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Topic Review (Newest First)
03-22-2012 01:48 PM
Originally Posted by Escobarclan View Post
So let me get this right guys...

When the transfer case is in 4wd, the drive shaft gets power. It will only power one side of the front end, and the vacuum system locks both sides together, right?
Well when you shift into 4x4, the shift motor will engage both sides of the axle, so you should see equal power to both sides of the front axle.
03-22-2012 01:16 PM
tchoberg Scroll down in the thread and there is the 4x4 vacuum diagram. I used this diagram to figure out what does what and to fix the 4x4 vacuum mine on my '87 YJ. My problem was a broken line right at a fitting and was solved by a short piece of 1/8" wiper hose to couple things back together. Good luck.
03-22-2012 12:43 PM
Escobarclan So let me get this right guys...

When the transfer case is in 4wd, the drive shaft gets power. It will only power one side of the front end, and the vacuum system locks both sides together, right?
03-20-2012 08:07 AM
Master4th I did this mod and removed all those crappy vacuum lines.
03-20-2012 07:53 AM
kik Like 4Jeepn said, it enables 4wd through vacuum. If it's working you'll be in 4wd which as you know is easy to determine. If you are, meaning it's working, I would leave it alone. Just had to replace the vacuum actuator on my 89 the other day.
03-20-2012 07:34 AM
4Jeepn The YJ system has a shift fork on the right side axle tube.. the vacuum pressure when put into 4wd will make the shift fork slide over a collar between the inner and outer axle shaft on the passenger side, thus "locking" them together. yes the YJ does not have solid axle shaft on that side. the theory was it would help with mpg's, with less rolling force or something like that. With age any number of things can go wrong with it. Most folks will pin the folk in place or swap in a 1pc axle shaft out of xj or tj, but you need to add a different inner axle seal when you do that.
03-20-2012 05:12 AM
Front axle vacuum locker system info

Hey guys. Now that I'm almost done getting all the engine bugs out, I'm beginning to wrap my head around the vacuum lines going to the front axle.

Here's my question: I understand that the transfer case has a mechanism by which going into 4hi or 4lo will engage the axle locker. Being an old cj'er, what does the locker do? Is it an axle locker that locks in both hubs, or a locker for the drive shaft to engage to the front drive system.

Tomorrow I'm going to test the 4wd, if by some chance (highly likely with my luck) the 4wd is working, is there a way to tell the difference between a working and non working vacuum system?

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