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Front end vacume lock

M

mg1234

NAXJA Forum User
Location
California
Just got an 88 XJ and want to change the vacume actuated locking mech on the front diff with a mechanicle one ,don't know anything about it just heard about it can you guys give me the name if the kit and where I can get one ? It seams like the small vacume line could easily break or tear and leave you stuck ,true?
 
I think this is like a choke cable that pulls the lever instead of the vacume ,don't know how any of it works ,been in off road for 35 years but my 1st jeep ,
 
If you don't wanna change shafts, just lock it over permanently. Takes about 1/2 hour, no parts to buy, run it.

Search - CAD delete. You'll find several good write-ups.
 
4x4 posi lok is the product you're thinking of
 
I like my posi lock cable but its pretty stiff and I have to jiggle it and goose the gas to get it engaged sometimes. The cable I bought seems way too long, I think if it was much shorter it would work much better. Where do you get one of these solid axles?
 
you've got small u joints anyhow, so just find a later model D30 in a yard and swap it.

You'll ditch the vacuum stuff and get stronger shafts out of the deal.
If your knuckles/brakes/bearings are in good shape you can just swap them to the new housing.
 
ParadiseXJ said:
If you don't wanna change shafts, just lock it over permanently. Takes about 1/2 hour, no parts to buy, run it.

Search - CAD delete. You'll find several good write-ups.
Click to expand...

X2. just open up the actuator push the lock collar over into the lock position and throw some zip ties around the axle to keep the collar from unlocking. there is no side load on the collar, so it will stay in place without much effort. remove the fork and you are good to go. You won't notice any difference on the street. I ran it like this for a couple years, then swapped to a 1 piece axle.
 
mg1234 said:
It seams like the small vacume line could easily break or tear and leave you stuck ,true?
Click to expand...

No, not at all.

Most of the issues with the vacuum disconnect were with the ""motor"" failing entirely and either preventing lock or unlock, and occasionally a fork would break.

The ""Motor"" is just a diaphragm attached to an fork. Move it one way, and it slips a collar over the shafts locking them together, slide it the other, and it slides it to the inside shaft. The vacuum is regulated by a vacuum switch on the Transfer-Case. Vacuum on one side of the actuator, and the fork slides one way. Vacuum on the other and the fork slides that way. Easy-Peasy.

An '88 with 260 shafts and no front locker should be OK esp with Stock up to 31" tires. Heck, I had a YJ with 260 shafts and 33X12.50s with zero breakage. It's all in how you approach things and driving style.

Cable kit:
http://www.4wheelparts.com/Drivetra...pcfon=1&gp=1&gclid=CPXxg9j6mcICFWFgMgodyyEAKQ

What's involved in replacing the shafts:
http://www.jeep4x4center.com/pdf/ALL-12131.pdf

HTH: ~Ron
 
Failure won't leave you too stuck, just without 4WD. While it's true the vacuum motor is a usual failure point, I will mention that on my 87 absolutely everything that could fail did at least once. The vacuum motor (2 of them), the rubber harness to it (cracked), the metal vacuum lines (rust pinhole) the vacuum line under the battery, the vacuum bottle (a double bottle on the 87, so all the stuff on the unbroken side worked), and the vacuum switch on the transfer case. Never at the same time, of course. Cable ties or a stack of washers will save you a lot of diagnostic time if nothing else.
 
Matthew Currie said:
Failure won't leave you too stuck, just without 4WD. While it's true the vacuum motor is a usual failure point, I will mention that on my 87 absolutely everything that could fail did at least once. The vacuum motor (2 of them), the rubber harness to it (cracked), the metal vacuum lines (rust pinhole) the vacuum line under the battery, the vacuum bottle (a double bottle on the 87, so all the stuff on the unbroken side worked), and the vacuum switch on the transfer case. Never at the same time, of course. Cable ties or a stack of washers will save you a lot of diagnostic time if nothing else.
Click to expand...

I couldn't agree more.

But you left out the 2 versions of shift forks that bent also!!

Take half an hour and do the fix:

http://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/
 
Matthew Currie said:
It's true, my shift forks never bent. I don't think the system worked long enough at a time to bend them.
Click to expand...

Probably so!!

I was at the dealership when these were new.

First off, the vacuum harness either fell off or got soaked from oil when changing the filter.

A few vacuum servos also failed.

The earliest shift forks bent.
The next generation were stronger but caused the slider to travel too far and "stick" on the axle splines and not allow engagement.

Sometimes the vacuum switch on the transfer case failed.

I don't know about you guys, but when I go out 4 wheeling, I expect to 4 wheel.........
 
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