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post #1 of (permalink) Old 12-16-2000, 06:22 PM Thread Starter
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axle disconect on YJ Dana 30

I was wondering if anybody could tell me what all the vac lines on the axle shifting motor do. I want to know because on my way home from work the front axle disconected a couple of times. I was driving up a very icy hill and poof, no more four wheel drive.(It scaredd the $hit out of me and I almost lost it). But when I got to the top it was fine. Now since its so cold outside I just crawled under there and check the lines and they were on the axle and wheren't loose.I never checked if they were leaking anywhere but will do this tonight. I just want to know what they all do and where they are fed from. Thanks

I need to get a girlfriend I'm getting to close to my jeep.
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post #2 of (permalink) Old 12-16-2000, 09:55 PM
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Re: axle disconect on YJ Dana 30

Well, what would you know... I'm new to jeeping myself but this was one of the first thing we had to fix on my buddys rig. Basically, you have vacuum routed from the manifold to the vacuum switch on the top part of the transfer case. From here it goes to the vacuum shift motor on the front axle. Testing is easy. Pull the two vac connections off the vac motor, start engine in neutral (chuck wheels), plug the vac connectors one-by-one with your finger, in 2H you should feel the vac on one tube, then in 4h it should switch to the other. If ther is no vac then the hose is hosed (leak) somewhere, if there is vac but it doesn't switch then it's the vacuum switch on the tcase, if there is vac and it switches then it's the vac shift motor. Vacuum switch is a $20 part and easily replaced (it just screws right out, we needed a pipe wrench though). Motor is maybe $40, vac harness same. Let me know if you need more help.

'91 YJ, I-6, 3" lift, 31s
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post #3 of (permalink) Old 12-16-2000, 10:57 PM
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Re: axle disconect on YJ Dana 30

Depending on what year model jeep you have there will eather be two vacume hoses going to the shift motor and a wire or three vacume hoses. In my case mine is an 88 so there are three hoses. The one on the outside closes to the passanger side is the one that provides suction when in 2 wheel drive. The one in the middle supplies vaccume when in 4wheel drive and the other on goes to the switch that turns the 4wheel drive light on and you will never feel suction from it. It doesn't matter if you have it in 4wheel high or low you will still get suction on the middle one. Basically you need to pull off the one in the middle, put the transfer case in 4wheel drive and you should have suction. If not tell me and we will go from there.

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post #4 of (permalink) Old 12-18-2000, 08:31 AM
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Re: axle disconect on YJ Dana 30

Get the rocklock (cable disconnect) and you'll be happy
Never have to worry about it again.

89YJ-350V8,35" swampers,etc.
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