4x4 not working

my front wheels are not pulling the transfer case goes into low gear but front dont pull any help thanks

Could you be a little bit less specific?

Robert

ok ???

When asking for mechanical advice, it's always a good idea to list at least year, engine, tranny, and t-case.

For your problem, the engine and tranny aren't so important, but the year will tell us if you've got a solid axle or a vacuum disco, and since the problem is quite possibly/probably in the transfer case, you just might want to give us a heads up just what we're talking about...

Robert

Sharing information is an important first step in receiving answers to your questions.

Little bit of information like the year, engine, transmission, transfer case, any modifications that could be effecting things. You know, the simple things in life.

Pretend that there is no one standing there with you scratching their heads/butts. Pretend that all the people that might possibly help you can't see what you can see. Pretend that you have to tell others all about your vehicle and the problem you are experiencing.

ok sorry
it a 1989 xj laredo automatic
when I put in 4 wheel no lights come on and the front will not engage
What is a vacume disco
it is stock 4.0 220,000 miles
not sure about transfer case sorry

Well, if you've got 2H-4H-N-4L on your shifter, it's a 231.

Part time, full time, etc, is a 242.

An 89 with a 231 will have the vacuum disco, and that's probably your problem.

Robert

how does the vacume disco thing work

I did notice my brake booster has a leak could that be causing enough vacume leak to not engage front
thanks learning here

If you've got a 231, and a disco axle, the front right axleshaft is actually two separate pieces, an inner and an outer.


There's a small shaft that stick out the back of your transfer case.

When you shift into 4wd, that shaft moves out to trigger a vacuum switch.

That switch is connected (via vacuum lines) to a housing on the front axle, where the pass side control arms mount.

Inside the disco housing, there's a vacuum diaphragm attached to a shift fork. When it get the vacuum signal from the t-case, the diaphragm/shiftfork slide a collar that engages the splines on the two axleshafts, locking them together.

The same vacuum signal feeds an electrical switch, under your coolant bottle, that turns on the 4X4 light on the dash.

If the light isn't even coming on, you've likely got a pretty good vacuum leak somewhere...

Robert

<Edit, crosspost> Yes, You should definitely start be fixing any leaks you can find, and replacing as much 21 year-old vacuum line as you can.

There are those (okay, many) who will tell you the vacuum disco isn't worth fixing.

You can, in order of ease and expense (a) ditch the vacuum, shim the collar into the locked position with a bunch of washers, and forget it (b) ditch the vacuum, and install a cable actuated "posi-lock" or (c) ditch the disco altogether, and install a one-piece axleshaft from a 91-up XJ, or 96+ TJ.

With (c), you'll need to change an oil seal, but in upgrading the shafts, you can get the 297 ujoints (95+ or so) that are stronger than your 260s.

Robert

WrenchMonkey said:

There are those (okay, many) who will tell you the vacuum disco isn't worth fixing.

You can, in order of ease and expense (a) ditch the vacuum, shim the collar into the locked position with a bunch of washers, and forget it (b) ditch the vacuum, and install a cable actuated "posi-lock" or (c) ditch the disco altogether, and install a one-piece axleshaft from a 91-up XJ, or 96+ TJ.

With (c), you'll need to change an oil seal, but in upgrading the shafts, you can get the 297 ujoints (95+ or so) that are stronger than your 260s.

Robert

Click to expand...

I took my vacuum disconnect off, and took the c clip out, hammered the fork over, and then reinstalled the C clip, that way it always stays locked in place, sort of like having a np242. All it does is make your axle basically solid like that of a 91 (i think thats the year) Either way, its an easier fix, and you don't have to worry about that vacuum mess. Mine failed out on the trails, and that was the last time i let it happen. Then i ended up swapping a t-case out of a 96, that didn't have the vacuum switch anyway, so it all worked out for the better.

WrenchMonkey said:

(b) ditch the vacuum, and install a cable actuated "posi-lock"

Click to expand...

This gets my vote.
I'll see if I can find the write up on a home made one and post it.
LOTS cheeper that the "actual" Posi-Lock cable.
You will be able to have 2 wheel drive LOW also with this mod.




EDIT:
Not the same one I was thinking of, but here ya go........
http://www.jeepforum.com/forum/f12/home-made-posi-lock-write-up-595515/

Here are the benefits of this mod......

4x4 Posi-Lok reduces front differential wear and right axle breakage.

4x4 Posi-Lok provides 2-wheel drive low range, giving the vehicle 4-LO torque at the rear axle with bind free steering only available in 2-HI. This feature is not available with factory systems and is beneficial when maneuvering trailers.

4x4 Posi-Lok will not disengage when ignition is turned off or the differential is submerged.

4x4 Posi-Lok is compatible with manual or electric transfer cases and installation can be completed in one to two hours with basic hand tools. No internal differential work is required.

JPMagazine's take on the D30 CAD axle:

http://www.jpmagazine.com/techartic...154_0904_dana_30_vacume_disconnect/index.html

Yep, pretty much what I said. They bolted the collar instead of just shimming it, but the same effect...

For what it's worth, I'm still running my vacuum disco, after 200,044 hard miles.

I ran new vacuum lines to a manual air switch under the dash, so I can engage/disengage that axle shaft whenever I want.

This lets me control my $200 lockright just like an $800 ARB selectable.

And I did upgrade to axleshafts from a 95 YJ, which is the only way to get the 297 joints and keep the disco.

I myself have had almost no problems at all with this setup. The first trip out after I installed my drop brackets, the front axle drooped so much farther than I expected that it actually unplugged the vacuum lines from the axle. I repositioned the lines, and it's been good as gold since.

I understand that I'm the minority opinion on this, but there it is...

Robert