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View Full Version : Front wheels don't spin in 4x4?


Dude13450
03-22-2013, 01:17 AM
I want to try my 4WD, so I put it into 4HI, and floored it in the rock lot next to my house, but only the rear wheels spun when I floored it (I could hear them slipping, but looked at the front wheels, they were only moving as fast as the car was, the rear would just "burnout").

I looked at my dash, the 4x4 light DOES come on, any ideas? I'm going to try 4LO tomorrow, but this has got me concerned.

Mine's an '87 Cherokee Laredo 4.0L I6 4x4 4dr.
XJ Wheeler
03-22-2013, 01:24 AM
No worries, bud. You're '87 has a disconnect front axle. Basically it uses vacuum to lock together a two piece axle shaft in the front axle (passengers side). They did this so the front axle wouldn't turn while on road to help mpgs. Most likely its just a vacuum leak. There should be three lines going to the CAD on the passenger side front axle (toward the rear). Two control the fork that locks the shaft, and one for the light. Just look for cracks/leaks. The line is cheap and easy to replace if you don't feel like looking. Wouldn't hurt either way.
Metlic53
03-22-2013, 01:29 AM
Yup, the CAD isn't engaging the axles.
you could fix the vacuum leak or buy this so you could use 4LO in just 2wd, its fun for doing donuts on dirt...if your rear is locked.

http://www.quadratec.com/products/52435_0X_PG.htm
Dude13450
03-25-2013, 07:06 PM
I think I might have just found the culprit:

http://i1057.photobucket.com/albums/t384/1986Civie/WP_000180_zps4293c191.jpg

But where exactly is the line that it attaches too? I found it like this directly below the coolant overflow reservoir.
4.3LXJ
03-26-2013, 12:07 AM
You have one that goes directly to the vacuum switch on the tcase. It is probably laying around somewhere
Dude13450
03-26-2013, 01:58 PM
The blue line is just a vent line. If you plug that line, the 4WD won't engage properly. The black disc is a check-valve/filter, which may need replacing.

I have been noticing that my truck feels different when letting off the brakes (in drive) engaged in 4L, which is why I think just need a new filter - its "engaging", but the front wheels don't spin when I floor it in rocks/dirt.
89Laredo
03-26-2013, 02:41 PM
Lock the shift fork over and be done with it.
http://emeraldgreen97.wordpress.com/2011/03/08/renix-era-dana-30-vacuum-disconnect-mod/
Dude13450
03-26-2013, 03:45 PM
Lock the shift fork over and be done with it.
http://emeraldgreen97.wordpress.com/2011/03/08/renix-era-dana-30-vacuum-disconnect-mod/

I'll probably save up some $ and buy a posi-lock cable kit for 160.