84' NP229 to NP208 swap....what about the Vac disconnect axle???

[billyrb]

Ok, so I have made the financial decision to swap over from the current NP229 to a part-time NP208. But, the problem I have is that my jeep has the vacuum disconnect D44. My questions are this:

1. If I remove the vacuum actuated NP229, what do I do with the vacuum lines that went to it? I have seen in the routing plans that the vacuum first goes to the axle, then to the xfer case. When you change out of 4wd, it goes opposite.
2. Can I just re-route the lines so that they only go from the switch to the axle and back to the switch?
3. If not, can I just remove the existing axle shafts & disconnect hardware, and swap in regular axle shafts? If so, which shafts should I use? (btw, I don't want to change the entire axle, if possible)
4. If I do swap in different axle shafts, then will I have to install locking hubs? Call me lazy, but I really don't want to get in and out of the jeep every time I want 4wd.....

What are my options?

[joe]

I would go with 2. rather than 3.
I don't know if the left axle from a conventional axle will be a direct swap? Then if you want to get rid of the vac motor on the axle I think the mounting surface for the cover is a different shape than on a non-vac D44 so you may have trouble finding a plain cover. Not real sure on the above but I remember folks having trouble finding gaskets for the vac-cover because they weren't the same. Something worth checking into anyway before you start tearing things apart or buying parts.
The vac axle is pretty reliable "if used occasionally". What seems to cause problems is if the vac motor isn't used very often it tends to freeze up. The ones used regularly are pretty trouble free.

[billyrb]

So I can just remove the xfer case vacuum diaphragm, and just re-route the lines so they only go from the switch to the axle & back? I would rather leave the axle shafts as is, as I don't need the extra work right now.

[dnixon]

I actually just did this.. Re-route the vac lines that is. I swapped to the NP208 and kept my Vac Axle. Joe has a really good diagram that shows you exactly what lines get vaccum during 2wd operation and 4wd operation. But if you want I can go take a gander at mine when I get home and tell you exactly what lines to plug and what lines to connect to each other for the ones that went into the NP229.
The kind of neat thing about this is that you can run in 2Lo if you keep the front disconnected and then put the 208 in Lo. and also I hear its MUCH easier to steer if you have a locker up front without the vaccum hub engauged. So thats kind of a bonus thing too...
I think Scotty really digs the vac axles he has said that he swapped one into his XJ and has on in his FSJ i think.. says he beats them up pretty good and the vaccum hum hasn't broken. So he only has good words to say about them. Just FYI...

[billyrb]

I've heard good things about the vac disco axle, but wasn't sure how it would work with an NP208. Now that I know I can keep the Vac disco, I'll just re-route the lines and go that route.

Joe, can you email those diagrams to me at ryan@bjsoffroad.com? Thanks!

Donovan, can you also email me what you did? Thanks!

[joe]

Originally posted by billyrb:
Joe, can you email those diagrams to me at ryan@bjsoffroad.com? Thanks!No problem Ryan.

[FrankenJeep]

FWIW, I'm running an NP229 to NP208 swap with no problems to report. The switch operates the front axles only, and the only thing you need to watch is to periodically check the vacuum switch for leaks. If it leaks, its easy to pull apart and add a little grease to reseal the unit.

[Horny Toad]

Would one of you mind sending me that vac line diagrams to cdwentland@cdwpls.com

Thanks,

HT

[scotty]

i do dig the disco axles :cool: i have the currnet axle in my xj hooked to its own switch and am in the process of building a d30 with lockouts and a disco. im planning on lincoln locking the front. ill be able to unlock the lockouts if i dont want anyting to spin,and with the hubs locked ill be able to disconnect the right frotn with a flip of the switch

im running a plain old WT 44 with a pass side drop in my GW. i would swap a disco axle in a heartbeat if i could find one with a pass side drop :mad: ive heard dodges use a disco pass side diff axle in certain years,but i have not been able to find one.

definatly hook the switch up like the guys said so you caN control the front axle seperate from the transfer case.if i were ever to swap in a driver side diff again,id swap the disco axle up front. the disco axles are cool smile.gif

[Subconscious]

I'm in the process of getting an NP208 to swap into my '87 Grand. Do I have a vacuum disconnect front axle also? I thought I had automatic hubs (?). I was hoping to ditch the switch...

[joe]

Nope, only 83 and 84's w/229 had the vac axle. Oh and you're hubs aren't automatic. They're just conventional locked all the time hubs. If you want them to unlock you'll have to install unlocking hubs.

