Planet 4x4 - 4x4 Posi Lok Installation

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Product Reviews - 4x4 Posi-Lok Install

The automatic 4x4 actuator had, yet again, gone out on our '92 GMC tow rig. Not interested in fixing a weak setup, it was time for a 4x4 Posi-Lok system to be installed.

The 4x4 Posi-Lok comes with all of the needed hardware to replace the OEM setup with a manual setup. This puts a push pull knob in the cab that allows the driver to manually engage and disengage the front axle at will. The OEM setup involves a switch at the transfer case that sends power to a thermal setup. This thermal setup is basically an element that heats a cylinder of gas. When heated, the gas expands and that engages the front end. The problems with this is that the element will burn out or, and this has happened to us, the front end is in snow or its a very cold day and the gas cannot get warm enough or it takes forever to work. With ours dead, we placed a call to Steve at CBI OffRoad and he got one in for us fast. The kit also came with a great set of instructions with nice big pictures so that even we could get it right.


First step is to mount the bracket into the cab of the truck. The kit came with two different brackets as the '95 and up dash is different.


Here is the bracket fully mounted up. Two holes were drilled into the metal support for the dash and screws hold it in place.


Cut away a little bit of the firewall insulation above the gas pedal mount. This is where the cable will be going through.


The directions specify a 9/16" drill bit. We only had a 1/2" drill bit so we used that and used a slightly smaller rubber grommet for the hole. The kit comes with one for the bigger bit.


Here is the cable being installed. There is a nut that goes on the back and holds it all into place.


Knob in place and tight. Out of the way but easy to reach.


Here is how we ran the cable in the engine compartment. We used one of two supplied zip ties to hold it to the brake cylinder to keep it away from anything hot and or moving..


Here is the original setup. Dead and Ugly.


Here is the evil thing. It would have been easy to just swap it out. But it would only have been a matter of time.


All of the brackets mounted. On the left is the pivot setup and the right is to hold the cable in place.


Same thing as the last but now the cable is mounted to the bracket.


Next step is to assemble the actuator. Here are the parts laid out in order. We filled the boot up with grease to keep the shaft clean and lubed.


Actuator all assembled. Piece of cake!


Screw in the actuator and hook it to the pivot and tie in the cable. Here it is in the unlocked position.


And here it is in the locked position.


Handle unlocked for 2x4

Handle pulled out for front end engagement.

The nice thing about this is that it gives you the option to run in two wheel drive, low range. Very handy when backing up large trailers and such. Now when I reach down, I know that the front end is going to lock in. The last time the old setup died, we were pulling a fully loaded trailer of rocks up a steep muddy driveway. Not a great place to be stuck.

Posi-Lok also makes systems for Dodge, Ford and Jeep applications. To find out more, check them out at

Planet 4x4


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