just recently purchased a 1989 Cherokee pioneer and I need to know where the vacuum lines to the front locker come from and where they go to things of that nature for my front locker

 

Note from DJ
You decide keep or junk
88xj front 4 wheel vacuum help on 05-22-2015
https://www.cherokeeforum.com/f2/88-...m-help-210140/

 

Correct find on the link djg. Sierien..I think yo mean the "Disco". It's a vacuum controlled sleeve that disconnects the RF axle.

It's only purpose/function is to reduce wear on the front end components and what spins in the transfer case from the wheels. It's the lever for the Transfer case that engages the front drive-line. Myself and some other members prefer to have it work as Jeep designed it. I rarely use 4-WD and having that stuff spin lazy is fine with me. Or you can lock it in 100% of the time and not worry that when you select 4 wheel, it will be there. It's just a matter of wear vs reliability. The vacuum lines fall of easy. (I have a loose zip-tie holding mine on), also there were some bad castings of the fork in the disco which could have it brake. Your 88 might well have a "suspect" fork.

Sheez...Maybe Crusier will chime in.

 

It's purpose/function was to increase fuel economy and it failed miserably at that.

Chrysler ditched it in mid 1991.


The big issue is that the CAD system only fails when you need it the most.

Kinda like when you don't realize your wiper blades need replacing until it rains....

I know somebody’s system works and he advocates keeping it stock, but my exposure to the failures is probably hundreds of times greater than his, as a result of being Service Manager at a Jeep dealership from 1980 through 1992, and being a current XJ and MJ owner.

CAD stinks. Every Jeep I work on with it, I eliminate it. Guess what I find in the process? 25 year old busted vacuum lines, bloated vacuum line connectors, bad vacuum reservoirs and piping, bad transfer case vacuum switches. In other words, had the person gotten into a sticky situation and needed 4WD, they would have been screwed!!!

That's the tip of the iceberg. The factory went through 3 revisions of the shift fork also. The fork issue is non-existent if you just slide it over and leave it.

See the link below for complete instructions. Takes less than 1/2 hour.

https://www.cherokeeforum.com/f2/198...ss-91-a-38629/

 

There is one very good reason to keep CAD if you can maintain in reliable operating condition.

Let's you put an inexpensive lunchbox locker in your front axle with no downside.

 

http://www.offroaders.com/tech/Lunchbox-lockers.htm Agreed oldguy. I was wondering though, for highway use that having the spiders locked would sure spin the carriage allot.

.... Howdy Cruiser....
The fuel it does save is the energy spent spinning an bunch of stuff that doesn't need to. As long as fuel is cheap, and you don't mind buying and replacing parts unnecessarily, you are correct. (in my opinion).

 

Why didn't the models with the NP242 get better mileage then?

It was immeasurable and definitely not worth the added costs and failure rate of the CAD.......

That's the equivalent of thinking you'll get better mileage in your convertible if you shave your head instead of leaving your hair long........

 

Hey! You are finally getting it. Over two, or three hundred thousand miles you are gonna loose a bit of hair there. Hair grows back of course, but the chain in the case, the front drive-line a bunch of stuff there, carrier bearings, pinion ect, doesn't grow back. Why loose a hair or two every day while you have the top up?

My 90 with disco is just fine at 282K. My 90 with 242 at under 200K is on it's second T-Case, and it's not working right. (might be adjustment...

 

It's intended purpose Fuel mileage/Tire wear certainly aren't debates worth the time. However, it's value in terms of using a $300 locker instead of a $1,200 air locker certainly are. It's a 4 wheel drive and additional maintenance is to be expected on a sliding scale depending on the intended usage. Moreover, I don't believe the locker will cause any additional spinning of the carrier over the stock spiders when axle is disconnected on the highway or versus one with no disco and stock spiders. You can also upgrade the old disco axles to the larger 760 u-joints by using drivers side axle from any ABS XJ and pass side stub axle from a 95 YJ with ABS. A bud gave me the drivers side free and I bought pass stub for $180 new with the 760 joint installed and just knocked the tone ring off.

 

I totally agree about the debates.

But what about the internals of one of those lockers being spun all the time?

 

The carrier in the rear spins for every mile you drive right?

I expect the front should last just as long then which brings us back to the Fuel/Wear thing which we agree isn't worth it.

 

I don't mean to be snarky about it, just the way I feel about it regarding my own vehicle.
When putting an auto locker in the front axle you'll get a warning from PowerTrax and I suppose any of the others that they recommend an axle disconnect of some kind. The reason they give for this is and I quote "In case the locker gets a reference it doesn't understand". I know it's a safety issue but what exactly that quote means I'm not sure and I think I've got the mechanics of these lockers down pretty good. If you further research on the web you'll find descriptions of incidents where front locker owners with no axle disco wrecked their vehicles. The common theme seems to be going down hill on a turn and the locker engaged even though not accelerating causing the vehicle to go straight ahead no matter what you did.
You could always go air or e locker for $1,200 which essentially becomes the same thing as a disco axle with the same issue of moving parts but with the advantage of much stronger aftermarket axles. $$$

 

Got it, my mistake. At first glance I didn't get that it unlocks. With welded spiders, even with the disco disengaged I'm thinking the LF would spin things like crazy on the highway. On demand full lock, for the cost of some professional welding though! Maybe handy for a farm truck/Jeep or something...

I never mentioned mileage as a reason to keep the disco.

 

Really?

http://www.offroaders.com/tech/Lunchbox-lockers.htm Agreed oldguy. I was wondering though, for highway use that having the spiders locked would sure spin the carriage allot.

.... Howdy Cruiser....
The fuel it does save is the energy spent spinning an bunch of stuff that doesn't need to. As long as fuel is cheap, and you don't mind buying and replacing parts unnecessarily, you are correct. (in my opinion).
__________________

 

Yep, really. It's just the extra wear I don't like. If course it takes some amount of fuel to create that unnecessary friction and heat, but that can't amount to more than a few hundred gallons in 300K.