vacuum axle

so..i have a problem...i recently swapped a 1994 4.0L ax-15, np231, into my 1989 PREVIOUSLY a 4.0l aw4, np231...my problem is that the axle on the 94 jeep that i got the drivetrain from was not a vacuum axle and my 89 is...so...considering the fact that i had to use the t-case from the 94...how will i make my front hubs engage? is it possible to take the vacuum valve out of the 89 t-case..and hook it into the existing vacuum lines in the 89 engine bay and then just run it into the cab and when i want to lock the front end in i just push in the button on the valve...i ask this b/c that is all the t-case appears to do to this mechanism...when you put it into 4wd the rod comes out and pushes on the ball thing to open the valve....and the 94 t-case doesnt have the same rod thing to push on the valve..b/c the 94 wasn't a vacuum axle jeep...so can i do this just by hand or am i guna have problems..PS i do NOT want to pay some 200 dollars for a cable lock thing...any help appreciated!

here is a link on how to make one of the manuel disconects for about $20.
http://home.earthlink.net/~stevenschreiber/jeep/tech/cabledis.htm

Even easier, get a one piece shaft, a 11771 Seal (National Seal#) or a 40576S (Chicago Rawhide #) and eliminate the two-piece axle altogether. You can leave the vacuum actuator on or instal a blank plate with some RTV for a gasket.

Easiest, and cheapest (like I like my wimmins) is this:

Open the vacuum control box, slide the collar to engage the splines, shim it with some washers to keep it in place, and button it back up. Don't forget to cap the vacuum lines...

Robert

yup thats what I did on mine,shimmed it over with washers.But I'm actually going to make the homemade posi lock that was mentioned above.That way I can run a front locker on the street and then when on the trail I can shift the axle to lock...

hey one2rce...do you think instead of using a spring on the fork..i could just use like a push pull cable...like a manual choke cable for a tractor...b/c when you pull obviously the choke opens but to shut it it doesnt use a spring...you just push the cable...it goes both ways...would this work for the axle disconnect fork thing?? thanks!

89HEEP said:

...do you think instead of using a spring on the fork..i could just use like a push pull cable...

Click to expand...

Of course. That's what most people do. One-2's link uses the spring, apparently, to hold the axle on the locked position, and open it only when you pull the cable. Sounds like a hassle to me, since you'll be wanting to "unlock" it when you're turning tight, and your hands are busy...

What "I" did was install an air valve in the cab, and ran the vacuum lines to it instead of the tcase. Works great for me, wasn't too hard to hook up, and since I got a 5-way air valve outta the trash at work, it was nearly free.

But if you don't need to disco the axle, the washer-shim method is still the easiest and cheapest.

Robert

ColoradoJeepXJ said:

Why deal with more vacuum issues. Go with the one piece shaft or do what I did and install a manual axle lock.

Click to expand...

Well, mine was sort of a challenge to see if I could create something new out of what someone else considered garbage. And I did, and it works like a charm...

But a one piece is (a) a lot of money and (b) non-selectable.

And the posilock is $225... way too much for what I did for free...

Robert

robert771, can i just use the valve thing that orig went into the t-case...? b/c like i said in the begining of the post...i have a 94 t-case now...so the vacuum lines that come up from the axle and then into the engine bay, then go back to the t-case...cant go back to the t-case ne more...so instead of going to the t-case cant i just run that valve into the cab and then press it in when i want the vacuum to lock...isn't that an air valve?

?does ne one know? otherwise robert771...can you maybe take a pic of what u've got goin on?thanks anybody

Well, first, Colorado is right. The vacuum actuator is a less-than-ideal design. Mine happened to be working well, and I happened to get my hands on a salvageable air valve for nothing. I would have thought at least twice before spending much money on the vacuum setup.

Without pulling my kickpanel back out, there's really nothing to take a picture of, just a little lever with a black knob, sticking out where my hood release should be. I'll search later for a pic of the type air valve I used.

Second, Frank Z is also right. If you don't really need it to be selectable, the one-piece axle is logically going to be stronger. DO you need it to be selectable? Unless you're running an auto locker (like my lockright) or expect to one day, you really don't need the disco. Then the cheap way is the washer-shims, the stronger way is the one-piece axle.

If you decide you do want the disco, I'd suggest a DIY job like one-2 linked to. I just don't see the posilock being worth that much money (but lots of folks have em and say they love em...)

So I guess... I'm agreeing with everybody, huh?

Good luck,
Robert

Well, this is a three way, rather than the five way I used, but you get the idea...



That one's $46 at MSC Direct

Robert

well...i guess what i really didnt understand was how you knew what vacuum lines did what and how to hook them to an air valve..are there even 5 lines to hook up? i only ask b/c u said you had a 5 way air valve..do i need a 5 way air valve? sry i guess im just kinda confused lol.

89HEEP said:

well...i guess what i really didnt understand was how you knew what vacuum lines did what and how to hook them to an air valve..are there even 5 lines to hook up? i only ask b/c u said you had a 5 way air valve..do i need a 5 way air valve? sry i guess im just kinda confused lol.

Click to expand...

Okay, first, I have to assume that you read everything I said three posts back, and for your own reasons (or curiosity) you want to know more about my setup...

A three-way valve may work, depending on how it's set up. There's a diaphragm in the actuator. You apply vacuum to one side to engage, the other side to disengage. But you also need to release the vacuum on the opposite side.

I'll try to explain using the hoses you've got. The red hose is vacuum supplied from the canister behind your bumper to the switch.

The switch (either on your tcase or under my dash) applies that vacuum to the yellow hose to engage the axle, or the green to open it up.

At the same time, that switch connects the opposite line (green for yellow, yellow for green) to the blue vent hose, to release the vacuum on the backside of the diaphragm, basically letting a little bit of air in.

I did away with the vent hose, and just put little filters (1/4" mufflers, actually) on the valve body under the dash. When my five-way switches to the yellow, it connects the green to that fifth outlet, and vents it.

A three-way may be set up internally to do that automatically: Connect A to B and vent C, connect B to C and vent A. You'd be good to go.

OR, it might connect A to B, and deadhead C. In which case, you'd still have vacuum "stuck" on C, and thus on both sides of your diaphragm. And nothing happens.

This sounds complicated explaining it here, but it's really not. I've never seen anybody else doing it, though, and you might wanna ask yourself why...

Hope this helped, anyway, ask back if not...

Robert

i think i know what your saying now...that did help make more sense of it all....thanks i appreciate it...maybe i'll update later on whatever i decide to do w/it.

well..all i did was run the old vacuum lines that used to go to the t-case..into my cab..since ihave a dif t-case now...and i simply/ have to flip a lever that presses the ball on the valve in and that lets the vacuum go to the axle..or w/e it does..and locks my axle...it works exactly the same as it did stock cept for i have to run the vacuum valve manually from in the cab instead of the t-case running it w/the shaft that pops out when u shift it into 4...thanks for ur help robert771, it helped me figure out why i had no vacuum haha....thanks again.