I have a 88 Cherokee with AW4 and Command-Trac with a stock vacuum motor actuated front-disconect axle. I always stop to shift into 4WD and have never had any problems.
However, I have read that Command-Trac can be shifted "on-the-fly". If the car is in 2WD, the front driveshaft is not turning and the ring gear in the open differential is stationary. Since the driver-side wheel is splined to an axle and the axle is splined to the differential side gear ( inside the open-differential), and the side gear is meshed with one spider gear(pinion). This spider gear is also meshed with the side gear on the passenger-side. Since the ring gear is not moving, the two (2) spider gears and two(2) side gears(inside the differential ) rotate in opposite directions. Likewise, the passenger-side intermediate axle shaft (before the vacuum disconnect housing) is rotating backwards, while the passenger-side axle shaft from the passenger-side wheel is rotating forward. So if the car is moving forward and I attempt a shift "on-the-fly" the splined shift collar(in the axle shift motor housing) will attempt to couple two axle shafts rotating in opposite directions. This is not good! What am I missing here? Is there some type of vacuum delay that allows the ring gear to start rotating first to drive both side gears in the same forward rotational direction, before the shift collar attempts to couple the intermediate axle shaft with the passenger-side wheel axle shaft?
Best regards,
CJR
However, I have read that Command-Trac can be shifted "on-the-fly". If the car is in 2WD, the front driveshaft is not turning and the ring gear in the open differential is stationary. Since the driver-side wheel is splined to an axle and the axle is splined to the differential side gear ( inside the open-differential), and the side gear is meshed with one spider gear(pinion). This spider gear is also meshed with the side gear on the passenger-side. Since the ring gear is not moving, the two (2) spider gears and two(2) side gears(inside the differential ) rotate in opposite directions. Likewise, the passenger-side intermediate axle shaft (before the vacuum disconnect housing) is rotating backwards, while the passenger-side axle shaft from the passenger-side wheel is rotating forward. So if the car is moving forward and I attempt a shift "on-the-fly" the splined shift collar(in the axle shift motor housing) will attempt to couple two axle shafts rotating in opposite directions. This is not good! What am I missing here? Is there some type of vacuum delay that allows the ring gear to start rotating first to drive both side gears in the same forward rotational direction, before the shift collar attempts to couple the intermediate axle shaft with the passenger-side wheel axle shaft?
Best regards,
CJR