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RV Towbars - Setting Up Your Vehicle For Flat Towing

Setting Up Your Vehicle For Flat Towing

Mark Quasius
Apr 1, 2011
Photographers: Mark Quasius
When traveling with an RV, half the fun is getting there while the other half is getting around once you've arrived. When towing a trailer or fifth wheel you simply unhook the RV and use your tow vehicle for sightseeing and other daily transportation. When traveling by motorhome you are motorized, so it's just not possible to take it apart and use one half as your local transportation. For this reason the majority of motorhome owners prefer to tow a small vehicle behind the motorhome. This vehicle can be anything from an economical car to a serious off-road capable SUV, or anything in between depending on what type of recreation the RVer is looking for.
Photo 2/12   |   rv Towbars Vehicle Flat Towing motorhome
Four Down
A larger number of vehicles are capable of being flat towed, which is also known as towing "four down." This method involves connecting the towed vehicle to the RV with a towbar and allowing it to follow along behind. Not every vehicle is capable of being flat towed and the majority of the time it is due to limitations of that particular vehicle's driveline. In some cases driveshaft disconnects or electric transmission lube pumps can be added to prevent transmission or transfer case damage so that these vehicles can be flat towed. In some cases it's just not possible to flat tow that particular vehicle and a tow dolly may need to be used. However, there are a large number of vehicles that are capable of being flat towed with no modifications to their driveline. Various on-line charts are available, such as those published by Family Motor Coach Association, that will list which vehicles are capable of being flat towed and which are not.
Photo 3/12   |   After towing a Jeep Grand Cherokee for three years, we bought a '05 Jeep Wrangler. We wanted to tow this vehicle to the various off-road destinations, so I set this vehicle up for towing.
Once you have determined that you have a vehicle that can be flat towed, the next question is what you need to have to be able to tow that vehicle. There are four main areas that need to be addressed: the towbar itself, the towed vehicle base plate, lighting, and auxiliary braking systems.
Towbars Defined
Towbars have come a long way since the original A-frame devices that attached to the front of the towed vehicle and swung down to connect to the RV with a ball hitch coupler. Today's towbars are attached to the motorhome rather than the towed vehicle. Rather than a rigid A-frame design, these units consist of two telescopic tubes that connect to mounting lugs on the towed vehicle's base plate.
Photo 4/12   |   When not in use, the towbar stows out of the way on the motorhome.
You no longer have to have to obtain perfect alignment. Just get it close, extend the arms a bit, and connect them to the base plate. Then you either back up the towed vehicle or pull the motorhome forward a bit to fully extend the arms, which then lock into place. When you are finished towing you simply pull the pins to disconnect the arms, collapse them, and the whole unit swings up and over to one side for storage without ever being removed from the motorhome. The towbars are universal and can connect to any number of different towed vehicles.
Base plates are unique to each towed vehicle. They are designed to fit each exact frame configuration so there is no "one size fits all" model. Some base plates feature removable tabs. When these tabs are removed the towed vehicle looks like any other vehicle and you would never know that it was towable. This gives you a nice clean look and also eliminates any shin smacking tabs from protruding out the front of the vehicle. The base plate serves as an adaptor that allows you to safely connect your towbar and safety cables to your towed vehicle.
Photo 5/12   |   The base plate bolts to the Wrangler's frame to provide a solid attachment point for the towbar.
Auxiliary Lighting
Auxilary lighting is another necessity. The motorhome will have a trailer lighting socket so it's easy enough to connect an umbilical cord between the RV and towed vehicle to operate the vehicle's taillights, brake lights, and turn signals. All that remains is to attach a lighting socket at the front of the vehicle and connect to either the existing lights or run a new set. Many taillight housings are large enough that you can easily add an extra bulb and socket to be used for the lighting when being towed, which eliminates the need to tie into the existing wiring harness. In other cases a diode pack can be installed to use the existing lighting system so that the existing taillight bulbs can be shared between the RV and towed vehicle. Every towbar manufacturer will have detailed charts that show which lighting method is applicable for your vehicle. In worse case scenarios, portable magnetic lights or lighting bars can be used.
Photo 6/12   |   The Wrangler's base plate had non-removable mounting lugs as well as connection points for the safety cables.
Auxiliary Braking
Lastly, an auxiliary braking system should be considered. While not universally required by law, certain states and provinces do have regulations regarding auxiliary braking on towed vehicles. They are not under the same category as trailers so it can be hard to get exact facts on just what the law is. Regardless, it is a good idea to have an auxiliary braking system. Pulling a small vehicle behind a large, heavy RV may not make a huge difference in stopping distance but it will be noticeable and may be the difference between stopping in time or a collision with another vehicle. In addition these systems provide brake lock up in a breakaway situation. Should your towed vehicle ever come loose from the motorhome it would be a dangerous projectile capable of causing serious injury or death. A breakaway system will prevent this from happening by locking up the towed vehicle's brake and bringing it to a stop should it become disconnected when towing. For that reason alone an auxiliary braking system is worth its weight in gold.
Photo 7/12   |   The '05 Wrangler prior to towing set-up. To fasten the base plate to the frame a number of captive nuts with feeler rods were supplied with the base plate.
After towing a Jeep Grand Cherokee for 3 years we bought a 2005 Jeep Wrangler. We wanted to tow this vehicle to the various off-roading destinations so I set this vehicle up for towing. This Jeep had the factory off-road front bumper and winch setup. The steel bumper afforded us a number of places to install the lighting socket, breakaway switch, and towing brakes air-hose connection. I had a Blue Ox Aventa LX towbar on the RV so I purchased a Blue Ox base plate for the Wrangler. Unfortunately, this base plate had fixed tabs rather than the removable tabs found on my Grand Cherokee, but it was a Wrangler and had a utility look so it didn't really affect the cosmetics.
Photo 8/12   |   The M&G auxiliary braking system installs between the master cylinder and vacuum booster and offers proportional braking of the vehicle's brakes when being towed.
On the Grand Cherokee the taillights were large enough that I could install a separate set of lighting sockets in them. The 2005 Wrangler lights were more compact so I chose to add a diode pack to tap into the existing taillight wiring harness instead. I used a hole saw to bore a hole in the front bumper and mounted the lighting socket there. The lighting system only required four wires, but my umbilical cord was a six-wire type, so I installed a six-wire socket on the Jeep. I then ran a charge wire that connected the batteries on the RV with the Jeep battery so that the RV would keep the Jeep battery charged while towing. Circuit breakers were installed on each end of the wire to prevent any potential short circuits from damaging the wiring.
Photo 9/12   |   A trailer light socket, breakaway switch, and air brake hose connection were installed in the Wrangler's front bumper to facilitate connections to the motorhome.
For an auxiliary braking system I chose a unit made by M&G engineering. This ingenious unit installs between the brake master cylinder and the vacuum booster. It consists of two opposing pistons. When air pressure is applied between the two pistons, the front piston moves forward, applying the brakes. Because our motorhome was a diesel pusher, it had air brakes and it was just a matter of connecting the RV to the M&G system via a quick disconnect air hose. With this system the Jeep's brakes work whenever the motorhome brakes are applied and they are totally proportional so it's a great system. When the vehicle is driven normally, and not towed, the module acts as a large pushrod and is totally failsafe. In the event of a breakaway, the breakaway switch will actuate an electric solenoid that drains a small under-hood air tank into the M&G module to apply and lock up the brakes. For those who do not have air brakes there are a number of electric braking systems available from other vendors, such as US Gear, SMI Engineering, and Brake Buddy.
Photo 10/12   |   Locking pins were used to ensure safe and secure attachment of the towbar to the vehicle.
Once the wiring was in place, I installed the M&G module between the master cylinder and vacuum booster. The small air tank reservoir was mounted under the hood and connected to the M&G module via the electric air solenoid. Next, the breakaway switch was attached to the front bumper and the breakaway cable was cut to the proper length and the end was crimped. A male quick disconnect fitting was installed on the bumper for an easy connection to the RV. The RV's braking system was tapped into and a female quick disconnect coupler was installed near the hitch. All I needed to do was connect a short air hose between the two vehicles to connect or disconnect the system. A spark plug boot with short piece of nylon airline was added to serve as a dust cover when not towing.

