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Dropped rear driveshaft while in motion ... a few questions


NHMJXJ
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I dropped the rear driveshaft pulling into my driveway tonight.  I'm not a mechanic, but I think I can handle this.  I just need some guidance and a few answers.  I swiped the following picture from another site, so you have a visual ... 

 

LOF%20(57).jpg

 

What ever covers the end of the U-joint that fits under the U shaped flat steel plate is GONE (which problably explains the nasty vibration I felt right before the drive shaft dropped). I could back out the bolts that hold that plate on by hand.

 

I literally coasted into the end of my driveway.  I limped the truck into its spot by putting it in part time 4wd, which brings me to question No.1 ... was that a mistake?

 

Second, I foolishly separated the front of driveshaft from the ... transfer case? Yes?  Whatever the doohicky is the front of the driveshaft goes in.  It puked about a cup of fluid.  I did this because I was trying to align the u-joint and couldn't spin the shaft.  I figured if I could just bolt the thing back up, I could yard drive the truck to position it for repair.  Question No. 2 ... does the front of the driveshaft just find a seat?  It didn't spin when I put it back in.

 

Question No. 3 ... I'm guessing I have to have both rear tires off the ground to line up the new u-joint with the rear end.  Yes?

 

help

 

 

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first chock the tires. then put transfer case in neutral. this should make it so you can spin shaft. I am under the assumption that the u joint is still intact ?  if so then yes u can bolt it back up but I would prob replace the u joints since this Is already out. to answer the question it does not hurt the truck to use the part time 4x4 I have made it out of the trail many times like this. as far as the puking of fluid I think it is dex 3  auto transmission fluid just pull the plug on the transfer case and fill it back up after the shaft is in all the way. sorry for the short response but I have to leave the house soon. if anyone wants they can correct me on any of this or give better description thanks.

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What ever covers the end of the U-joint that fits under the U shaped flat steel plate is GONE (which problably explains the nasty vibration I felt right before the drive shaft dropped). I could back out the bolts that hold that plate on by hand.

 

Are you saying that the one of the rear u-joint cups under the steel straps was gone?  :hmm:   If so, the tab on the pinion yoke that holds it in might be snapped off.

 

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Yes, the cup was gone.  The OD of the end of the u-joint would have been swimming under that steel strap, if I'd managed to get everything back up.  I'll look in daylight.  I didn't see any clean, broken metal on anything, but it was dark, I was on my back under the truck with a flashlight in my teeth and my bifocals weren't helping matters.

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Thanks for the tip Jeff ... So vicegrips are definitely out then, right?   (Kidding!) 

 

I called my garage today and they're going to install the U-joints.  Dropping the driveshaft off tomorrow morning

and will pick it up on my way home.  Should be back in action tomorrow night.

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first chock the tires. then put transfer case in neutral. this should make it so you can spin shaft. I am under the assumption that the u joint is still intact ?  if so then yes u can bolt it back up but I would prob replace the u joints since this Is already out. to answer the question it does not hurt the truck to use the part time 4x4 I have made it out of the trail many times like this. as far as the puking of fluid I think it is dex 3  auto transmission fluid just pull the plug on the transfer case and fill it back up after the shaft is in all the way. sorry for the short response but I have to leave the house soon. if anyone wants they can correct me on any of this or give better description thanks.

 

This will work if the central axle disconnect on the front axle is disengaged. Since he pulled into his driveway in 4wd, then presumable shut off the engine without shifting to 2wd first, it is still engaged.

 

So he will either have to start the engine, shift to 2wd and turn it off, or remove the front driveshaft, or lift a front tire off the driveway.

 

Why? Because the NP231J made before 1994 does not have a true neutral. In neutral it locks the front and rear driveshafts together.

 

Shifting the transmission into Neutral and the transfer case into 2wd will always work.

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first chock the tires. then put transfer case in neutral. this should make it so you can spin shaft. I am under the assumption that the u joint is still intact ?  if so then yes u can bolt it back up but I would prob replace the u joints since this Is already out. to answer the question it does not hurt the truck to use the part time 4x4 I have made it out of the trail many times like this. as far as the puking of fluid I think it is dex 3  auto transmission fluid just pull the plug on the transfer case and fill it back up after the shaft is in all the way. sorry for the short response but I have to leave the house soon. if anyone wants they can correct me on any of this or give better description thanks.

 

This will work if the central axle disconnect on the front axle is disengaged. Since he pulled into his driveway in 4wd, then presumable shut off the engine without shifting to 2wd first, it is still engaged.

 

So he will either have to start the engine, shift to 2wd and turn it off, or remove the front driveshaft, or lift a front tire off the driveway.

 

Why? Because the NP231J made before 1994 does not have a true neutral. In neutral it locks the front and rear driveshafts together.

 

Shifting the transmission into Neutral and the transfer case into 2wd will always work.

 

 

x2, I was going to comment the same thing, I didn't know the year they changed it, but I know my tcase locks the front and rear outputs together in neutral.

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There's proof.  This place is full of subject matter experts. I did put the Tcase in neutral and the shaft wouldn't spin. 

 

Only had a little daylight left, so I got both rear wheels off the ground.  With the wheels able to spin freely, I could hand turn the yoke on the rear end to mate with the new u-joint. I slid the driveshaft in, lined up the u-joint and in it went.

 

This must have been a progressive event because my truck never felt smooth, but it rides absolutely vibration free now.  

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