Towing a Car Behind Your Rig
Why Tow a Car
If you're reading this, you probably already know why you want to tow a car behind your rig, especially if your rig is a large one. There are just so many places you can't take a big rig and there's often no good place to park it. Before I began towing a "toad" (AKA "Dinghy") I used to get quite jealous when I watched people unhook their toads and drive happily off to see the sights. Getting a three-figure parking ticket at the Grand Canyon when the rear end of my rig stuck out a little too far and partially blocked traffic convinced me for good. I set my rig up to tow a car and never looked back. Unless you're driving a camper van or using a pickup camper, you'll definitely be glad you opted for a toad.
Four-down Versus a Dolly
There are two basic methods for pulling a toad behind your RV: a tow dolly and what's called "four-down" towing.
You can get a two-wheel tow dolly that attaches to the hitch on your rig. You drive the car's front wheels (presumably it's a front-wheel-drive machine) up onto the dolly, secure the front wheels with straps, plug in the umbilical cord so you'll have turn signals and brake lights in the toad, and drive off. There are two major disadvantages of a tow dolly, however. First, you have to do something with the dolly when you're not using it. Some will fit under the rear of the rig (if it's high enough), but any good dolly is heavy and hard to move, especially if the ground is wet. You can't back up the rig with the dolly attached if the dolly wheels swivel and most back-in sites don't have room for it anyway, so camping in a back-in site with a dolly can be very unpleasant, especially if it's raining. Second, hooking up can be a major pain. You have to wrap the straps very tightly around the front wheels (which might be covered in mud), and no matter how tight you get them, they will come loose after you drive for a while (especially if it's raining) and you'll have to pull off the road and do it again. Worse yet, there's no way to know if they've come loose or not, so you'll never feel quite safe without stopping periodically to check them. On the plus side, if you have a dolly with fixed wheels (that don't swivel), you can back up, which you can't do towing four-down. If your dolly has surge brakes, and many do, you don't need to install any auxiliary braking system in the toad. With a dolly, you'll also save wear and tear on your front wheels and front suspension.
The other option is to tow the car "four-down," — i.e., with all four wheels on the ground. In that case, you hook up the tow bar and the umbilical cord and you're off. When you get where you're going, you unhook — about 5-10 minutes and you won't get dirty doing it as long as you wear gloves. Nothing to stow, nothing to wrestle with, and you can back up at will (once the toad is removed). There is a down side, though. You'll get more wear on your front tires (the tires of your dolly will also wear, but they're probably cheaper tires), and you'll spend significantly more money getting the toad ready to tow. With a dolly, you need the dolly and light wiring. Going four-down, you'll need wiring, an auxiliary braking system, a base plate/tow bracket, and a tow bar. You may also need a way to disconnect the drive shaft if you have a rear-wheel drive car with an automatic transmission. That said, I strongly recommend four-down towing if you can afford it.
Which Car to Tow
You can tow just about any car behind your rig if you're willing to modify it (and it's not too heavy), but it's a lot easier and less expensive if you get a car that can be towed four-down as is (on some you have to remove a fuse). Blue Ox has a pretty complete listing of what cars will do that: 2010 Towing Chart. The chart is for 2010 vehicles, but it will give you a general idea of which vehicles can be towed four-down. You can search for specific vehicles at both Blue Ox and Roadmaster.
Personally, I would stay away from using a transmission lube pump because it can fail without you knowing about it and ruin your transmission. I use a driveshaft disconnect on my Mustang, which is pretty foolproof. Once I pull on the cable under the driver's seat of the toad, the rear wheels are completely disconnected from the transmission and can spin freely. It makes a very disturbing noise when you reconnect it by pushing the cable back in with the car running in neutral, but it's harmless and you get used to it — though heads will definitely turn if you do it around other people.
The weight limit is not a trivial issue. Your rig has a towing weight limit. If you exceed it, you may not have handling problems (though you might), but you risk breaking your hitch and your tow bar, your stopping distance will suffer, your brakes will wear faster (and possibly fail coming down a mountain pass), and your ability to control the rig in a panic stop will be compromised. If you have an accident, the police, and possibly your insurance company, may check the weight limit and the weight of your toad. When you figure the towing limit, be sure to include the weight of any stuff you will be carrying in the toad. I often see small rigs pulling a pickup or SUV loaded with a ton of gear that almost certainly puts them way over the limit.
