Hey guys...I am new and need help. I have a 92 cherokee that the front end is shot. I bought a rolled 90 to use some of the parts. The problem is the 90 has a front vaccum operated locker and mine does not. anyone know how to hook up the system because the motors are a little different and a do not see an electrical connection for the Mechanism that the vaccum lines go into on the passenger side.. any help would be awesome...

Thanks

 

Usually people go the other way, swapping the solid axle in for the crappy vacuum actuated one. The easiest way to eliminate the vaccum thingy would be to tack weld the actuator in the engaged position. What's wrong with the front axle you have? IMHO, I'd probably fix it instead.

 

The mounts on the axle torn from abuse and the 3rd member is making noise. wait the vaccum thing is better because it is a locker when the one i have is a standard open diff with no locke rright? if i tack weld in in the engaged position it will not steer right on the street right?

 

Ok you have a front axle vacuum disconnect system on you new axle not a locker, this thing is a liabilty on the trail and from what I've found is prone to failure, mine did. It what makes your front wheel spin when your in four wheel drive. It's not a locker, if this thing isnt working you wont have and power going to the front tires.

 

How is that? There is till a drive shaft turning, when I unbolted the unit from the axle it was nothing more than a coupling that when engaged tied both axles togther like a spool so they both pulled....

 

front is an open diff, so the diff thinks the passenger side wheel has no traction, so the diff sends all the power to that wheel with no engagement. it is not a locker. it is a two piece shaft with a lock collar to engage both pieces as it is one.

i would just get another axle, without the vac disconnect. also, the vac axle has the smaller, undesired 260 u-joints as opposed to the larger 297 joints.

 

Okay if it is an open diff what is the point of the coupling... am comfused

 

It acts like unlocking the hubs on a rig with unlocking hubs. When the axle slider dealy is uncoupled the front drive shaft does not turn while driving. It's kinda a crappy set up. Mine failed, hence the tack weld. Another thing, I'm going to guess you have the NP 242 Select-Trac t-case. If you put the part time front axle in your rig the you auto 4x4 won't work anymore. Now if you are really hard pressed and need to put the vacuum axle in, weld or disable the accuator in the engaged position and call it good enough. It'd be a wasted of time to install the vacuum system IMHO. They do sell cable kits as well: http://www.4x4posi-lok.com/app_jeep.html

 

okay this is starting to make sense...... As far as the T-case i have 2. I have my stock 92 one, as well as the one out of the 90 which has the vac lines on the tail of the case. Can i run my 92 t case on the 90 axle and weld the coupling in the Coupled position? If i do this will it operate properly on and off road in 4 and 2 wheel drive?

 

Ok, lets make sense out of all of this. This a breakdown of the axle options for each year.

Axles

Front Axles


Dana 30 high pinion - reverse cut - 27 spline, 1.16" diameter shafts, 7.13" ring gear - used 84-99 (some axles through 91 are vacuum disconnect, 92+ are non-disconnect, 89-95 with ABS have 5-297x u-joints, all 95+ have 5-297x u-joints, all others have 5-260x u-joints)



Dana 30 low pinion - standard cut - 27 spline, 1.16" diameter shafts, 7.13" ring gear, 5-297x u-joints - used 00-01


Rear Axles


Dana 35 non c-clip - 27 spline, 1.18" diameter shafts, 7.58" ring gear, 2.62" axle tube - used 84-89

Dana 35 c-clip - 27 spline, 1.18" diameter shafts, 7.58" ring gear, 2.62" axle tube - used 90-01

Chrysler 8.25 - 27 spline, 1.17" diameter shafts, 8.25" ring gear, 3" axle tube - used 91-96

Chrysler 8.25 - 29 spline, 1.21" diameter shafts, 8.25" ring gear, 3" axle tube - used 97-01

Dana 44 non c-clip - 30 spline, 1.31" diameter shafts, 8.5" ring gear, 2.75" axle tube - used 87-89 on some (not all) XJs equipped with towing package.


Note: Dana 35 axles sometimes referred to as Dana 35C - The "C" does not stand for c-clip. It stands for "custom" meaning it came from Dana unfinished.


Note: 8.25 axles - none of these axles were used on XJ's with ABS brakes. If you have ABS, you have the Dana 35. Without ABS you could have either axle. 8.25 axles are c-clip.


Now, the vac disco actuator is not a locker and does not act like a locker. The hubs on the XJ do not lock or unlock, they are simply a sealed unit bearing and that is all. All of the 4wd shifting and engaging functions are handled within the tcase and not in the diff.

The vac disco actuator has only one function, to connect the 2 pieces of the passenger side axle shaft. Locking the actuator in place to permanently connect the 2 pieces is absolutely no different than having the non disco axle with the 1 piece shaft.

The front driveshaft always turns no matter if you are in 2wd or 4wd, with or without the vac disco axle. It always turns and it is normal.

 

Now, the vac disco actuator is not a locker and does not act like a locker. The hubs on the XJ do not lock or unlock, they are simply a sealed unit bearing and that is all. All of the 4wd shifting and engaging functions are handled within the tcase and not in the diff.

The vac disco actuator has only one function, to connect the 2 pieces of the passenger side axle shaft. Locking the actuator in place to permanently connect the 2 pieces is absolutely no different than having the non disco axle with the 1 piece shaft.

The front driveshaft always turns no matter if you are in 2wd or 4wd, with or without the vac disco axle. It always turns and it is normal.[/QUOTE]




Okay man thanks.... But if the front drive shaft always turns how is it not in four wheel drive? What is the difference in the t-case with the vac and without....

 

The axle is turned by the differential at the same rate as the t-case, even when the t-case is not engaged. This allows you to be able to switch between 2H and 4H while the vehicle is moving.

 

Well thanks so far for all of the help.. From what i understand i can weld the coupling in the coupled position and it will not affect the drive and it will be like all of the later model front axles right?




But what about the t-case... should i use the non vac t case?

 

use what you got in already, no need to change out cases.

if you're gonna use that vac disco axle, just permanently lock it in and go.
if you're using tires larger than 31s, bring spare shafts and u-joints if you wheel it. you might be fine with 33s, but be ware. those are small and weak u-joints. don't jump it, and definitely don't put a locker in it.

 

[QUOTE=caged;457444]use what you got in already, no need to change out cases.

Okay thanks for all of the help. I do still have some questions.. If the front shaft is always turning is it not in four wheel drive all of the time?