4x4 Vans : Quigley Motor Company, Inc. > Technical Center > GM Tech Center > Operation Instructions

Operating Instructions

Instructions for IFS 4x4 System

The Quigley GM vehicles utilize a front locking differential Independent Front Suspension (IFS). This 4x4 system is devoid of either manual lock-out hubs or automatic locking hubs. Instead, the differential electronically engages the front axle halves into the 4-wheel drive application when the vehicle's transfer case is shifted. 

CAUTION: When transfer case is in "N" (neutral), the transmission "PARK" feature is disabled. Parking brake must be applied or vehicle may move unexpectedly, causing serious injury or death. True for all Quigley 4x4 GM systems, IFS and Solid axle.

Best Practices: No matter what type of GM Quigley 4x4 system you have, shift into 4WD only when conditions require traction. When the need for a 4-wheel drive is no longer anticipated shift transfer case back into the 2H position.  If vehicle is equipped with manual hub locks return them to their "FREE" position, by turning them counterclockwise, at a convenient time and location.  For best fuel economy, less tire wear and quietest operation, the manual hub locks should be in their “FREE” position if so equipped and vehicle should be returned to 2H.

The Quigley IFS 4x4 system can be shifted from 2-wheel-high (2H) to 4-wheel-high (4H) or from 4H to 2H while the vehicle is in motion up to speeds of 55 mph. However, you may not shift into 4H while accelerating. In extremely cold weather, it may be necessary to stop or slow the vehicle to shift into 4H.

To shift into or out of 4-wheel-low (4L) slow vehicle to a crawl (1 – 3 mph) and shift the transfer case lever in one continuous motion to 4L. DO NOT PAUSE in the NEUTRAL (N) position as you shift the transfer case or your gears could clash. If clashing of gears occur then turn off the engine and proceed to shift into 4L.

First Generation IFS and Solid Axle 4x4 Systems

To prepare your vehicle for 4x4 operation you must first lock your manual hubs. Simply turning your front wheel hub selector knobs clockwise to their “LOCK” position does this. Slight movement of the vehicle in either direction will complete the lock. Both hub lock selector knobs must be set in the same function to avoid excessive front differential wear and undesirable vehicle handling characteristics.

4WD High Range: Shift the transfer case to 4H only when conditions require traction. Vehicle’s transfer case can be shifted between 2H and 4H while in motion at speeds up to 55 mph, provided both of your manual hub locks are in their “LOCK” position. CAUTION 4WD Low Range: For both shifting into and out of 4L the vehicle must be stopped and the TRANSMISSION must be in N (Neutral) whether you have manual hubs or automatic hubs. Never shift into or out of 4L while vehicle is in motion. Please download and review detailed operating instructions before engaging 4WD Low range.