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  • th400 seal(?) question

    I've got a 79 CJ7 with the TH400/quadratrac combo, and I'm trying to figure out if I have trans fluid leakage problems. Any one with the same setup who has had theirs apart would be extremely helpful!!!!!!

    I replaced my stock quadratrac with an identical t-case that has a milemarker part-time conversion kit in it. According to milemarker, the correct fluid after changing to this kit is ATF. After driving the jeep with the new setup, I had a leak from between the t-case and the adapter that bolts it to the tranny. I took the t-case off, assuming the leak was from worn front seals on the t-case input bore. But fluid began to drip from the bearing (in the adapter housing) on the tranny output shaft. Now I have unbolted the adapter from the tranny and let all the fluid that was in there drain. Should there be fluid this far back in the tranny? If so, how much? I probably drained a full quart-1.5 quarts including the stuff that leaked all over the garage floor. It's the section of the trans that houses the governor. I don't really want to do a complete rebuild of my tranny if I don't have to.

    thanks,
    MattJ

  • #2
    after more thinking, I'm guessing with the governor assembly and bearing back there, there should be fluid flow to lubricate these things. I've read elsewhere that the th400 doesn't have a rear seal, that there are 2 seals in the t-case instead. one keeps trans fluid out, one keeps case fluid in.

    still hoping for input from somebody,
    MattJ

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    • #3
      Matt. I just finished a complete rebuild of the TH400/Quadratrac combo. You are correct. There are two seals on the input shaft side. You can see them in this picture (http://www.t-r-j.com/Auto/QT/quadratrac.htm). You are also correct that there needs to be fluid in the back of the mission. 4WD sells the complete seal kit for the Quadratrac for $19.99. That's what I used. Make sure you use extra RTV between the TH400 case and the trans case. The small paper gasket that goes in between isn't enough if there is any imperfections in the mating surfaces. Good luck!

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      • #4
        You ROCK!!!!!!!!!!!!!!!!!!!! I got the seal kit, just working on swapping the milemarker stuff into my old case, because I found out the new case I got has some damage - the sun gear for the low range unit is grinding on the back half of the case. Also, my leak may have been so bad because there was only one seal in the t-case! Whoever installed this low range unit really f-ed up because there's RTV all through the case. I think they weren't very familiar with the quadratrac and sorta slapped the lowrange on there when my father-in-law bought the jeep because it was a deal breaker - he had to tow it behind the motorhome and needed neutral. Thanks for the RTV/gasket tip - when I did the install the first time I only put enough in the corners to hold it in place. I didn't really want to be scraping the tranny adapter if I ever had to take it apart. At least the leak alerted me to some other problems I didn't know I had.

        Thanks a ton for your reply - I'm a lot more confident now. I should be back on the road saturday!

        MattJ

        Comment


        • #5
          mdunn - did you find an easy way to pull the snap rings that hold in the rear output shaft bearing? I guess it's called the "annular bearing". I'm fighting with it right now.

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          • #6
            Matt. If I remember correctly, these are the one without the snap ring plier holes right? I took a very small, hardened screw driver and carefully got behind the snap ring at the gap (do not damage the case by prying on it). Once you push it in a little I took another screwdriver and walked the snap ring around and out. Hope this helps. Nothing is never "easy". Good luck.

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            • #7
              Yeah, that's what I did. I finally got the case with the part-time kit fully disassembled. Now, I get to do it all over again with my case and install this kit. I should be an expert soon. Thanks for all your help.

              MattJ

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