HELP; can't get driveshaft in

Engine, Transmission & Driveline

  1. Verse

    Verse Member

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    On my 66 Newport, I have installed a newly rebuilt 745 transmission. I cleaned and lubed the yoke splines with some grease. I am meeting a lot of resistance trying to get the yoke to slide over the splines. The splines are engaged. I bumped up against what I think is the rear oil seal, and had to gently persuade it past that with a block and hammer. So far nothing is binding though; I can still slide the yoke back again by hand. I am still not in far enough, and the yoke does not want to go further. I am afraid to get too aggressive.
    Any ideas what is going on?
     
  2. CBODY67

    CBODY67 Old Man with a Hat

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    ("745 transmission"?)

    In general, you should see the wear marks on the yoke where the orig seal AND tailshaft bushing wore against it. Use those for guides on the situation as "far enough in". Each wear area should have "a range" rather than a single pattern, for each. But there should be a more-pronounced pattern for "ride height" normal placement.

    Possibly holding the yoke up to the side of the housing to visualize where things are? If not already doing it, might be easier to use the yoke without the driveshaft attached?

    If all else fails, contact the trans rebuilder for assistance.

    Keep us posted,
    CBODY67
     
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  3. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    Take a picture of how far the yoke is pushing in if you can't get it, but my suggestion for the moment is to give the shaft a partial turn and try it.

    You might have a nick or burr on the spline (most likely) , but sometimes it's all about how it wore over the years. Might take a few tries to catch the right mating splines, but it's worth a try before you have to pull it apart.
     
  4. traintech55

    traintech55 Senior Member

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    How much grease did you put in the yoke. If the vent on the back of the yoke is clogged, the grease will compact and not let you insert it far enough to install the rear U joint.
     
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  5. bluefury361

    bluefury361 Old Man with a Hat

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    NEVER use a hammer to force a slip yoke !!!!!!!! Is the drive shaft not going in far enough to engage the rear u-joint? Is it the same drive shaft that came out of the car? Same transmission?
     
  6. '66 Fury I

    '66 Fury I Member

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    The 754 in my 66 Fury had a seal on the output shaft forward of the spline. This sealed to the inside bore of the yoke in front of the spline. The rear of the slip yoke was completely open. It seems this was a one year only design. Could be a problem with that "extra" seal?? Just a thought. Check your FSM. Lindsay
     
  7. 69 300 vert

    69 300 vert Well-Known Member

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    Rebuilt huh? Look at the rear trans seal, does it have the OEM extended boot? Or is it flush with the rear of the trans like nearly all the aftermarket seals? If it is flush, are you trying to push the yoke in to the wear mark on the yoke from the OEM extended boot?

    s-l1600.jpg
     
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  8. Gerald Morris

    Gerald Morris Senior Member

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    Pull the yoke back out, and MEASURE the depth of your splines, inside the yoke. Then, measure the total depth of the yoke. Using the first measurement, mark with a Sharpie the end of the splined area on the outside of your yoke. This should be the absolute maximum depth to which the splined output shaft inside the extension can go to in your yoke.

    Now, measure the distance from the end of the output shaft to the outer edge of the seal. Take the difference between this and the depth of your yoke's splined area. See if your yoke will slide in so far as to leave no more yoke showing than this difference. If so, you've slid it home.

    If you can't slide the yoke home, try turning it a few degrees, then mating the splines in again. After so many decades, these things wear in a bit, and some positions will slide home more easily than others. I had to replace my U joints a couple months ago, so this little exercise remains fresh in memory. I used some red moly grease, (NLGI Grade 2, as specified) but want to replace the red moly with Lubriplate's NLGI 2 bearing grease, which Mopar preferred when these cars were made. I'll get my chance to re-lube the yoke when I replace my rear leaf springs this Spring. If the yoke won't slide forward and out easily after a few tries, then scream at the shop that rebuilt your tranny.

    After you get the yoke to go forward into the extension, see if your rear U joint will now allow you to replace the propeller shaft. It should. NOW, slide the shaft back toward the rear end until the rear U joint is nested well into the seats of your pinion yoke. If you've made it this far, all is well, tighten your nuts on the U bolts in the pinion, tidy up, then take your ride for a test drive.
     
  9. PH27L7

    PH27L7 Active Member

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    Since you say this is a newly rebuilt unit I strongly suspect the tailshaft bushing was improperly installed. Unfortunately the transmission tail housing must be removed to correct this.