Dumb question about leveling

Regarding porpoising:

With my Chevy 1500HD Crew Cab 6.5 foot bed I had a little porpoising.

With my GMC 2500HD Crew Cab 8 foot bed I do not.

The Chevy is 20 feet long. The GMC is 22 feet long. I am not sure what the wheelbase is, but the GMC is certainly longer.

My point is, it has been my experience that longer is better, at least in regard to porpoising.

You probably do not want trucks as big as I do. But if I were comparing two different tow vehicles, wheel base might become the tie breaker.

I do not use WD hitch or sway bars, because they are not necessary for me.

The irony is I _think_ the wheelbase on my Sienna is the same length as the Expy (~119" IIRC) -- so I'm betting in this case it's the nice, stiff springs meant to support a heavy load.

In any case, it's a pleasant surprise.

Depending on which of my two trucks I use, the wheel base is either 133 or 143 inches.

I can tell the difference in porpoising between 133 and 143.

A WD hitch would very likely accomplish the same result on a shorter wheelbase vehicle.

Thanks for that detailed report - that's awesome! I would love to follow behind!!

[ELM-JLM]

This is a very good explaination of WDH versus Air Shocks or Air Bags!

Airbags are great, but they are definitely not a replacement for a Weight-Distribution Hitch. A WDH has 2 primary purposes, as well as several additional benefits.

A WDH will raise up the back of the tow vehicle, and reduces some of the sag caused by the trailer’s tongue weight. And I think this is what the OP is referring to in his comparison to air bags. Both will raise up the rear end of the truck.

But the way a WDH raises up the rear of the truck is key – it uses torsion to shift a percentage of the tongue weight to the front axle of the tow vehicle. This is the key difference between a WDH and airbags. Without shifting some of the tongue weight onto the front axle, you‘re likely to have problems in a panic stop or other emergency maneuver. When you brake hard, the weight of the trailer shifts forward and pushes down on the hitch ball even harder than normal, which causes the truck to get light on the front wheels. When that happens, you can lose steering and a big part of your braking capacity. A WDH resists the trailer’s nose-dive, and keeps more of that tongue weight transferred forward.

By using Airbags instead of a WDH, in the same panic stop as above, the trailer weight will shift forward, pushing down on the hitch ball. The hitch in turn, will push down on the rear of the truck. Since the airbags are resisting that downward force (at the axle), they become a pivot point, and the front end can get light very quickly.

In addition to the 2 primary purposes described above (shifting weight to the front axle & reducing sag), a WDH also introduces more stability when encountering cross winds, especially if you use a sway control device with the WDH. Also, most modern trucks come with hitches that are rated lower when not using a WDH, and higher when using one. Some peope ignore those ratings, but that's a whole other conversation.

According to the TM factory, sway control is not needed. Maybe if you have the smallest possible TV it would be helpful.

There is a downside to the WDH. It not only shifts weight onto the TV front axle, it also shifts weight onto the TM axle. My TM axle was 3380 the one time I weighed it. I really do not want to shift weight back there.

My 1500HD was fine with no WDH until I loaded 2 motorcycles in the bed. Then it sagged too much. For this situation rear airbags would probably have been a better choice than WDH.

My solution was to add a second larger truck, my 2500HD.