Tongue weight question

[airstreamdav]

Looking at the Audi Q7 as a TV. Q7 doc says hitch weight not to exceed 770 lbs. 25 ft Serenity shows 835 lbs. Assuming I don't want to exceed specs, does that pretty much eliminate the Q7? Thank you.

[Bill M.]

I would suspect the actual loaded tw would be even higher than the spec.

[Wesair]

Besides tongue weight be sure to check the other specs too (such as GVWR). My TV can handle the tongue weight and pull 9400 lbs but with a trailer attached I don't have much capacity to carry things in the bed of the truck (about 200 lbs). Leaving my wife at home isn't a viable option so we are just going to have to pack light.

[airstreamdav]

Good point. I looked at the Q7 specs and the only thing that worries me was the 770lbs hitch rating. As is mentioned, the realistic tongue weight will probably be at or a little over 1000 lbs - way over the Q7 spec. However, is this were weight distribution systems come into play? I read the weight distribution systems can reduce hitch weight by 20% or so - that would bring the hitch weight very close to the Q7 spec.

[AWCHIEF]

Airstream seems to underestimate their actual real world tongue weights by a significant amount.

[A W Warn]

Originally Posted by airstreamdav

Good point. I looked at the Q7 specs and the only thing that worries me was the 770lbs hitch rating. As is mentioned, the realistic tongue weight will probably be at or a little over 1000 lbs - way over the Q7 spec. However, is this were weight distribution systems come into play? I read the weight distribution systems can reduce hitch weight by 20% or so - that would bring the hitch weight very close to the Q7 spec.

Weight distribution does not change the weight bearing on the hitch. It re-distributes weight away from the rear axle, to both the trailer's and tow vehicle's front axles.

Some vehicle manufacturers allow more vertical load on the hitch when weight distribution is used. But, not all of manufacturers do.

add edit:
don't forget that you will be adding the weight of the hitch insert with the hitch ball and the sway control to the tongue weight of the trailer. The sum of these weights are the load you should use to calculate if your hitch receiver on the tow vehicle is adequate.

[airstreamdav]

Ok. So if the hitch weight on the vehicle is 1000 lbs, it will still be 1000 lbs after adding a weight distribution hitch?

[TG Twinkie]

Yes. WD systems only distribute the weight more evenly between the TV's front and rear axles and the trailer axles.
If it removed tongue weight it would defy gravity and be called a weight elimination system.

[Ohiobrits]

Airstreamdav,

Check out the thread linked below for lots of information on the Touareg, Cayenne and Q7 (similar vehicles) and some discussion on your tongue weight question. There are hundreds and hundreds of people happily towing Airstreams with these vehicles.

Good luck.

http://www.airforums.com/forums/f463...rs-134917.html

[Adventure.AS]

Originally Posted by airstreamdav

Ok. So if the hitch weight on the vehicle is 1000 lbs, it will still be 1000 lbs after adding a weight distribution hitch?

The principles of weight distribution systems are not intuitive.

Think of it as if you had to carry 100 lbs by hand. If you had one bucket all of the downward force would be on your one arm and shoulder and would be stressful on those joints and you would likely be left leaning to one side. However if you carried two buckets, one in each hand with 50 lbs in each the load would be balanced, total weight carried would be the same, but the downward force and stress on each shoulder would be half as much. WD bars work in a similar manner.

As you couple your trailer to the tow vehicle by lowering the a-frame tongue jack, the weight of the tongue is gradually transferred from the jack to the hitch ball until all of the weight is on the hitch and the jack foot is off the ground. You will see that the rear of the TV goes down under this load and the front of the TV goes up.

Then you lock the coupler on the ball and using the jack lift the tongue of the trailer and the rear of your TV enough to easily engage your WD bars. Next, lower the jack and if properly set up the WD system will transfer some of the tongue weight from the ball hitch to the TV's front and rear axles. You can see the evidence of this at work when you measure how much the front of your TV lowers and the rear of your TV raises when applying the WD. (Hopefully now your TV is close to the stance it had before hooking on your trailer and not sagging in the rear or nose down in the front. If the ball was set at the correct height the trailer should be level too.)

Although the tongue weight is actually unchanged the effect is that the downward force (weight) on the hitch is reduced by the action of lever system of the WD bars which "virtually" move the weight off of the hitch ball to the axles of the TV using torque. The weight didn't disappear it was just distributed by the use of the simple, yet effective lever.

You may need to have your hitch receiver strengthened to be able to withstand the torque of the WD system. For example, in my system a steel tube was welded from the inside end of the receiver to a steel cross member near the axle. This helps to distribute the torque from the bumper mount to the frame more effectively.

[dznf0g]

Originally Posted by TG Twinkie

Yes. WD systems only distribute the weight more evenly between the TV's front and rear axles and the trailer axles.
If it removed tongue weight it would defy gravity and be called a weight elimination system.

Well, sorta. Weight is in fact "removed" or "moved" or "relocated. You can't add weight to the front axle and AS axle without removing it somewhere else.

Weight = the effect of gravity on mass.

So when you "cheat" the physics of gravity by applying a force on a lever (spring bars), you re-"move" weight and place it elsewhere. Mass doesn't change.

Another way. A full wheelbarrow sitting on the pavement has weight on two legs and one wheel. Then you pick up the handles and the legs are off the ground, they have zero weight on them. Mass is still there, but the weight has now moved to an increase in on the wheel, on the handles and through you to the ground.

[airstreamdav]

This all has been very helpful. Thank you.

[ghaynes755]

Get hold of Andy at Can-AM RV (www.canamrv.ca). Bit of a drive but they are the experts on setting up cars and Airstreams. I'd bet they can give you some straight advice.

[airstreamdav]

Thank you