Once the Jeep was set up with its new base plate, lighting system, and auxiliary braking system it was just a matter of hooking up the Jeep to the motorhome. For this task I decided to use a locking hitch pin set. These sets come with three identically keyed locking pins. The 5/8-inch hitch pin holds the towbar into the receiver, while the two 1/2-inch pins secure the towed vehicle to the towbar. This makes for a secure locking system that won't come apart during travel.
Photo 11/12   |   It's important that the towbar angle is within proper specifications. Excessive angles may lead to vaulting or submarining of the load under hard braking.
Quick And Easy
Hooking up the Jeep to the motorhome is a quick 2-minute process. You first connect the towbar to the mounting lugs on the base plate and back the Jeep up until the latches engage with a click. The safety cables are then connected, which must be crossed beneath the hitch, the lighting umbilical, and the connecting hose for the brakes. I chose to pass the breakaway cable and air hose inside the lighting umbilical to keep things neat and prevent anything from dragging. The last step is to slide the transfer case lever into neutral and insert the dummy key to the first position to free up the steering.
Photo 12/12   |   Flat towing gives you the freedom to explore unique areas in your own vehicle.
You need to have the steering unlocked so that it can follow the RV's movements when being towed. This is done by inserting the ignition key and turning to the first position. On some vehicles simply placing the key into the ignition activates circuits that can drain the battery. In these cases you can pull a fuse to prevent this from happening or install a cutoff switch in the dash to kill power to the key switch.
It is critical to verify the height of your hitch. If the towed vehicle is higher than the motorhome's hitch, it will vault over the top during an emergency stop and impact the coach's rear. If the vehicle's towbar lugs are too low, it will tend to dive under the RV. The RV is fairly heavy so it won't be lifted by the towed vehicle, but this will remove weight from the rear axle and reduce the RV's braking ability at the time it needs it the most. An ideal towbar height is to have the towbar level or else have no more than a 6-inch drop from the RV to the towed vehicle. If your height differences are not within these allowable parameters, a drop hitch adaptor is available.
Flat towing is a great way to bring your daily vehicle along with you when traveling by motorhome. It's a snap to connect or disconnect from the RV and you have a greater choice in which vehicle to tow. You can choose a smaller, more economical vehicle for sightseeing and performing those daily errands or your favorite SUV for hitting the off-road trails. Towing "four down" is definitely "two thumbs up" in my book.


Blue Ox
Pender, NE 68047
Brake Buddy
Emporia, KS 66801
Demco Manufactoring
Boyden, IA 51234
Family Motor Coach Association
Cincinnati, OH 45244
Vancouver, WA 98682
SMI Manufactoring
Newburgh, IN 47630