Rear end acted up after manuallel putting car into 4 wheel drive.

[Eagle1984]

The diagram I gave my buddy should still be up on http://oljeep.com The Jeep diagrams for the GW are almost identical for your setup. Jeep made it way more complicated than it needed to be. By '86 they fixed that by doing away with the vacuum front axle (like they were originally in '80/81 except 2wd was still possible)

Best setup: Vacuum from motor to reservoir. From reservoir to switch. 2 lines on switch (2wd and 4x4) Flip switch and vacuum goes to tcase vacuum motor, pulling it into 4x4. (this is with a locked or non-vacuum front diff) Flipping switch other way moves tcase vacuum motor to 2wd position. Best part? It is now shift on the fly!

Thanks, as for the best set up I am not sure what you mean, do you have a diagram of it. Would not mind trying that. The one on the site I need is the 1983/1984 vacuum front axle and vacuum system diagram right. Been driving her again and was wondering when I but her in gear there is a rumbling noise that come from the car but only in 4 wheel drive, also I only hear it when I am sitting still or waiting to make a turn, if I am moving I do not hear it as much. The engine runs fine but the car sounds different. Is that how it is supposed to sound in 4 wheel Drive? Sorry for the questions just be cautious as this is the first Eagle I have owned so not sure what is normal.

[carnuck]

Have you checked the diff and tcase oils? Best set up is permalocked front diff and vacuum to/from shifter motor on trans only (same as '86 to '88)

[Eagle1984]

Have you checked the diff and tcase oils? Best set up is permalocked front diff and vacuum to/from shifter motor on trans only (same as '86 to '88)

I should also mention that the car seems to vibrate too, when it is rumbling. Is there a dipstick for the diff and tcase oils in the engine compartment like for the engine oil or are they on the parts themselves?

[mudkicker715]

Inspection covers midway up. I doubt that is it. Check for driveline looseness.

[Eagle1984]

Inspection covers midway up. I doubt that is it. Check for driveline looseness.

What do you mean exactly by Driveline looseness. How would I check for it.

[BenM]

Put the car up on 4 jacks, put the transmission in neutral. Spin all the wheels one at a time, see if one is significantly tighter then the others or makes noise. The front should drag more then the back, but not by a lot. If both back wheels make the differential click, then it may be the spider gears.

Also go under and turn the driveshafts. You will get a small amount of rotational play, but if the driveshaft clicks or grabs unevenly, or feels loose then you have a bad universal joint.

The transfer case has two big hex nuts on it, I usually use a crescent wrench on them, they should NOT be tighter then that, they're fill and drain plugs with washers into aluminum. Don't ape them on when you're done. You'll have to remove the skid plate.

You should be able to put your finger in the top plug and feel oil within 1/4" of the top, if not add some. Either get an assistant and a long hose or a hand pump to fill it, there's no room to tilt a bottle under there. Dextron is spec'ed for it, it's about 5w-20 equivalent motor oil. Early transfer cases spec'ed 10w30, but it was too thick and caused problems.

A vibration is probably between the transfer case and the road unless your transmission mount is shot, but it's a good idea to check the fluids while you're down there. You may want to check the differentials while you're under the car, they should be filled to the same standard, just under the bottom of the filler plug, with 75w-90 GL-5.

[Eagle1984]

Put the car up on 4 jacks, put the transmission in neutral. Spin all the wheels one at a time, see if one is significantly tighter then the others or makes noise. The front should drag more then the back, but not by a lot. If both back wheels make the differential click, then it may be the spider gears.

Also go under and turn the driveshafts. You will get a small amount of rotational play, but if the driveshaft clicks or grabs unevenly, or feels loose then you have a bad universal joint.

The transfer case has two big hex nuts on it, I usually use a crescent wrench on them, they should NOT be tighter then that, they're fill and drain plugs with washers into aluminum. Don't ape them on when you're done. You'll have to remove the skid plate.

You should be able to put your finger in the top plug and feel oil within 1/4" of the top, if not add some. Either get an assistant and a long hose or a hand pump to fill it, there's no room to tilt a bottle under there. Dextron is spec'ed for it, it's about 5w-20 equivalent motor oil. Early transfer cases spec'ed 10w30, but it was too thick and caused problems.

A vibration is probably between the transfer case and the road unless your transmission mount is shot, but it's a good idea to check the fluids while you're down there. You may want to check the differentials while you're under the car, they should be filled to the same standard, just under the bottom of the filler plug, with 75w-90 GL-5.

Thanks, so is a vibration normal? What would happen if I continue to drive it this way? Now I seem to be hearing a slight squeaking noise coming from the engine compartment but also only when I am in gear and stopped at a stop light, like the vibrating.