[jc turtle]

HI, i must disagree about auto hubs not unlocking. there is a multi sided hub that is connected to the axle, on the outside, there is a round hub that is connected to the rotor and hub. between the 2, there are cylindrical pins that roll in the space between the outer and inner hub, when power is supplied, the pins are forced to the outer edge of the inner and outer hubs, locking them together. when there is no power, the rollers allow the outer hub to rotate, free of the outer hub. thus free wheeling hubs. john

[joe]

There is such a thing as automatic hubs on other vehicles but not on FSJ's.

[scotty]

people typically call a "drive flange" an "auto hub",or "permantly locked hub"

technically speaking,the "hub" is the piece that houses the wheel berings and the rotor is attached to. a "lockout" or a "drive flange" is used to transfer the spnning motion of the axleshaft to the hub

a drive flage is "permantly locked" and is simply a piece of metal splined to fit the hub on its outside diameter and the axleshaft on its inside diameter. this is what all FSJs equipped with a full time t case came with(borg-warner QT,np 219,228 or 229)

the above post from mr turtle is a good description of an automatic-locking lockout that came on some mid-late 80s chebbies,among some other things.

[ July 26, 2003, 05:58 AM: Message edited by: scotty ]

[Mxlt]

If replacing the NP229 with a NP208 in a '87 GW Stock form, I know the rear shaft has to be longer but does anybody knows what's the right length of the replacement shaft?. What about the fornt one?. Does it have to be replaced too?. Also, how would the operation of regular onroad/offroad driving has to be when having this setup?.

[Kris]

Originally posted by Mxlt:
If replacing the NP229 with a NP208 in a '87 GW Stock form, I know the rear shaft has to be longer but does anybody knows what's the right length of the replacement shaft?. What about the fornt one?. Does it have to be replaced too?. Also, how would the operation of regular onroad/offroad driving has to be when having this setup?.The rear needs to be lengthened "about" 5 inches but it is best to measure the running length installed in your wagon, then let the driveshaft shop determine the proper length.
The front will be fine as is.
You will not be able to use 4hi on dry pavement as there is no diferentation between front and rear outputs in the 208. 4lo will be the same with both cases.
kris.

[Mxlt]

Thanks Kris, pretty clear now. Would I have to do anything to the front shaft if I decide to have a suspension lift kit on the GW eventually?. Thanks in advance.

[Kris]

Depends how high you go.
If you are doing 4" or less, probably not.
The front case half of both cases are dimentionaly the same, the front output sits in the same place. On the 228/229 cases the dif/viscous units are in the back half. That is why the 208 is shorter.
kris.

[Dive 30]

For the rear shaft grab one from an 80's (post quadratrac) J-10 or from a Quadratrac wag, this is a direct replacement and much less expensive than a new or lengthened shaft.

Phil

[todd8]

I know this is a long time after the origional discussion, but what I did with my 84GW was, removed the front cover of the axle, removed the vacuum shift motor, and replaced it with a threaded stud and nuts, basically locking the collar in permanantly, and installed manual locking hubs. I had planned on running this untill something broke, then swapping in a standard d-44 axle I have. But, 2 years later, the thing is still going strong, and I dont have to worry about tearing out vacuum hoses back in the stix.
Todd 84 85 GW 68 J-2000

[billyrb]

I still prefer the re-routing of the vacuum. Wheeled mine for a year and change in lots of places, never once had an issue with anything being ripped off.

[Jeepjohnny]

Sorry to reposted in a reposted older thread. But the Vacuum diagram you guys were refering to in this thread... Can any one dig that up... I'm sure I could figure it out for myself.... but shoot, if its already been figured out there's no since reinventing the wheel.

Jeepjohnny@yahoo.com


Thanks!

:fsj:

[Mark Wilde]

Thanks Kris, pretty clear now. Would I have to do anything to the front shaft if I decide to have a suspension lift kit on the GW eventually?. Thanks in advance.

I'm currently runnning a 4" all-spring Rusty's lift, with no mods on either shaft. Works well; I have run good trails with it with no issues (nothing extreme.):eek:

Echo on the rear QT shaft; I measured a stock 208 shaft and a QT shaft at the junkyard once, the QT shaft is about 1/4" longer than the stock 208 shaft. Would work perfectly with a lift.:thumbsup: :fsj: