Tongue Tonnage

Dear RV Doctor, we have a 1996 1/2-ton Chevrolet truck with a 5.7 liter engine and a 3.73 axle ratio. Our owner's manual says we can safely tow 7,500 pounds. We are now towing a 1997 Wilderness travel trailer (no slideout), and are having no problems whatsoever with towing. Our ride is smooth and we never feel a big strain on the engine. We are thinking about selling our trailer and getting a new Wilderness with a slideout. The UVW on this trailer is about 6,400 pounds, but the hitch weight is substantially higher than with our current trailer. My question is, how important is hitch weight and what happens if your hitch weight is too much for your tow vehicle? I have heard from other RVers that if the hitch weight is too high, your front wheels on your tow vehicle may come off the ground at times and it will be hard/unsafe to drive. What are your opinions on this?

---Ellen Boone, Butler, MD

Ellen, knowing the correct hitch weight, or "tongue weight" as it is sometimes called, is crucial in order to establish a safe towing configuration with any conventional travel trailer. More prevalent in years past, inadequate tongue or hitch weight was a significant contributor to trailer sway. With today’s engineering standards being more defined, this probable cause from the past has been lessened quite a bit. Still, in terms of most hitches, the ideal tongue weight should be at least 12% of the total weight of the fully loaded trailer. Some of the larger trailers may have tongue weights nearing 17% of the total. Anything less than 12% could have a tendency to be the cause of trailer sway. If the tongue weight is extremely heavy, such as your fear, the majority of stowed objects may need to be positioned aft of the axles rather than in front of them. In any case, it will be necessary to have your towing configuration properly weighed on a platform scale to determine the optimum positioning of all the stowed gear. All this assumes you are using a weight distributing hitch, by far the most common type of hitch today. As a point of reference, refer to this weight capacity chart:

            Class                Type                            Capacity

                I                   Weight Carrying             2,000 GVW

                II                   Weight Carrying             3,500 GVW

                II (torsional)   Weight Distributing         3,500 GVW

                III                  Weight Carrying             5,000 GVW

                III                  Weight Distributing         10,000 GVW

                IV                 Weight Distributing         10,000 GVW

                V                  Weight Distributing         15,000 GVW

Always mounted to the frame of the tow vehicle, this type of hitch, by its design, distributes the weight to both axles of the tow vehicle. Weight distributing hitches are the preferred method of towing all but the lightest forms of travel trailers. The weight distributing hitch works in concert with tongue weight and all but eliminates your concern of putting too much weight on the rear of the truck. A properly adjusted set of spring bars, in conjunction with a properly sized weight distributing hitch, will shift a portion of the tongue weight to the front axle of the tow vehicle. Your front tires will never leave the ground!

Add-on A/C

Dear Gary, I am interested in installing a second air conditioner in my fifth wheel where the vent currently is located in the bedroom upstairs. I know I have a breaker in the box marked “2nd air conditioner,” but I’m not sure if I can actually install one there. Could you please advise me on what I need to look for to make sure I can install one before I buy.

---Jim Grindley, Augusta, GA

Jim, your coach is apparently pre-wired for that second roof air conditioner as is evidenced by the presence of the second circuit breaker in the panelboard distribution box. If you remove the inside garnish (trim) piece from around the 14-inch roof vent at the ceiling, you should find a hole through one side of the cutout opening. There’s no need to remove the vent itself from the roof for this inspection; you’ll be able to verify this from the inside. Chances are there is also a flat, blank cover plate near that side of the ceiling right across from the vent opening. Inside that ceiling box you should find pre-installed conductors routed up from that second circuit breaker. Whoever installs that second roof A/C will have to route a short section of Romex cable from that junction box in the ceiling over to the 14-inch rough cutout. The new A/C mounts right over the existing hole where the vent is now. Once you’ve established there are indeed conductors for the air conditioner present in the ceiling, the roof vent can be removed and the air conditioner installed.

Lighten the Load

Dear RV Doc, I'm fairly new to RVing and I bought a 31-foot Class A motorhome that has the HWH hydraulic leveling system. My question is: I live in upstate New York and the winters are pretty fierce here. I store my motorhome in a 35-foot carport (RV port) and would like to know if when storing my rig in the winter, should I have the jacks down to take the weight off the tires or is this not good for the leveling system? It’s just not possible to move the rig in the winter to change the tire position.

---Michael Lawrence, Fulton, NY

Michael, it is indeed permissible to extend the HWH hydraulic levelers during any period of non-use. This is another reason why I’m a fan of HWH. Just be sure to wipe down each leveler before retraction in case moisture, dirt or debris has gathered during the time it was under the carport. It’s always commendable to remove the weight on the tires during a storage period if possible, but don’t extend the levelers enough to raise the tires completely off the ground. Just take a little weight off of them and you’ll be fine. And be sure to check the level of the fluid in the reservoir too!

Oil of Choice

Dear Gary, what kind of hydraulic oil do you use in the slide-out pump?

---Joe Lucas, Fostoria, OH

Hey Joe, I do like those quick, to-the-point questions! Always use Automatic Transmission Fluid (ATF) in your slide-out pump. Most slideout and leveling jack pumps use ATF. Any other fluid, including hydraulic jack fluid, is not recommended by the manufacturer and could even damage the seals.

Send your troubleshooting questions to Gary at [email protected] and be sure to visit the RV Doctor on the web at www.rvdoctor.com. Questions of general interest will appear in a future issue. Due to the heavy volume of mail received, personal replies are not possible. Every effort is made to ensure the correctness of Gary’s responses; however, not all answers will apply in every instance. Some situations may mandate a visual inspection and further hands-on testing.

If you choose to follow these instructions, make sure that neither personal nor product safety will be compromised. If you do not feel comfortable performing a procedure, call your local RV service center to schedule an appointment.