HELP; can't get driveshaft in

Verse

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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?
 
("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
 
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.
 
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.
 
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?
 
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
 
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?

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
 
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.
 
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.
 
Maybe nobody is watching this old thread, but here is my recent experience. I had my 66 Fury on stands with all 4 wheels hanging free. The driveshaft would not slide forward enough to allow the rear u-joint to slip out of the diff yoke. I discovered that lifting the differential a few inches solved the problem. Looking at the geometry, I concluded that the downward "swing" of the rear axle/spring on the front spring mount also forced the axle to move forward and push the transmission slip yoke almost to it's limit. Hope this helps someone. Lindsay
 
Maybe nobody is watching this old thread, but here is my recent experience. I had my 66 Fury on stands with all 4 wheels hanging free. The driveshaft would not slide forward enough to allow the rear u-joint to slip out of the diff yoke. I discovered that lifting the differential a few inches solved the problem. Looking at the geometry, I concluded that the downward "swing" of the rear axle/spring on the front spring mount also forced the axle to move forward and push the transmission slip yoke almost to it's limit. Hope this helps someone. Lindsay

Yep! MUCH of the work under these cars presupposes having the suspension "under load" so to speak. While I've had the wheels all off the ground, this invariably happened with jack stands on the rear axle, thus preserving the state of loading the rear springs. The sole exception to this state being when replacing the rear springs themselves, I would rest a big 4x4 under the rear frame rails, then put cinder blocks under that, after using jack stands.

Glad to know you beat this bind. Rolllll that Mopar now!
 
Yep! MUCH of the work under these cars presupposes having the suspension "under load" so to speak. While I've had the wheels all off the ground, this invariably happened with jack stands on the rear axle, thus preserving the state of loading the rear springs. The sole exception to this state being when replacing the rear springs themselves, I would rest a big 4x4 under the rear frame rails, then put cinder blocks under that, after using jack stands.

Glad to know you beat this bind. Rolllll that Mopar now!
The Fury is rolling! ready for the Atlantic nationals this week. Best week in my year!!
Always be careful if using cinder blocks under a car. IMHO they are a hazzard since they are prone to fracture and collapse. They are often placed on thier side (openings horizontal) and then have less strength. also if loaded under stress (not on flat surface) they can crack. The "old guy" sometimes feels obligated to offer warnings. I would feel some responsibility if I did not and later found out someone was injured. Lindsay
 
The Fury is rolling! ready for the Atlantic nationals this week. Best week in my year!!
Always be careful if using cinder blocks under a car. IMHO they are a hazzard since they are prone to fracture and collapse. They are often placed on thier side (openings horizontal) and then have less strength. also if loaded under stress (not on flat surface) they can crack. The "old guy" sometimes feels obligated to offer warnings. I would feel some responsibility if I did not and later found out someone was injured. Lindsay

Warnings already well known w.r.t. cinder blocks. Thge best way to use them is to lay them horizontally, with all pressure distributed over all the sides, and a board on top, acting to distribute the weight evenly. To wit, laid as they would be in a building. Solid Acme bricks are FAR better, but now too expensive if obtainable from old construction. RR ties work, when inured contra bugs.

Glad to know the Fury rolls!
 
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