reported any problems with "thrust washers".
    If it were me, I would get one of the controllers you spoke of and enjoy the benefits. You may also find and EB would be nice.
    Just keep in mind that it's possible you may have trans damage eventually.

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