Dana 30 vacuum disconnect axle to a 1 piece axle! Im confused, help - Jeep Wrangler Forum

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Old 08-08-2014, 06:49 PM   #1
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Dana 30 vacuum disconnect axle to a 1 piece axle! Im confused, help

I am taking apart a dana 30 that has the 4.10 gear ratio that I need. I plan on replacing most components while they are easy to get to. I am confused by the 2 piece disconnect/vacuum axle.... What is the point of this?? Doesn't the 4wd engage in the transfer case? What does that little locking gear in the vacuum do? I've seen some conversions to a 1 piece axle and replacing the vacuum with a block off plate, there seems like there has be more to this conversion. Do you just install the 1 piece axle shaft and the lockoff plate and drive away?? Is there anything else required of this mod? Thanks
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Old 08-08-2014, 07:39 PM   #2
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the disconnect axle was a misguided attempt to improve fuel economy

the transfer case only engages the front driveshaft
if you have an open diff in the front, power would go to the side with the least resistance - the unlocked side

you do need to add 2 more oil seals when going to a one-piece axle

it you get vibration afterward, you may need get the front driveshaft balanced

http://www.stu-offroad.com/axle/yjd3...jconvert-1.htm

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Old 08-08-2014, 09:50 PM   #3
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Yea that's what I thought! What did that save in mpgs? A hundredth of a mile? Ha, i plan on changing out all the seals anyway so I may as well upgrade to the stronger ujoints and 1 piece axle while I'm at it!! Do the seals at the vacuum stay in place or should they just be removed?? Thanks for clearing this up! Any benefit in keeping the vacuum disconnect style?? I'm pretty much in 4 high all winter due to constant snow and ice and have not noticed any vibration so hopefully ill be good
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Old 08-09-2014, 07:27 AM   #4
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Put in the one piece shaft and don't look back - there is no downside. It's great that you are doing it now, while you have everything disassembled.

To clarify, you only need to add one seal to the passenger side, not two as stated above. That seal (napa 11800) will go next to the carrier in the end of the tube.

I like to buy a couple of each seal, in case I mess one up during installation (which is easy to do). You can return the extras if you are lucky with the first seal.
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Old 08-09-2014, 01:03 PM   #5
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X2 on what stanf said. The other reason to have a disconnect axle was to reduce transfer case wear, old gear driven transfer cases couldn't take the front driveshaft spinning all the time because of tight tolerances within the gears. That's why most older 4x4's had locking hubs as well. Jeep thought the same thing when they switched to chain driven transfer cases, but the chain could have easily withstood the front shaft constantly spinning.
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Old 08-09-2014, 06:51 PM   #6
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So as far as the seals.... There seems to be conflicting info out there. Should there be 1 at the pumpkin and 1 at the outside of the vacuum?? Or just 1 at the pumpkin and none at the former disconnect housing? Thanks
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Old 08-09-2014, 07:29 PM   #7
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Quote:
Originally Posted by beardown View Post
So as far as the seals.... There seems to be conflicting info out there. Should there be 1 at the pumpkin and 1 at the outside of the vacuum?? Or just 1 at the pumpkin and none at the former disconnect housing? Thanks
Just the Napa seal number stanf gave that will go in the housing. None at the old disconnect
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Old 08-09-2014, 07:57 PM   #8
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Do you know if its the same seal for both the driver and passenger side? I'd think they'd be the same but that almost seems too easy
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Old 08-09-2014, 08:36 PM   #9
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I like that CAD stuff.
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Old 08-09-2014, 08:37 PM   #10
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Quote:
Originally Posted by bad impulse View Post
Do you know if its the same seal for both the driver and passenger side? I'd think they'd be the same but that almost seems too easy
Different seals - the driver is per the parts store lookup. Napa 11800 on the passenger side
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Old 08-09-2014, 08:38 PM   #11
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That's what I figured,,, seems overkill for another seal to be at the disconnect housing that some writeups say.... Thanks,
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Old 08-09-2014, 08:48 PM   #12
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Quote:
Originally Posted by StanF View Post

Different seals - the driver is per the parts store lookup. Napa 11800 on the passenger side
Thank you.

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