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Discussion Starter · #1 ·
This 4x4 is driving me nuts, I put a small piece of hose on the front vac motor that locks the cad. To keep it pushed Out in the locked position. I still have no 4 wd. Any ideas does the transfer case need vac to engage the front end or is that 3 hose switch just used for locking the cad
 

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there is a switch on the t-case that has a 4 plug connector that goes into it, sounds like you might need a new one. had the same thing happen to the 92 that i use to have. the switch when out on me and it would not go into 4wd. it is on top of the t-case, i gave mine a couple of taps after i put it into 4wd and it engaged, then had do the same thing to get it out of 4wd as well.
 

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This 4x4 is driving me nuts, I put a small piece of hose on the front vac motor that locks the cad. To keep it pushed Out in the locked position. I still have no 4 wd. Any ideas does the transfer case need vac to engage the front end or is that 3 hose switch just used for locking the cad
No vacuum required for the transfer case. The piece with the four vacuum lines attached to the transfer case is a manifold of sorts.

This supplies vacuum.......
vaccum-switch-53001101-m.jpg
....to this.
vacuum.jpg
 

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Discussion Starter · #6 ·
I have the vac motor by passed keeping the cad in the locked position. Does that switch still have to work to kick the t case in to 4wd
 

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so how does the front drive shaft get power. mine is turning when i put it in 4wd but i dont think i am getting it to switch over in the motor. i am planning on pulling the shift housing out next weekend and see if there is a problem there. i may also try and trace vacuum lines out to find it there also.
 

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Discussion Starter · #10 ·
Sorry if I sound stupid but I just wanna make sure I understand, that switch has to work for the t case to turn the front drive shaft
 

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Discussion Starter · #12 ·
K thanks any way to by pass that switch? Or where this vac lines go. How does that switch in gauge the t case. I don't know much about this jeep I just bought itand it has a 350 swap, so I don't really know what the po has done or not done.
 

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The transfercase does not require vacuum to operate. Everything in the transfercase is mechanical. The mechanical linkage shifts the transfercase from 2HI to 4HI and 4LO. Their's nothing in there that requires vacuum to operate.
The vacuum switch on the transfercase just directs the vacuum to the front axle to lock in the right side axle shaft.
If you want to bypass the vacuum switch, it's easy, get yourself a Posi-Lok cable operated axle engagement kit. Or just find a TJ or XJ right side one piece axle shaft. Change some seals and there you go.:thumb:
 

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Discussion Starter · #15 ·
Thank you that's kinda what I thought but wasn't sure. If the chain in the case was broke would the case still work in 2 wd?
 

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The transfercase does not require vacuum to operate. Everything in the transfercase is mechanical. The mechanical linkage shifts the transfercase from 2HI to 4HI and 4LO. Their's nothing in there that requires vacuum to operate.
The vacuum switch on the transfercase just directs the vacuum to the front axle to lock in the right side axle shaft.
If you want to bypass the vacuum switch, it's easy, get yourself a Posi-Lok cable operated axle engagement kit. Or just find a TJ or XJ right side one piece axle shaft. Change some seals and there you go.:thumb:
This!!!

I did it with no issues whatsoever. Put in the new shafts after changing the seals, and now everything is mechanically run. No more CAD or vacuum. Takes the guess work out not getting power to the front.


Thank you that's kinda what I thought but wasn't sure. If the chain in the case was broke would the case still work in 2 wd?
Yes it will. Though I doubt yours is broken. Jack the front end up, put it in gear (or park) engage the 4wd and try to spin the wheel. This should result in the wheels not freely spinning.
 

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The transfercase does not require vacuum to operate. Everything in the transfercase is mechanical. The mechanical linkage shifts the transfercase from 2HI to 4HI and 4LO. Their's nothing in there that requires vacuum to operate.
The vacuum switch on the transfercase just directs the vacuum to the front axle to lock in the right side axle shaft.
If you want to bypass the vacuum switch, it's easy, get yourself a Posi-Lok cable operated axle engagement kit. Or just find a TJ or XJ right side one piece axle shaft. Change some seals and there you go.:thumb:


X2
I run the cable type lock on the CAD, Posi-Lok, it's not too much work to pull the CAD and check the shift fork, it may be bad.

there are two vac lines on the CAD one pulls it in, and the other pulls it out, if you are bypassing the switch on the transfer case with just one vac hose try one side of the CAD and then the other.
I ran mine by-passed for a month are two before the Posi-Lok, It will work that way if the CAD is engaging both axle half's.
 

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Get all four wheels in the air, put it in Four wheel drive and start, have it idle, one wheel front and back should be spinning. at the very least your front drive shaft should be spinning. The most likely issue with 4 wheel drive is the center axle disconnect not working. This can be caused by a few things, (the switch in the transfer case being one potential problem) vacuum leaks being another. There is a sticky at the top of the forum list that talks about an easy way to bypass the center axle disconnect. http://www.wranglerforum.com/f8/vacuum-shift-motor-inexpensive-fix-w-pics-127405.html
 

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Well looks like I'll be going for a t case. Wheells spin freewht locked in 4 wd
:confused: I'd check a lot of things before I'd go for a case. pull the CAD, pull the front axle cover, are you sure you need a new transfer case?
 
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