Towing with the new Volvo XC90 is too easy?

[LoveToCamp]

Yes, and my Grand Cherokee says that, with the automatic leveling system, as weight-distributing hitch must be used. It likely stresses the system to put that much additional weight on the hitch.

[Padgett]

Actually what my OM says is a WDH is needed if the trailer weight exceeds 3500 lbs. Since I keep the load in my 2720Sl to a minimum, it should be below 3500.

[mecicon]

Originally Posted by Padgett

Actually what my OM says is a WDH is needed if the trailer weight exceeds 3500 lbs. Since I keep the load in my 2720Sl to a minimum, it should be below 3500.

Until you "pony up" and put that rig on a CAT scale (or similar variant) you just don't KNOW.

Your methods of 'divination' have not yet been confirmed.

[Padgett]

Agree. If you have to ask, best have a wDH.

[bheisser]

ok so i am curious i have a 2014 tacoma rated 6800Lbs with tow package,,,towed over 4000 miles this summer including the smokies in tennesee, and west virginia i77,,,never a hint of sway or issue,,,however i don't like the way it isnot level when loaded (a full truck bed ,plus loaded camper) .. and i do worry about the front tires staying down,,, so i added some firestone air rite bags
what will a wdh do that some air springs or such won't

thanks

[Bill]

Originally Posted by bheisser

... what will a wdh do that some air springs or such won't

Bob -

The only thing that air bags WILL do is level the tow vehicle. But that is a minor thing. Air bags WON'T do two important things.

1. They won't take any weight off the tow vehicle's rear suspension. The rear end of the tow vehicle (and that means springs, axles, bearings, wheels, tires, etc) is rated by the manufacturer to carry a certain amount of weight. This rating is called the GAWR-R (Gross Axle Weight Rating-Rear). If you overload the rear end, you risk damaging these components.
2. They won't move any weight onto the front axle. You said "i do worry about the front tires staying down", and you are right to worry about that. But air bags won't help. The front end is still unloaded.

The real purpose of a WDH is to move some weight off the rear end of the tow vehicle (where you have too much weight) and onto the front end of the tow vehicle (where you have too little weight). When it moves this weight from back to front, the tow vehicle becomes more level, of course. And that is good. But it is a side effect of a WDH's real purpose.

There are a couple good WDH articles in the TM Technical Library (aka TM Info You Won't Find Anywhere Else). You might read them.

Bill

[flipflop]

Ok, but if one has airbags and they're keeping the TV's rearend up high enough to eliminate the 'teeter-totter' effect isn't that pretty much the same effect as a WDH?

The tongue weight is being shifted back onto the trailer axle, the TV rear end isn't sagging to the point the front end is being lifted. And the airbags keep the rearend from fluctuating down in actual travel.

I put stiffer 3" lift coils and stronger rear shocks on the 4Runner (plus airbags) with the factory tow package to avoid the teeter-totter effect. Also a 2 3/4" rise ball mount. 15 lbs in the airbags keeps the rearend from sagging with initial hookup and bottoming on the road.

I went this route because I had problems before transitioning from onroad to offroad with a Reese like this http://www.pplmotorhomes.com/parts/c...FQa5wAodUQ0LEA

As soon as I started getting into dips, washes where the trailer was twisting one way, the truck twisting another that thing took a beating. Had to yank it, never used it again. Probably could have made a better choice in type of WDH this time around (one without bars) but decided since the 4Runner needed a lift for offroading may as well try to eliminate the WDH altogether.

The setup maybe is only 90% as effective as a WDH, but IMO easier to deal with, more versatility. The initial cost to upgrade the suspension was about $2000 so that is a glaring downside.

[BrucePerens]

Originally Posted by flipflop

Ok, but if one has airbags and they're keeping the TV's rearend up high enough to eliminate the 'teeter-totter' effect isn't that pretty much the same effect as a WDH?

No. The main purpose of the WDH is to move the center of pressure of the hitch weight forward of the tow vehicle's rear axle. Leveling your vehicle is a side-effect of that.

Consider the effect if you were stronger than you actually are, and if you were to walk up to the back of the vehicle and push down on the roof while pulling up on the bumper. You would torque the front of the vehicle down relative to the back, and put more weight on the front wheels than the rear ones. This is what the WDH does, but the torque is applied to the hitch receiver.

The effect is that the center of pressure of the trailer's hitch weight moves from the hitch ball forward. Hopefully somewhere forward of the rear axle, although I am dubious that some WDH's actually work that well.

A side effect is that you can distribute some weight to your trailer's axle, too. But IMO not more than 100 additional pounds.

[Padgett]

It is not easy to follow the forces of a WDH vs load levelers but the bottom line is a WDH uses torque to increase the force on he trailer axle and the front axle while reducing force at the hitch which translates to a reduction on the rear axle.

One of the least understood pieces is that a WDH is only a constant value when the TV and TM are on level ground. As as soon as you add an angle (dip or bump) the forces change.

OTOH load levelers or air lifts raise the rear by increasing the force on the rear axle. This does not change

In my specific case I did not want to add any load on the 3500 lb trailer axle.

[flipflop]

Originally Posted by BrucePerens

No. The main purpose of the WDH is to move the center of pressure of the hitch weight forward of the tow vehicle's rear axle. Leveling your vehicle is a side-effect of that.

Consider the effect if you were stronger than you actually are, and if you were to walk up to the back of the vehicle and push down on the roof while pulling up on the bumper. You would torque the front of the vehicle down relative to the back, and put more weight on the front wheels than the rear ones. This is what the WDH does, but the torque is applied to the hitch receiver.

The effect is that the center of pressure of the trailer's hitch weight moves from the hitch ball forward. Hopefully somewhere forward of the rear axle, although I am dubious that some WDH's actually work that well.

A side effect is that you can distribute some weight to your trailer's axle, too. But IMO not more than 100 additional pounds.

After I posted the above I started thinking about how a WDH is like a bowstring on a bow. Tighten the WDH and it distributes force to either end of the bow. Good analogy?

I realize my setup is not 'distributing' the tongue weight off of the TV's rear axle, it's only making it look like it's doing so.