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Discussion Starter #1
Ok, once and for all, please explain plainly for everyone why it is not good to remove the front driveshaft off of a 249(AWD) transfer case. And please explain for everyone what happens inside the case if you remove it. I found this:

AndyZJ said:
My whole thing with removing the front driveshaft is that it causes uneven load on the chain and output shafts. I've known a few cases where the Tcase has basically self distructed as it is still sending load to the front output yoke where there is nothing there. It binds up and then the chain becomes floppy. I'm pretty sure that its also not good for the VC since since it is always then sensing a variance in load from the front end. If you plan on using the 249 again, then its really not good for the Tcase.
 

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From what I understand it's bad to remove the front shaft from 93-95. I believe it's bad for the VC not the TC itself. From 96 - 98 it seems they used a different pump or something.....might have something to do with those years having an actual low lock. I'm not an expert. The only other bad thing about removing the front shaft is when you park...the pump will lose pressure and release the driveline and your rig could roll away.
 

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This is what I've found while overhauling my '98 249:
In a nutshell, The '96-'98 249 has essentially a straight shaft (made up of two seperate shafts) from the input side to the rear output yoke. These two shafts are "locked" together when the transfercase is in high range and the VC takes care of any speed differential between the front driveshaft and the rear one. In low range the VC itself is locked and taken out of the equation.
It is on this "main" shaft that the VC resides. The ID of the VC is splined to the shaft and the outside of the VC is connected to the front output shaft by the chain.
Keep in mind that the VC is very stiff and is very difficult to turn by hand. If the front driveshaft is out, the VC simply turns on it's shaft and easily turns the chain driving the front output yoke. It never locks up because there is no shearing action to heat up the fluid. It just spins because there is not enough resistance to make it slip. You have to have both driveshafts in and turning at relatively different rpm's in order to get the shearing action in the VC which heats up the fluid and causes it to lock up.
This is only for the '96-'98 249. In high range all the torque to the front wheels is transferred through the VC.
On the '93-'95 249 the VC acts on a planetary gearset which transfers the torque. The input shaft and the rear output shaft are not locked together. That's why these tend to burn up the VC and will roll if left in "park" when the front driveshaft is out.

This is just my opinion from first hand experience at taking a 249 apart.
 

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Discussion Starter #4
85IrocZ-28 said:
All time 4x4. Think of it this way...If you park on a hill with a 2 wheel drive car and the right tire is in the gutter on ice, it can roll backwards. While the left tire on dry pavement is rolling backwards, the right tire is actually rolling forward and pilling out on the ice.
Now apply this to the jeep...When the front driveshaft is out, tires can spin independently. The front tires are not going to prevent rolling at all because the driveshaft is gone.
If the VC is going out, when it cools down it will allow the front driveshaft output to slip with respect to the rear driveshaft output. So the rear tires can roll on the pavement while the front output shaft spins freely in the air because the stationary front axle is not connected and cannot prevent the front output shaft from spinning.
I have not only seen this happen to others, but it has also happened on my ZJ. It isn't fun to come out of the store and find the jeep in the middle of the road.
I really don't think that this will net much benefit on mpg. Unless you have changed your front axle and have locking/unlocking hubs... while you are driving down the road, both axle shafts are still spinning. The diff is still spinning as well. The only thing in your drivetrain that is no longer sucking gas milage is a rotating front driveshaft that doesn't weigh that much. I think a better solution to milage is to take it easy on the throttle.
If you are set on running without it, I recommend setting your park break very tight. I share my experiences so that others don't have to see the same crazy things that I have. I would hate for someone's jeep damaged from rolling while parked. Luckily mine didn't hit anything.
 

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Simply put.

It is a diff, if one tire spins on a open diff the other doesn't go anywhere. Yes it will burn it up if you try to do it, I have learnt this from experience.
 

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its bad. jeep had a recall cause grands with the 5.2 and 249 came with a space saver spare. so when you had a flat tire, you put on the spare and you could get about 50 miles before you needed a tire repaired and a new viscous coupler. i dont believe anyone that says they run without a driveshaft without issue.
 

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Geez i sure hope i wasn't talking out my arse on this one. All i have ever heard is that if it is designed to run 4 wheels, don't re-invent the wheel.
 

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think about this, when you put your transmission in park you are in a sence locking it from moving correct? well, when you lock it from moving how in the heck is the driveshaft going to move. on the 249 the front and rear turn together, when you remove the front driveshaft the front output will still spin like as if the driveshaft is still there. the rear will spin also, but when you put your tranny into park it cannot move. just cause the fronts not there doesnt mean the rear isnt going to lock. i have been running my 5.9 for almost 9 months without a front driveshaft with absolutely no problems. i have smoked my tires off in 1st thru 3rd gear and still have no issues. a good friend of mine has a 5.2 he removed the fornt driveshaft on his for awhile also had no issues.
 

