Transmission line pressure

Discussion in 'GM Powertrain' started by BluBurb89, Jul 15, 2010.

  1. BluBurb89

    BluBurb89 Rockstar 100 Posts

    Does anyone know how much pressure is built up in the supply and return lines for a TH700r4? I may need to re-route a transmission cooler and need to know what kind of hose to get; really don't want to bend tubing. Will a rubber wire braided line work?
     
  2. jlwz71

    jlwz71 New Member

    11/32 transmission line from your local auto parts store. The most a street 700 will see is about 120#.
     
  3. BluBurb89

    BluBurb89 Rockstar 100 Posts

    Thanks, jlwz71, & tbplus10
    I just ran across this information on this sitewhile trying to google an answer: http://www.hotrodders.com/

    Transmission fluid cooler lines: On the 700R4 the bottom fitting on the right side of the transmission is the "out" line to the cooler and the top fitting is for the return line from the cooler. These fittings are 1/4-inch pipe thread, and CAN include an adapter from the factory for threaded steel lines in an SAE size.

    The transmission fluid pressure readings should be in the ranges of the following numbers (psi):
    Range----Minimum--Maximum
    Park.........90-110...190-230
    Reverse....95-120...200-300
    Neutral.....90-110...190-230
    Overdrive..90-110...190-230
    Drive........90-110...190-230
    Second...185-230...185-230
    Low........185-230...185-230
     
    Last edited: Jul 20, 2010
  4. jlwz71

    jlwz71 New Member

    If you have shift pressures that high (max) better wear a neck brace. That will bark the tires in second on that burb.:gasp:
     
    1 person likes this.
  5. BluBurb89

    BluBurb89 Rockstar 100 Posts

    Wasn't planning to race just doing some cross country towing; I'll leave the "neck brace" driving to more capable hands. As I indicated, I ran across the info on a racer site. I wanted to know what the tranny is and should be doing regarding heat and pressure. Planning to put in a B&M Transpak and was looking for all the info I could get before doing the work. I'd rather build in some safety knowing the operating ranges, than be stuck somewhere because I missed something. I expect to see pressures in the middle; nothing too harsh but not a lot of slippage. Not really into roadside repairs; if I can avoid it initially.
    Thanks for the input.
     
  6. jlwz71

    jlwz71 New Member

    Oh no problem. Just givin ya a hard time.
     
  7. BluBurb89

    BluBurb89 Rockstar 100 Posts

    jlwz71,
    All information and tips are appreciated; I hope you didn't think that I was getting "stiff necked" with you. I know little about transmissions and appreciated what you said about the hard shift, as I may have made a mistake in selecting the correct upgrade kit had your comment not been available to me.
    Thanks again,
    Ted
     

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