[GRONK]

You don't have mismatched tires do you?

[Eagle1984]

You don't have mismatched tires do you?

I will have to go to check that. I know the left rear passenger leaf spring is shot but I doubt that would cause a problem.

[Hawk258]

I have a silly question, but have you tried just swapping to a cable style activation system? At least then you would have a way of testing the system and having a slightly more relible system in the future.

[captspillane]

What you are experiencing is completely normal. I used to keep a 9/16 wrench in the glove compartment of all my Eagles for this reason. It was actually pretty silly of you to bring your car to a mechanic each time. I have had to crawl under my car at least a dozen times to reach up, put the 9/16 wrench on the transfer case lever, and push it back into the engaged position. When it happens the car revs up, acts likes it wants to move but can't, and then doesn't move. I eventually ripped the vacuum diaphragm out of the way and used rope to pull a slight tension against the hole the linkage used to connect to. It stays in just fine with just a little bit of pressure.

Do not overreact to people saying that you could have burned out a viscous coupling. Fact is that everyone is running burned out viscous couplings. They only last a few years and are designed to be changed out as often as you change clutchs, about 60K miles. It doesn't really do much and there really isn't much difference between the Eagle transfer cases that had them and the ones that didn't. Once it stops working you have an open differential between the front and rear yokes, which is why you have to keep the front from spinning freely if you want the back output to push you forward.

If you switch transfer cases, make sure to get a Cherokee low range unit. The select-trac designation means that it has an open differential or viscous coupling and the command-trac NP231 has a closed differential. All have the low range locked into a closed differential. Even if you run a 231 with the front and rear outputs locked together, you will not notice any major wear because the open differentials in the front and rear willl take up the slack. Its recommended to stick with the viscous coupling because in a Cheroke the front U joints will make a severe vibration at higway speeds if you're locked into four wheel drive. The CV shafts and independent front suspsnsion on an Eagle doesn't suffer those woes.

Don't hesitate to keep your Eagle in 4WD. It was designed to be all wheel drive before customers knew what all wheel drive was. There is no appreciable difference in gas mileage and its not worth the hassle to fix the vacuum switches. Just lock them in 4 WD and go on your merry way.

[Eagle1984]

What you are experiencing is completely normal. I used to keep a 9/16 wrench in the glove compartment of all my Eagles for this reason. It was actually pretty silly of you to bring your car to a mechanic each time. I have had to crawl under my car at least a dozen times to reach up, put the 9/16 wrench on the transfer case lever, and push it back into the engaged position. When it happens the car revs up, acts likes it wants to move but can't, and then doesn't move. I eventually ripped the vacuum diaphragm out of the way and used rope to pull a slight tension against the hole the linkage used to connect to. It stays in just fine with just a little bit of pressure.

Do not overreact to people saying that you could have burned out a viscous coupling. Fact is that everyone is running burned out viscous couplings. They only last a few years and are designed to be changed out as often as you change clutchs, about 60K miles. It doesn't really do much and there really isn't much difference between the Eagle transfer cases that had them and the ones that didn't. Once it stops working you have an open differential between the front and rear yokes, which is why you have to keep the front from spinning freely if you want the back output to push you forward.

If you switch transfer cases, make sure to get a Cherokee low range unit. The select-trac designation means that it has an open differential or viscous coupling and the command-trac NP231 has a closed differential. All have the low range locked into a closed differential. Even if you run a 231 with the front and rear outputs locked together, you will not notice any major wear because the open differentials in the front and rear willl take up the slack. Its recommended to stick with the viscous coupling because in a Cheroke the front U joints will make a severe vibration at higway speeds if you're locked into four wheel drive. The CV shafts and independent front suspsnsion on an Eagle doesn't suffer those woes.

Don't hesitate to keep your Eagle in 4WD. It was designed to be all wheel drive before customers knew what all wheel drive was. There is no appreciable difference in gas mileage and its not worth the hassle to fix the vacuum switches. Just lock them in 4 WD and go on your merry way.

So basically you are saying I should forget about repairing the vacuum system because it is a pain, which is how I feel and just put a piece of wire the form the switch to the lever on the transfer case and tie it in the engaged position, what is the best way to brace the lever to keep it engaged. Also I think I will keep it in 4 wheel drive, seeing as the mechanic charged $130 to change it the first time. Though I might have asked this already if I put in the 119 and the front does disengage will it cause any damage? and the vibrating is normal? sorry for all the question put this is the first car I have ever really tried to work on not really good mechanistically yet. Also with the cable through the floor how do you keep water from getting in where the hole is? also what do you mean exactly by  "Once it stops working you have an open differential between the front and rear yokes, which is why you have to keep the front from spinning freely if you want the back output to push you forward."

