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Unread 08-06-2012, 12:25 AM   #1
mitch19245
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quadratrac in emergency drive. help

i think my 78 cj7 with a quadratic is stuck in emergency drive, if it was in normal and i lifted one front tire off the ground then that tire would just spin and the jeep would not go anywhere, right? when i do that the jeep goes forward. i get 6 mpg so if its in e-drive all the time won't it kill my gas milage?

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Unread 08-06-2012, 12:54 AM   #2
mitch19245
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when i lift both front wheels off the ground and try and drive it it just nocks over the jack stands, if it was in normal shouldn't it just spin the front 2 tires and not try and drive?
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Unread 08-06-2012, 01:13 AM   #3
mitch19245
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also when i turn sharp and slow you can hear like a weird rubbing noise almost like the tires rubbing but i know they aren't rubbing.
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Unread 08-06-2012, 02:29 AM   #4
gunzmcghee
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No offense, but this thread makes no sense. You will get more responses if you kinda give us an idea of what's going on here.. I'm assuming you are saying its stuck in 4wd all the time correct... If so all four wheels need to be off the ground. preferably not airborn, but on jack stands. the transmission needs to be in neutral, but the engine does not need to be running. there are two tubes that go into the top of each axle housing, one is the axle breather. it is a rubber hose that goes up to the frame and has a metal cap on it. the other is for the actuator. rotate one wheel on the front axle and watch what direction the other wheel turns. do the same on the rear axle. if both are turning the same direction the posi-trac is locked in. try spinning the front wheel as if the vehicle was moving forward, and then snap it backward real fast. if you hear a clunk from inside the differential it should have unlocked. if it does spin the opposite the axle is unlocked. if it doesn't, then vacuum needs to be applied to the actuator to disengage it. most four wheel drives require you back up the vehicle to unlock the differentials. hope this helps, good luck
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Unread 08-06-2012, 06:05 AM   #5
jeepdaddy2000
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Quote:
Originally Posted by mitch19245 View Post
when i lift both front wheels off the ground and try and drive it it just nocks over the jack stands, if it was in normal shouldn't it just spin the front 2 tires and not try and drive?
With both front tires off the ground, lock up the e brake and try again. If the engine bogs and the rig doesn't move, then chances are the e drive is locked (this should provide more than enough resistance to overcome the LS in the t case).
If this is the case, you will need to inspect all the vacuum lines, and insure there is vacuum to the t case locking motor. If all is good, then the diaphragm in the motor is bad, or the fork/rail/collar is jammed, or the LS unit is damaged.
If it is locked, do not drive it on pavement. A fully locked 4X4 on hard surfaces will create an undue amount of "wind up", stressing the drivetrain and possibly causing damage.
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Unread 08-06-2012, 08:06 AM   #6
lucdog
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If you haven't already, read this, it's good info http://jubileejeeps.org/quadratrac/

There are 2 ways to access the vacuum actuator.

1. Remove the transfer case from the transmission .
2. Cut a access hole in the floor of the jeep.

Before doing either of those, I would check all the vacuum lines associated with the TC. If the vac.ines are factory they should be color coded. The 30+ year old switch/valve in the glove box would also be suspect.

While looking at the link, notice the apply and release sides of the actuator.The lines running to the TC are very small. So it's hard to "feel" vacuum with your finger if you pull a line off.

After checking all the lines, and not finding a problem. My next step would be to run a dedicated vacuum line from full manifold vacuum, to the release side of the actuator. This bypasses all the other lines and the switch/valve.
With a known good source of vacuum at the actuator, rock the jeep back and forth a bit in case of any binding.

Another problem could be the absence of the proper fluid in the TC, this could cause the cone clutches in the TC to not work as there suposed to.

On the plus side, if you need to remove the TC, it's probably the easiest Jeep TC of all of them to remove, remove the low range unit first, it makes it lighter. Also pay special attention when fling the TC/low range with fluid, if not done correctly, it's easy to overfill.

Bill
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1979 CJ7 360, TH400/Quadratrac trail Jeep.
1979 J20
1980 CJ5 trail Jeep.
1983 CJ7 pretty weekend and sometimes to work Driver in the summer, My first rebuild, if the Q-trac and 5 are broke, this one is the one to take. its just as capable as the other 2, except nice paint.
1984 Grand Wagoneer, 1 ton axles, great 360/727, and a big a$& tree fell on it .
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Unread 08-06-2012, 04:57 PM   #7
gojeepin
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Quote:
Originally Posted by mitch19245 View Post
i think my 78 cj7 with a quadratic is stuck in emergency drive, if it was in normal and i lifted one front tire off the ground then that tire would just spin and the jeep would not go anywhere, right? when i do that the jeep goes forward. i get 6 mpg so if its in e-drive all the time won't it kill my gas milage?
Your transfer case is full time 4-wheel drive. As stated before the transfer case is limited-slip in normal mode ... not open. So it differentiates between the front axle and rear as long as the difference isn't enough for the friction clutches to engage. The limited-slip clutches should be enough to spin the wheels in your test unless they are worn out.

The only real difference is the Emergency Mode locks the front and rear output shafts like a locker vs a limited slip.
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Vibration? Bump steer? Wandering? Read: Steering, suspension, and driveline basics. An article on how it works and where to look for problems.

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Unread 08-06-2012, 11:42 PM   #8
mitch19245
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If i took out the front drive shaft and it is in normal drive then it shouldn't go anywhere right?
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Unread 08-07-2012, 05:53 AM   #9
lucdog
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Quote:
Originally Posted by mitch19245
If i took out the front drive shaft and it is in normal drive then it shouldn't go anywhere right?
That is correct, if it's in emergency drive it will move. The transfer case end of the front shaft is not the easiest to remove. There are 4 bolts that come thru the yoke that hold the shaft. If you lower the skid plate, support the TC with a jack stand.

Bill
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1957 WILLYS pickup, needs work.
1973 J 4000,
1978 CJ7 DD.
1979 CJ7 360, TH400/Quadratrac trail Jeep.
1979 J20
1980 CJ5 trail Jeep.
1983 CJ7 pretty weekend and sometimes to work Driver in the summer, My first rebuild, if the Q-trac and 5 are broke, this one is the one to take. its just as capable as the other 2, except nice paint.
1984 Grand Wagoneer, 1 ton axles, great 360/727, and a big a$& tree fell on it .
1989 YJ the CJ to YJ conversion.
2005 TJ Rubicon.
2011 Grand Cherokee Laredo 4x4, Mrs. LUCDOG's DD.
Lots of parts not for sale, i'm a hoarder.
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Unread 08-07-2012, 05:56 AM   #10
bigredisb
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Correct. It should transfer power through the diff to the front yoke. Some times it's easier to zip the bolts out of your drive flanges (where lock outs would be on a non q trac jeep) and remove them. The q trac front shaft is a pain to remove.
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Unread 08-07-2012, 06:05 AM   #11
lucdog
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Quote:
Originally Posted by bigredisb
Correct. It should transfer power through the diff to the front yoke. Some times it's easier to zip the bolts out of your drive flanges (where lock outs would be on a non q trac jeep) and remove them. The q trac front shaft is a pain to remove.
Good point Bigred. I have lockouts on mine and forgot about that.

Bill
__________________
1957 WILLYS pickup, needs work.
1973 J 4000,
1978 CJ7 DD.
1979 CJ7 360, TH400/Quadratrac trail Jeep.
1979 J20
1980 CJ5 trail Jeep.
1983 CJ7 pretty weekend and sometimes to work Driver in the summer, My first rebuild, if the Q-trac and 5 are broke, this one is the one to take. its just as capable as the other 2, except nice paint.
1984 Grand Wagoneer, 1 ton axles, great 360/727, and a big a$& tree fell on it .
1989 YJ the CJ to YJ conversion.
2005 TJ Rubicon.
2011 Grand Cherokee Laredo 4x4, Mrs. LUCDOG's DD.
Lots of parts not for sale, i'm a hoarder.
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Unread 08-07-2012, 06:33 AM   #12
gojeepin
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If the transfer case clutches still work it will attempt to move a little. like any limited slip, it won't be able to overcome much resistance.

You'll definitely know if it's in emergency mode or not.
__________________
Vibration? Bump steer? Wandering? Read: Steering, suspension, and driveline basics. An article on how it works and where to look for problems.

83 CJ7, 4.1L 6cyl (4.0L bored .030" over), 35" tires, T-5 transmission, Dana 300 TC, Trussed AMC 20.
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