BENT MAIN DRIVE SHAFT; OK TO RUN IN FRONT WHEEL DRIVE ONLY?

[hanajack]

      The idea would be to remove the main drive shaft and keep it in 4WD. 
     
      Comments?

      Problems?

[mudkicker715]

No it will destroy the transfer case after awhile

[hanajack]

     I don't know how I could get it fixed; or, get another one where I live.

     If you would indulge me, in what regard would it destroy the transfer case, and, what would be "after awhile" in terms of use/miles?

[Eagleearl]

What part of your driveshaft is bent? A driveshaft repair shop could easily replace the tube and may be able to get the ends. Someone near you may have a spare driveshaft they would be willing to sell if you post in the wanted section or they may contact you from this posting.
The viscous coupler is the only thing that keeps the differential, in the transfer case, from spinning and the car not moving, without the rear driveshaft. The viscous coupler is somewhat weak in the 119 or 129 transfer case and may fail under constant use. I have personally put thousands of miles on a 249 transfer case, with a viscous coupler, without the front driveshaft, but that is a stronger viscous coupler.
If you do run it that way make sure your parking brake is on when you park it or it will roll.

[eaglefreek]

     I don't know how I could get it fixed; or, get another one where I live.

      what would be "after awhile" in terms of use/miles?

Could be as little as a few minutes. Where do you live that it is difficult to find a drive shaft shop?

[BenM]

It's only really possible using a transfer case that allows high lock. AMC used other lengths of the same design in Jeeps so they should be common enough to come by for parts.

The length of time it will work depends on the condition of your current coupling and how aggressively you drive, but it's only designed to handle the full weight of the car for short periods before it is allowed to cool off.

[hanajack]

Hana, Maui.  Most remote place on Maui.  Three hours, a reported 620 curves and 54 one-lane bridges in the 50 miles to any repair shop.  Have had 6 accidents on  the road - only one involving another car.  No specific drive shaft service on Maui.

It's an '84 wagon,  81k orig. miles; what transfer case would it have?

I'm on a public computer and don't have my repair manual with me.  What and where is the viscous coupler at issue?

The parking brake "popped" this morning and the car went over a rock ledge, picked up a couple hundred pound rock on the way and carried it another hundred feet till the rock caught on another rock.  The drive shaft damage/bend is about 1/3 back from front u-joint.

[eaglefreek]

Hana, Maui.  Most remote place on Maui.  Three hours, a reported 620 curves and 54 one-lane bridges in the 50 miles to any repair shop.  Have had 6 accidents on  the road - only one involving another car.  No specific drive shaft service on Maui.

It's an '84 wagon,  81k orig. miles; what transfer case would it have?

I'm on a public computer and don't have my repair manual with me.  What and where is the viscous coupler at issue?

The parking brake "popped" this morning and the car went over a rock ledge, picked up a couple hundred pound rock on the way and carried it another hundred feet till the rock caught on another rock.  The drive shaft damage/bend is about 1/3 back from front u-joint.

Wow! That is remote. The viscous coupling is inside the transfer case. If the VC is damaged, you will have to take the transfer case out and disassemble it to replace the VC, which are next to impossible to come by.

[carnuck]

Sounds like you need a NP208 tcase (your current one is likely a NP129 if you have a dash mounted 2wd to 4wd switch) and a longer driveshaft (5 inches more than your current one) Jeep also uses similar shafts in the Grand Wagoneer on the front drive but they are double cardan (3 ujoints)

In the past I have made emergency repairs on driveshafts by first measuring the original shaft for length, then finding another that is slightly bigger diameter (I've even used drain pipe) and cutting out the bad part, slipping the tube of the other shaft over it and drilling through so I can put bolts through to hold it in place (I draw a line down the old shaft so I can realign the 2 halves to match) I've even welded them together that way. Just make sure the length it right first!

[ozarkrebel]

Sounds like you need a NP208 tcase (your current one is likely a NP129 if you have a dash mounted 2wd to 4wd switch) and a longer driveshaft (5 inches more than your current one) Jeep also uses similar shafts in the Grand Wagoneer on the front drive but they are double cardan (3 ujoints)

In the past I have made emergency repairs on driveshafts by first measuring the original shaft for length, then finding another that is slightly bigger diameter (I've even used drain pipe) and cutting out the bad part, slipping the tube of the other shaft over it and drilling through so I can put bolts through to hold it in place (I draw a line down the old shaft so I can realign the 2 halves to match) I've even welded them together that way. Just make sure the length it right first!

A drain pipe?  I never thought of that one, but I guess it would work in an emergency.

[carnuck]

I've even used a section of tree when one got twisted up about 40 miles from the main road (Alaska)

[ozarkrebel]

I've even used a section of tree when one got twisted up about 40 miles from the main road (Alaska)

That is a new one on me too, I bet the vibration would sure shake your money bag loose I guess when you live or break down in remote areas you have to be creative, my hats off to you for your ingenuity.

[carnuck]

Guess you didn't know my nickname was McGyver, huh? (They shot a lot of the episodes near where I grew up)

[mach1mustang351]

Not totally related but one of my good buddies back at home had a Subaru Brat ( I know there is a joke there, I have an Eagle and he had a Brat), and he had a CV axle break.  His fix was to put it in 4wd and take his outer tulips off the axles and reinstalled (to keep the hubs together) and drove it as a RWD.  He did this for many months.  He kept breaking motor mounts because of the un-engineered torquing of the engine.  This is a completely different setup but still brought up a fun memory for me. 

[txjeeptx]

Ahhh, you live on one of my favorite roads, Jack. It a long ride out to Kahului, and your Eagle won't make it that far without a rear driveshaft.

I'd recommend doing your best to straighten the driveshaft enough to use for the drive to town, where there's bound to be a welding shop that can build you a new driveshaft, maybe also get a spare built? To straighten bent driveshafts before, I've placed the shaft strategically on a couple of rocks and driven obver it with another vehicle, also used a torch and mounted the shaft in a vice. I suppose you could heat the shaft to dull glowing red with just a campfire and a vacuum cleaner(run in reverse as a blower to ge the coals hot), but I'd remove the u-joints from it, and remove as much grease as possible before trying that. Then try bending it straight using whatever immovable objects or driving over it method, protecting the tire from the heat with a board.

What bent the driveshaft? You hit a rock, or did a joint come apart?