[captspillane]

Vibrating and wierd noises is a normal part of owning a 25 year old car, but they should always be looked at. Ideally there would never be any and some are harmless and others are not. It took at least three years of active witch-hunting to be able to drive my red SX4 without any squeaks or clunks. Good luck.

If you are under the car, you can look up on the drivers side of the car and see the front driveshaft attached to the yoke on the transfer case. Between the driveshaft and the side of the transmission is the vacuum diaphragm. Its round plastic with a metal rod sticking out of it. That rod is in an L shape, with the short part of the L poking through a flat piece of metal about three inches long. On the opposite end of that short piece of metal is a nut that accepts a 9/16 wrench. You put your wrench on that nut and twist it clockwise. The three inch piece of metal will rotate rearward toward the transfer case. It will noticeably click into place. Sometimes you need to reach up with your other hand and jiggle the driveshaft to get it to line up and click. That's what your mechanic did at a cost of over a hundred dollars. At the top of the three inch lever you can pop the rod out of place or just tie to the rod with rope, and then tie the other end of the rope to anything rearward of the lever. You do not need to drill anything or to put any holes in the floor. All the old vacuum lines can be removed if you plug them from leaking and ruining your idle. The shift switch on your dash will just be decorational. I am pretty sure it was clockwise for 4WD, but it may have been counterclockwise. I'm not home to double check.

[Eagle1984]

Vibrating and wierd noises is a normal part of owning a 25 year old car, but they should always be looked at. There should never be any and some are harmless and others are not.

If you are under the car, you can look up on the drivers side of the car and see the front driveshaft attached to the yoke on the transfer case. Between the driveshaft and the side of the transmission is the vacuum diaphragm. Its round plastic with a metal rod sticking out of it. That rod is in an L shape, with the short part of the L poking through a flat piece of metal about three inches long. On the opposite end of that short piece of metal is a nut that accepts a 9/16 wrench. You put your wrench on that nut and twist it clockwise. The three inch piece of metal will rotate rearward toward the transfer case. It will noticeably click into place. Sometimes you need to reach up with your other hand and jiggle the driveshaft to get it to line up and click. At the top of the three inch lever you can pop the rod out of place or just tie to the rod with rope, and then tie the other end of the rope to anything rearward of the lever. You do not need to drill anything or to put any holes in the floor. All the old vacuum lines can be removed if you plug them from leaking and ruining your idle. The shift switch on your dash will just be decorational. I am pretty sure it was clockwise for 4WD, but it may have been counterclockwise. I'm not home to double check.

Thanks, I never knew the clutch is supposed to be changed ever 60 thousand miles. Also how long could I put off the vibrating. I am currently in college and my usual mechanic is a 1.5 hour plus drive. Laverne is my daily driver.

[captspillane]

To explain my statement, let me explain what an open differential is. Imagine an axle sitting on the ground with no driveshaft or tires attached to it. If you twist the driveshaft yoke while holding one hub still, the other hub will spin. If you hold the driveshaft yoke still while spinning one hub, the other hub will spin in the opposite direction. If any one input or output is spinning, another input or output must also spin, but the third input or output can stay perfectly still. In your transfer case you have an input shaft coming from the transmission, an output shaft going to the rear driveshaft, and an output going to the front driveshaft. If you spin the input shaft and hold one output still, the other output must spin. If you hold the input shaft still, like when the transmission is in park, then the rear wheels can only spin forward if the front wheels spin backwards. So if you put the transmission in gear and apply engine torque to make the transmission output shaft spin, then the input shaft of the transfer case will spin, and one of the output shafts must also spin but the other output shaft has the option of sitting still. When your front wheels are no longer connected to the front driveshaft because of the front axle disconnect, the front driveshaft spins effortlessly while the rear driveshaft can only spin if the car moves forward. Your car won't move anywhere because the engine torque took the path of least resistance. In the same way your car will not move in 2wd if one rear tire is up in the air. The tire on the ground takes effort to spin, so it stays still while the other tire spins with the rear driveshaft. It does not damage anything if the front disconnects when you don't want it to, but the car might not move anymore.

In low range or with a "command-trac" transfer case, the differential is closed or locked. That means that if the rear driveshaft spins, the front driveshaft must also spin. It also means that if the input shaft spins, both outputs must spin together too. It wouldn't matter if the front driveshaft was removed or disconnected from the front wheels with a closed differential.