All-Wheel and 4-Wheel Drive TowsFeb 12th, 2010 | By Editorial Staff | Category: Ask the Pros, Ed Johnson
ANSWER: The only simple answer is to All-Wheel Drive vehicles: Do not tow them with any wheels on the ground UNLESS you have specific information for the individual vehicle that states that towing is appropriate and that tells you how. Few AWD vehicles can be towed without doing severe damage to the drive system. In the case of “viscous drive” (fluid drive) vehicles, moving just a few feet can build up pressure that will destroy the “viscous differential” (liquid clutch or differential). In most cases, the liquid drive unit will cost $2,000 to $3,500 to replace. Other systems such as the chain drive transfer case in the Jeep Quadra-Trac will break the chain almost immediately and can destroy the drive gears it is attached to. This can easily cost $1,000 to $1,500 to repair. Other systems on the market use a direct drive all-wheel drive system consisting of gears and differentials that allow the wheels to move at different speeds (as happens when making turns) but will break if any of the wheels are blocked so they cannot turn at all; as would happen with a wheel-lift tow.
Generally, most 4-wheel drive vehicles can be towed but only if they have a “2WD”, “2H”, or similar notation that a 2-wheel drive option is available. In some of these vehicles, the drive can only be changed to “2WD” from a 4-wheel drive mode if the engine can be started. If the engine cannot be started, the 4-wheel / 2-wheel shift control will move but it will not shift the transfer case and the vehicle will remain in 4-WD mode regardless of what the shifter indicator shows. These vehicles depend on engine vacuum to operate the drive system and with the engine off, moving the shifter will not make any difference.
Most vehicles that have a cable driven 2WD / 4WD transfer case shifter can be towed regardless of what drive the vehicle was in before the break-down and the engine does not have to be operating to make the change. This is because the cable shift (sometimes actually a rod shifter) will move with the shift control. These vehicles can generally be towed in the 2-wheel drive mode or the “neutral mode” with no problem for distances of 50 miles at 35 miles per hour.
Vehicles that have a manual hub on the front axles that have a “unlocked” or “free” indicator can be towed from the rear at unlimited speeds and distances if the manual hub is turned to the “unlocked” or “free” position.
The speeds and distances for towing 4-wheel drive vehicles vary widely and unless you purchase a tow manual that provides this data, you will be better off to tow most of them on a wheel-lift and dolly or transport on a rollback.
The AAA towing manual is conservative in its approach to transporting 4WD and AWD vehicles and will in most cases tell you not to tow them with any wheels on the ground. If you tow for AAA, your local club will generally give you as many copies of the manual as you need at no cost to you. Currently (I believe), it covers most vehicles built since the year 2000.
Ford towing manuals covering the years 2000 through 2007 can be downloaded from the internet at no charge, but you must carefully read them or you will make mistakes. The diagrams cannot be depended upon fully for instructions, the written instructions must be fully followed and in some instances, the diagram and the written data do not match.
Johnson’s Guide (written by me) gives very detailed but simple to follow instructions for towing most vehicles built between World War II and the year 2002. Johnson’s Guide will give you towing instructions specifically designed for the exact drive system in each vehicle and therefore makes it possible to tow considerably more vehicles than the AAA manual allows.You do however, have to buy this manual for $34.95. A new manual will come out in 2007 which will provide towing data for most vehicles sold in the United States from 1925 to 2007 but the cost of this manual will probably be about $59.95. The manual may be ordered by calling 757-827-6524.
Many tow operators take very expensive risks when towing AWD and 4WD vehicles and the damage I have seen a lost of them damaged. Unless you have specific instructions for how to tow a specific vehicle, I urge you not to take these risks.