4x4 Posi-Lok - Absolutely, Positively LockedPosted in How To: Transmission Drivetrain on April 1, 2007
Ever lost 4WD and you didn't know why? The front driveshaft was spinning and nothing was broken...yet it didn't work regardless? Do you have an IFS Chevy or a Jeep or Dodge with Central AxleDisconnect (C.A.D.)? How'd we guess? Hmm...a correlation!
There are a lot of Chevy, Dodge, and Jeep 4x4s running around with some ill-conceived 4WD systems: trucks with 4WD actuators that engage the passenger axleshaft to the differential, utilized in an effort to minimize the front drivetrain's impact on fuel economy. These actuators can be found on early XJs and all YJs, '85-'02 Dodges, and the '88-'98 Chevy fullsizes and all S-Series 4x4s. The Chevy fullsizes used a thermal linear actuator that engaged when it heated up (we're sure you can already figure out problems with this one), while Dodge and Jeep used a vacuum actuator that engaged when a vacuum boss in the transfer case allowed suction to come through the hoses.
Junk! All of it! All the OEMs did was add more things to go wrong with your 4WD system. But 4x4 Posi-Lok has been building solutions for the actuators for a long time now. The Posi-Lok is a replacement mechanical actuator that engages the axleshafts with a pull of a cable. The installation time on our Chevy was about two hours, and that's just because we were missing a 1/2-inch drive-deep socket. It's cake to get rid your of stock crud, and it costs less than $200 to do so.