This article assumes starting with a tandem truck just off commercial service. It describes the items that we commonly do to “convert” the truck to RV use. While these are things that we commonly do, you can do more or less during a conversion project. The components specified are our recommendations, but other equivalent components are available in most cases. We specify these because we feel they are “best in class”, and are what we use personally.
While you “can” hook up an RV to a commercial truck, the lighting will not work, there will be no brakes, and the commercial hitch will beat the RV up pretty well, in most cases. Some people do run commercial hitches with RVs but we recommend removing the commercial hitch if it is not required for your mission profile – and replacing it with an RV suspension hitch behind the axles.
RVH Lifestyles provides a wide variety of services and products for the recreational HDT community. This article focusses on conversion topics.
The following is our view of the minimum required to convert a commercial truck for RV use.
- Remove commercial hitch
- Add fenders to the wheels to protect the front of the RV. Note this is not necessary if putting on a body.
- Add Direclink brake controller with an appropriate HD module.
- Add TST TPMS (tire monitor) system to the truck, with 6-10 sensors (depending on if you stay tandem). We use the Color display mounted overhead in the storage area. Extra sensors can be supplied for the trailer.
- Add the RVH Electrical center (includes Jackalope). This provides for RV light conversion and the future use of electrical accessories. It includes a DC load center with fuses, and terminal strips to pick up lighting signals.
- Add an ET hitch rated for (typically) 5K-8K pin weight. On a tandem truck, this requires some frame extension – about 2’. The ET sold by RVH Lifestyles has the new upward dampeners in it, the new longer release arm, and the specialized ET head in place of a Binkley head. The ET head is serviceable and heavy-duty – the Binkley head is not serviceable. The ET is upgradeable to (up to) a 10,000 pin weight version if required in the future. Note that in most cases we prefer the ET hitch to a Comfort Ride. We are Comfort Ride dealers as well as dealers for ET, so can supply either, and discuss with you the benefits of both hitches. In most cases, an ET is priced about the same as a Comfort Ride, since it comes with a mounting plate and angle for mounting, while that needs to be added to the Comfort Ride.
- At least one backup camera at the hitch and a 9” monitor at the dash. The monitor is surface mounted. A DVR system that records either 9 or 17 channels or a quad-view camera system is an option. Also, evaluate providing a video hookup at the rear of the bed to support three trailer cameras.
- Wire a 7-way RV blade socket at the rear of the truck for towing an RV trailer. This requires the RVH Electrical Center or the equivalent function. In the picture below you see (on the left) a typical 7-way connector for RV lighting, and below that, a smaller connector for video feeds from the trailer to the Quad monitor or to the DVR system. Three cameras on the trailer can be passed to the truck video system (without sound). Note, the gladhands on the right side are options for air systems, or for easily filling tires.
If you have hydraulic disc brakes on your trialer we can upgrade your trailer brake system to BluDot so that it operates off your truck air system – just like a “regular” semi-trailer. This gives you “best in class” braking for your RV. If you do this a brake controller for electric brakes is not required in the truck, although you might want it to be compatible with a “standard” RV.
- The other thing we do to almost every truck we convert is to change the vertical exhaust stack to a weed burner (horizontal) exhaust. This frees up space for the drom box and allows for additional storage. It also keeps exhaust off the trailer – although with full pollution trucks (trucks with DPF and DEF) exhaust soot is not really a factor).
We generally convert most trucks to single axle from tandem axle. Singling is mostly a personal preference, however, it adds significant cargo space to the bed design, and simplifies ongoing maintenance quite a bit. It also improves maneuvering if done correctly. If carrying any deck cargo heavier than a smart car, we recommend staying as a tandem, since you would likely be pushing the carrying capacity of the rear (single) axle – which is usually rated in the 19,500 lb area. While you could find a 23K-rated rear axle for a singled truck, it is rare to do an axle swap. However, we can do that work if desired.
Singling involves removing the forward-most rear axle and relocating the rearward one. There are three positions commonly used to relocate the axle. “Short” which is to place the axle in the forward position where the “removed” axle was. “Long” which is to leave the rearward axle in its original location. And “Mid”, which locates the axle someplace in between the two original locations.
Generally, we recommend the “mid” (middle) solution, since it balances the looks of most trucks better, and allows for a deck that can carry cargo without excessive cantilever of the hitch. This does require drilling new hanger holes, which the other options do not. So it adds to the work and cost (somewhat). But in the end, you get a better solution.
The exception is if the mission profile requires a truck that is a “daily driver” not designed to carry a car or other significant deck cargo requiring a large(r) deck. In that case, singling short is probably a better solution, since it significantly shortens the wheelbase and provides for a shorter overall vehicle and far better maneuvering capability. If you are driving the vehicle every day, this is a significant benefit. A Volvo 730/780/860 singled short can have a wheelbase as short as 205”, and a 630/640 could be as short as 183”. This depends on several factors, including fuel tank size and position. A singled-mid Volvo 730/780/860 is typically a 236” wheelbase. When singling to carry a smart car, we position the axle at 99” BOC (back of cab) – which is the 236” wb of the 730/780/860.
We never recommend singling “long”. There is no advantage, other than ease of implementation, in doing so and there are significant disadvantages. Mainly, overloading the front axle with deck cargo, significant maneuvering issues vs. mid or short, and looks (the truck looks unbalanced). Singling long may also result in a longer-overall truck since most suspension hitches used with HDTs require being set inside the frame rails. Singling long means having to extend the frame rails to locate the hitch; resulting in a longer overall vehicle than if the axle was more forward, to begin with.
When singling a truck, a new driveshaft must be built for the new length – this is true no matter which position choice is made. A new yoke to attach the driveshaft to the differential is required, and you may have to add/move a carrier assembly to support longer driveshafts. You also relocate airlines, leveling valve, valves/solenoids and support brackets to service the new location. U joints are checked and replaced if required. During this process, we generally clean the frame up and paint it (as required), service/replace brakes, suspension elements, torque arm bushings, etc. Often airbags are replaced, and brake cans are replaced. We also take the opportunity to fully service the cab suspension. This means replacing the airbags, the shocks, perhaps the cab leveling valve, control arm, bushing, and realigning the cab (most of them lean). The ABS brake system is reprogrammed to operate properly and to interface with the Volvo VEST system properly.
There is a great deal of discussion about the value of singling in the HDT community. While you do not have to single a truck, it does have some advantages, and of course some disadvantages. The main disadvantage is the initial cost. Singling, along with the corresponding repairs/improvements discussed above typically averages in the $7,000-$12,000 range. But remember, some of that is actually repairs and improvements, not “just” singling.
One of the things you often hear about singled trucks is that they do not ride as well as tandem trucks. While this may be true in a specific set of circumstances – like going over speed bumps, where the rear is always supported by the tandems – we do not find it to be generally true in RV use. Consider the design goals of the original truck – it is designed to carry significant weight on the rear axles – upwards of 35,000 lbs. And it has a suspension designed for that purpose. So even though it has air ride, it is still pretty “stiff” in the rear when tandem. We have driven the same roads with the same model truck that were both tandem and single and frankly don’t find much difference in them when in RV use or bobtail. This would not be applicable to commercial operation with different loading factors.
Additional items like various bed designs, APUs, lighting, trim/chrome, seating revisions, etc are upgrades to “make your truck your own”, and to provide additional comfort and capabilities. But none are “required” to convert to RV use.
If it can be done to an HDT, we can do the work – from mechanical to appearance items, we do most of the things that make the truck an exceptional recreational hauler.