When shopping for a toad, consider getting a convertible. I've driven my Mustang convertible with the top down on Highway One in California, around Lake Tahoe, through Yellowstone, Glacier, the San Juan Islands, the North Cascades, up Minnesota's north shore, all over Florida, and through countless other state and national parks. Thinking about seeing all those places in an enclosed vehicle just makes me sad. One caveat: convertibles tend to be heavier because they add extra steel to stiffen the frame, so check the towing capacity of your rig and the weight of any convertible you're considering. The Mustang (a V6) is close to the limit on weight, but I chose it over other convertibles because of the trunk space. I looked at the BMW Z3 and Z4, the Mitsubishi Eclipse, and the Miata, all of which could be towed, but their trunks will hold a loaf of bread and not much more. A BMW 3-series convertible would also be a good choice (and would tow nicely with a manual transmission) if you can afford it.
Of course you can also save quite a lot of time and money if you buy someone else's toad that already has the wiring, surge brakes, base plate, and tow bracket installed — in some cases you'll also get a tow bar. A web search (without the quotes) for "RV toad for sale" and "RV tow-car for sale" will turn up a few. You can also ask in one of the many RV user groups and forums — someone will almost certainly know of a toad for sale.
Stuff You'll Need to Tow Four-down
To tow a car four-down, you'll need a number things to make the car towable. A tow bar plugs into the receiver on your rig's hitch. You definitely want a tow bar with telescoping arms, though it will cost more. With telescoping arms, you don't need to position the toad exactly to hook up. You've got at least a foot of leeway, and once you get used to it, it's very easy to position the toad so you can hook up easily.
You'll need a base plate/tow bracket (Blue Ox calls them base plates, Roadmaster calls them tow brackets) for the vehicle. The base plate/tow bracket attaches under the front end of the toad and is securely bolted to the frame. They can be fairly easy to install, or not. I put the one on my Mustang and I had to remove an existing plate under the engine, hold the towing base plate in place, and reattach the existing plate below it. The bolt holes didn't line up exactly and I had to use some muscle and a crowbar to get the bolts started. If I had an assistant and a lift, it would have been much easier. For some cars, you may need to remove the front bumper and loosen or remove the front quarter panels to install the base plate/tow bracket. For some cars, you may also need to modify the front end of the body by cutting holes in the grill or the cowling. My Mustang didn't require any modification for that. Usually, the necessary modifications are listed on the web page that describes the base plate/tow bracket. When you shop for them online, you may be able to see a photo of how the car will look with the bracket removed.
Selecting a Tow Bar
You definitely want a tow bar that has telescoping arms and I prefer one that stays with the RV rather than hanging on the front bumper of the toad. Many setups have the option to remove the front part of the tow bracket when you're not towing so the car looks more-or-less normal when not being towed.
Where to Buy Tow Bars and Brackets/Base Plates
The two main sources of tow bars and base plates/brackets are Blue Ox and Roadmaster. Both make excellent tow bars and brackets/base plates. For my Mustang, the Roadmaster bracket was much more attractive and easier to install, but I'm not sure that's true for all vehicles.
Lights and Turn Signals
The law requires that your toad have working brake lights, tail lights, and turn signals. You can wire things so that the toad's own lights work as they do when you are driving it. You can use the car's lights after wiring in some diodes. I think the diodes are not strictly necessary on all setups, but they prevent damage to the electrical system on some vehicles and are good insurance. I did all the wiring myself, but most trailer hitch shops can do it for you. You can also get very inexpensive add-on lights and use those, but there is some risk of damage to the car's finish and you have to install and uninstall the lights and store them when you're not towing. They can also grow legs if someone wants a five-finger discount.