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with the front driveshaft out, the vc is constantly slipping. i wonder if you were to reinstall the front driveshaft if the vc would be locked up and chatter like mad on turns.
 

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For what it's worth, my first 5.9 blew out the driveshaft and I drove it around for a month or so without the driveshaft in it. I even took in on 200 plus trips in 2wd. When I put the new driveshaft back in it, it didn't complain a bit. I didn't know there could be an issue with not having it in but there was not a blatant problem with it when I put it back in. Maybe I just got lucky.
 

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YETI - The Abominable WJ
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From what has been said, there are differences in the T-cases. I didn't know this, so the newer ones (96 and up) may not have this problem. Someone chime in if you have had this problem with a newer t-case.

Here is why it will roll in park. We need to think of the VC as a differential. If you jack up the rear end of a rear wheel drive car, and it is in PARK, you can still get the tires to rotate. If you rotate the tire on one side, the other will rotate in the opposite direction...even though it is in park. The transmission is locked, the drive line is locked, but the rotation from one tire can be transferred through the differential to the opposite tire. If you take out an axle shaft and cut it in half and reinstall it, you can park on a hill and the car will roll backwards. The cut shaft section that is inside of the differential will spin freely while both tires are rolling backwards.

In the Jeep, think of the VC as a differential. If you cut one side of the axle (take out the drive shaft) and leave the other one connected, the car will still roll in park. The transmission is locked in park. But the rear drive shaft can rotate and allow the car to move because the VC (acting like a differential that applies different speeds and power to the different wheels) doesn't have anything else on the other side of it to stop it from spinning. So nothing in the transmission moves because it is in park. But the front and rear output shafts (which are connected through the VC) can still spin. Again, the VC is acting like a differential and can spin even when everything else in front of it in the transmission is locked down from moving.

Putting a transmission in park doesn't lock your tires, it locks the entire system that sends power to your tires. If parts are missing from the system that will allow independent movement between tires, problems can occur.

I am not an expert on the internal workings of the t-case. I don't know if this is only a problem in the older 93-95 t-cases. But this does happen. I am not sure if running without a front ds will damage the VC. I have seen two different GC's roll with the front drive shaft out while they were in park.
 

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ive found real world experience is worth twice as much as book knowledge. i guess its kind of hard to dispute someone who has disproved the masses. sounds like i stank corrected, but it makes you think, its bad for a vc to have the wrong size tire on but ok to just run the back. who'd have thought!
 

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I have had my front driveshaft out in my 98 for 3 years I drop the driveshaft in b4 the 1st snowfall & remove it in march & I think it has extended the life of the vc (now have 151k) but am swaping the case out to a 39k case I found from a 5.9
a co worker has a 94 & I heard him pulling in a spot & the tires were chirping & told him he may pop a u jount or his diff & he pulled the shaft & the truck has rolled 2 times in the last mo ( he now uses his e brake)
but at least he can turn
 

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I just swapped my 98 249 into my sister's 95 and here's what I found, the early 249 mainshaft has a planetary like a 242 so the front and rear are never really connected. The late 249 has a solid mainshaft from the front planetary all the way to the rear d-shaft and when shifted into low range the VC is no longer part of the equation. I will be pulling the 98 case again this weekend to install a new VC and post pictures of the two side by side. Looking at the internal's it doesn't seem like you should be able to damage the VC in a newer case with the front shaft pulled.
 

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i ran my old grand w/o the front shaft for MONTHS, wicked cool burnouts, and not a problem EVER. just not real torque like it did in awd. lol 4low both shafts u can hop the front end a ways up there if u try hard enuf.
 

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alright so I want to know for sure. My vc is basically done for and am going to buy a new one to put in the 249, but I won't have the funds for awhile. If I take the front driveshaft out will I hurt anything? I don't care about hurting the vc because it's done for anyways, but will anything go wrong with my tcase? I have a 97 zj laredo. thanks.
 

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I believe the 96 up is locked front to rear, so it may not matter. It seems that those who haven't had any problems when removing the driveline had the newer 249... the newer locking 249 t-case. The 95 and older 249 doesn't lock fron to rear. If you remove the front driveline from one, you will roll. This is what I have gathered from the comments that have been made about the internal workings. But I don't have experience with t-cases like others on this site.

Either way, I would use your e-brake. I drove for a while with my VC going bad. Even made two 600 mile round trips. It felt like crap right after getting off of the interstate, but was ok after it cooled down. How bad is it? If it really isn't that bad, just leave the driveline in till you get a new case or a new VC.
 

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I just want to add to this, that i decided to try out removing the front driveshaft on my '93 GC. Well the only thing that i can say definitely is that the acceleration seemed to be off. As if it were trying to compensate for the front driveshaft being removed, it was MORE sluggish on acceleration and didn't seem to want to GO. Reinstalled the driveshaft and it went away.

Also, my GC rolled down a hill while in park and i luckily noticed it happening before it hit anything.
 
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