Figuring out a Dana 30 again -
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Unread 04-17-2010, 06:52 PM   #1
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1994 YJ Wrangler 
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Figuring out a Dana 30 again

I took out my front axle and I can't figure out what this thing on the axle is for. It had vacuum lines and electric hooked to it. Can you guys help?

dana-30.jpg   front-axle-dana-30.jpg  
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Unread 04-17-2010, 07:16 PM   #2
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That unit is called a "Vacuum Motor" and is used to engage your 4wd. The passengers side axle shaft is split and when it's disengaged, the axle "free wheels" but when the vacuum motor engages the 2 pieces, it causes the whole thing to work like a normal differentiated axle, so when the front drive shaft is engaged & the split shaft is engaged, you have 4wd.

There are quite a few threads here that show the vacuum "plumbing" that you need to have it work. There are also threads that describe how to make and/or install a manual shaft engagement system - called Posi-lock.
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Unread 04-17-2010, 11:50 PM   #3
Joe Dillard
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1991 YJ Wrangler 
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The system is called: central axle disconnect (CAD).
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Unread 04-18-2010, 08:38 AM   #4
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have fun replacing the intermediate seal. funnest job ive done yet. took me less time to remove rebuild add a sye and reinstall my transfer case
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Unread 04-18-2010, 09:10 AM   #5
runtime error = 0
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installed..... notice the fork up close in the picture, it goes over the collar you see in the dico box. the fork moves and locks the front axles together via vacuum lines when you shift the t-case into 4x4.

intermediate shaft, outter shaft, and collar all pulled out

the vacuum lines run to the t-case. it comes out on top of the NP231 right before it bolts to the tranny.

Originally Posted by ionakana
don't post threads that poke Poke!
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