Auxiliary (surge) Brakes
Some people pull a toad without any auxiliary braking system at all, but I wouldn't do it. Your stopping distance will suffer, and having the extra braking power might mean the difference between stopping safely when the vehicle in front of you makes a sudden stop and totaling the car, injuring any passengers, ruining the front of your RV, and wrecking your vacation. I can adjust the sensitivity of my brakes while driving the rig and I can definitely feel the difference when I try to stop with the auxiliary brakes turned off. I've also heard of cases where an RV driver lost the rig's brakes and was able to stop by using the toad brakes. You also have to consider the possibility that the toad may someday come unhitched. With auxiliary brakes, the toad's brakes will go on automatically when that happens and the toad will stop. You can imagine what will happen in that case if the toad (which is in neutral) doesn't apply the brakes at all. It may go off a cliff, over a pedestrian, or into another car. If your safety cables hold (and they may not depending on where the break is), the toad will hit the back end of your rig. If the broken tow bar is still attached to the toad and sticks in a pothole or hits a curb, the toad may do a front somersault. Most states require auxiliary brakes for anything you tow over a certain weight, and in most of them your toad will be over that weight. If you have an accident without auxiliary brakes, the police and your insurance company may not approve.
For surge brakes, an easily installable unit like the Brake Buddy is popular, but you have to uninstall it whenever you want to drive the car and store it somewhere. A more expensive option is something like the US Gear Unified Tow brake which remains in the car, out of the way, and uses its own compressor connected to the brake vacuum lines so you have true power brakes all the time. I installed mine and it was a pretty major job, but I'm happy I spent the extra money on it and don't have to do anything at all when I want to drive the car or tow it.
If I were doing it today, I think I'd get SMI's Stay-In-Play system. I haven't tried one, but several people I know are really happy with it and I think it's an easier, less obtrusive install than the US Gear unit.
Wiring Between the Rig and Toad
For the wiring, a 7-pin connector and umbilical cord is probably the best option. eTrailer has a nice wiring diagram here (though it doesn't show the diodes). There's a diagram here that shows the diodes. You can improve the contact by bending out the flat plates inside the female end slightly with a small screwdriver. Be careful not to bend them out too far or the plug won't go in. Northern Tool has all the parts you need to make your own umbilical cord and connectors. You may already have a blue wire with a bare end under the dash (near the steering column) that runs to the the back bumper of the rig. That's for use as a brake controller line if you need one. You can also run a 10 gauge wire from the positive terminal of the rig's battery (be sure to put in a fuse) to the positive terminal of the Toad's battery (through the umbilical cord) so that the toad's battery doesn't run down on long trips. It's a pain to arrive at a campground with a dead toad battery (and it shortens the life of the battery). I only needed 6 wires for the brakes, charge line, and lights. I used the 7th as an auxiliary ground connecting the frame of the rig with the negative terminal of the toad battery just to make sure that everything in the toad has a good ground.
Most, but not-all, manual transmission cars can be towed four-down in neutral. On some cars, you need a lube pump to provide lubrication to the transmission while towing, though I've always been wary of those because if the pump fails, you won't know it until your transmission is toast. Some automatics can be towed four-down either as is, or after disconnecting a fuse. Motorhome Magazine has some good information on which cars can be towed four-down (they call it "flat") here.
If you have a rear-wheel drive automatic, you may need a way to disconnect the drive shaft with a drive-shaft coupling to tow four-down. In that case, a cable runs from the back of the drive shaft to a spot under the driver's seat. When you pull out the knob, the drive shaft is no longer connected to the rear end so the rear wheels can spin freely without moving the transmission. It's not very intuitive, but when towing with a drive shaft disconnect, you put shift lever in Park. When buying a drive shaft disconnect, you have the option of getting an attachment for your current drive shaft, or a whole new drive shaft with the disconnect attached to it. I recommend the latter.
For front-wheel cars, you can install an axle-lock coupling, which works like the drive shaft disconnect but for both front axles.
For more information on drive-shaft and axle-lock couplers, look here.
As you might guess, after you've done all the things described above to make your toad towable, you'll have spent a fair amount of money, even if you do most of the work yourself, but most of the stuff can be moved to a new rig and/or a new toad, and if you do some of the work yourself, you'll know how to do that.
It's cheaper and easier to get a used tow dolly with built-in surge brakes and any front-wheel-drive car, but then you have to store the dolly and hooking up is more of a pain. After watching a few people hook up with a dolly at a muddy campground in the rain, I'm really glad I went four-down. Personally, I think the only way a dolly makes sense is if you have more than one toad to pull.
Thank you for visiting BobsGuides.com
— Bob Ray