does vaccum bottle affect 4wheel drive?

Just like it says. I tossed mine and have the front disco 30. It still shifts into 4 wheel but i have heard that it will affect it. I have searched the forums for more specific info but have found none.

I had a disco 30 on my 87' and I took the dingle ball off, and the 4x4 didn't work, because the disconect is ran by vacuum. I remounted it like up on the passanger side of the firewall. (because I took off the bumper)
uke:
-Patrick

The thing is it still works, so i am wondering if it really did affect it.

Do you still have it? If you do...I want it...I cut mine and now all I have is defrost

DOOD said:

The thing is it still works, so i am wondering if it really did affect it.

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DOOD said:

Just like it says. I tossed mine and have the front disco 30. It still shifts into 4 wheel but i have heard that it will affect it. I have searched the forums for more specific info but have found none.

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The transfer case will still shift into 4wd without the vaccum system. However the front axle disconnect will not engage.... so while your t-case is now in 4wd, your axles are still in 2wd

Get a posi lok cable to replace it.

No, what I am saying is the front axle still engages. How would it still engage without the vacumm bottle?

Poke your head under there and check to see if you even have a vaccum disco front axle, chances are that you don't if it still engages... My 89' has a non disco d30... They were much more common with the np242 case. Though i've seen several on np231 equipped XJ's.

Enough said.

No, it is the vacumm disco axle, it is the high pinion with a rubber hose attached to the outlet on the high point on the housing. It is a '91 4.0 np231 automatico.

I have a '88 model that does have the disco d30....

Mine never unlocks....no matter where i put the tcase shifter.

It comes outta 4wd but the front axle never unlocks...

does your disengage and then engage (as in does it work properly?)

also...I don't remember the vacuum lines running to the vacuum bottle...

Its been awhile since I've looked at it...but I thought the vacuum line ran to the tcase....


am I wrong?

The vac lines to the disco do not run into the top of the diff housing, that's a vent tube.

There SHOULD be a plate on the passenger side axle tube, just below the passenger upper control arm mount that houses the disconnect motor.. If there are vaccum lines running into it, then you have the disco front axle.. If not, then you don't.

The rubber hose to the top of the diff housing is not a vaccum line.

Yes it does disengage then engage properly...as in when i shift from 2wd to 4wd and back it works. I am just wondering then does this really affect it.

Oh dude you are awesome thanks for the info... that is such a relief.

DOOD said:

No, it is the vacumm disco axle, it is the high pinion with a rubber hose attached to the outlet on the high point on the housing. It is a '91 4.0 np231 automatico.

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are you sure? that sounds like the vent tube you're describing.

the vaccum disco is on the passenger (right) side of the axle, just below the upper control arm mount

I just took apart the vac motor system on my 88 Chief this weekend. So I can tell you this. As I know there are several things to check regarding the engagement/disengagement of a Dana 30...
First what I did was to put the transfer case into 4hi(with the engine running)... then chock the rear wheels and jack up the passenger side of the axle. turn your front drive shaft. if it does not turn then your transfer case is indeed activated. then go to the passenger tire and turn it. if it does not turn then indeed your four wheel is engaged. If the front wheel spins there are several things to look at. get a vac guage and check that you are getting vac at all three hoses. White is for the indicator lights on the dash. Yellow is to engage the vac motor. Green is to disengage the vac motor. if you are getting propper vac then most likely the fork that engages the axle is cracked or broken. remove the front tire(for ease of operation) jack the axle up a bit higher(passenger side) remove the two bolts that hold on the crecent shaped protector for the vac motor. Put an oil bucket under the vac motor housing and remove the four bolts that hold on the housing. remove and check fork for any stress cracks or actual snappage. replace whats broke, scrape off the old gasket reseal with permatex and away you go

DOOD said:

No, it is the vacumm disco axle, it is the high pinion with a rubber hose attached to the outlet on the high point on the housing. It is a '91 4.0 np231 automatico.

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that rubber hose is the vent line. look on the passenger side of the axle for the disconnect.

IIRC, the vacuum disconnect axle is very obvious just by looking at it. There's a square metal box on top of the tube with lines running to it. If you don't have this extra box, you don't have a vacuum disconnect axle.

fubar XJ said:

IIRC, the vacuum disconnect axle is very obvious just by looking at it. There's a square metal box on top of the tube with lines running to it. If you don't have this extra box, you don't have a vacuum disconnect axle.

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I agree. I just bought a vac disco axle with 4.10's to throw under my 94. I obviously don't have a vac disco on my Jeep, so when I saw it I was going WTF is that thing?

Of course I'm just gonna throw a posi lok cable on and call it a day.

IslanderOffRoad said:

are you sure? that sounds like the vent tube you're describing.

the vaccum disco is on the passenger (right) side of the axle, just below the upper control arm mount

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Gee that sounds nearly identical to my answer...

Good job!

nekocopter said:

Gee that sounds nearly identical to my answer...

Good job!

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if i know the answer, i don't always read the posts after the question