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Retirement on the road
Don't give up on your old truck when it's time to retire!

by Bruce Mallinson

Several months ago, we discussed what it takes to convert a Class 8 truck into a recreational vehicle hauler. As it turned out many of the readers of this magazine are approaching the retirement age and judging from the number of responses to previous articles on this subject, many are contemplating what to do when they retire.

First, let's list the advantages of using a Class 8 truck to pull a 20,000-pound fifth-wheel recreational trailer. Yes, these trailers do indeed weigh 20,000 lbs. when loaded, and some RV owners will pull a 5,000-lb. automobile, SUV or boat behind the fifth wheel (this is not legal in all states).


  1. You already own the truck. A new one-ton dually diesel pickup now costs $38,000 and cannot legally pull much more than 12,000 lbs.;
  2. A medium-duty truck converted to pull an RV costs between $85,000 and $108,000; and
  3. Your Class 8 truck will last the rest of your life, figuring you are towing an RV about 15,000 miles per year.
  4. Class 8 14-liter engines will get the same fuel mileage as a medium duty 8-liter engine. Needless to say, the smaller 8-liter engine will not run with the 14 liter in the mountains. Yes, it's a horsepower war in the RV industry, as nobody wants to be passed - especially by their friends. Keep in mind a fifth-wheel camper or a motor home, to a lady, is a home. To a man, it's a street rod you can sleep in.
  5. Wind and rain do not push a big truck across the highway as they do a pickup.
  6. There is enough space behind the bunk to haul a motorcycle, golf cart or quad.
  7. Use only one fuel tank for diesel fuel. The other tank can be used to carry water. The average recreational vehicle will only carry about 75 gallons of water, enough for only five days. The extra 120 gallons in the converted fuel tank is a lifesaver. Pur chase the same water pump that's in your RV and mount it near the water tank in the truck. This pump and a white water hose will easily fill your RV water tank. If the pump in the RV ever fails, just unhook the pump on the truck and install it in the RV. Nothing is worse than being without water.
  8. Most RVs can carry about 2,500 lbs. additional weight. With a Class 8 truck, you can carry as much as you desire. You'll never be able to overload the truck.
  9. When towing with a pickup truck, the wagon will control the horse. With a big truck, the horse always controls the wagon.
  10. The Class 8 truck has much better brakes and visibility. If you are in an accident, it's very unlikely that the RV would run up over the frame rails and crush the cab from behind. Sit in a pickup truck, look in the rear view mirror and notice how the fifth-wheel trailer dwarfs the pickup.

I'm sure there are many more advantages. However, we need to talk about ping tanks in this issue. A ping tank is an auxiliary air tank mounted right above the rear air bags. The airlines must be routed into the ping tanks, then into the air bags with one and one-half inch air brake plastic tubing. Whenever the rear tires hit a bump the air will be forced into the tanks first, then, secondly, the air bag will take the shock.

The auxiliary air tank will drastically soften the rear suspension. Will the ping tank have the same effect on a working truck with 34,000 lbs. on the deck? It should, so someone needs to try this setup and advise me as to how much softer the ride becomes. Remember the ping tank is an accumulator tank and must be mounted near the air bags to work properly.

Use an air tank that is made for your truck. I cut mine in half then welded a quarter-inch steel plate in the center and joined the two halves together. I now have two, two and one-half-gallon air tanks made from one tank. The average air tank holds between five and seven gallons. Some people feel it's not necessary to divide the air tank and they may be right, but the medium-duty trucks equipped with ping tanks have two. One for each air bag. That's why I divided my tank into two. Instead of calling the bags air bags we should refer to them as air springs. However, to me a spring is steel and the air bag is rubber. So, to me it's still an air bag.

Written by Bruce Mallinson of Diesel Injection of Pittsburgh (PA). You can reach him at