WDH Question

[Bill]

RedHawk posted

I'm not sure if I believe that leveling the truck does not put at least put most of the weight back on the front axle.

and

Here's my analogy.......take a 200 lb beam, attach a pivot point 3/4's of the way back, (like your rear axle). Put your head under the front of the beam. I'll lift up on the rear of the beam. Tell me if you feel any pressure.

John –

Regarding the question of whether air bags transfer weight back onto the front end. Your analogy doesn’t quite work, because you are lifting at the rear of the beam, while air bags lift at the pivot point. And I contend that if you lift the beam an inch or so at the pivot point, the weight on my head will not increase. However, we can step away from theoretical analogies, because your description suggests an easily conducted real-world experiment. It would be great if you would run this, and post the results.

Get yourself a good sturdy plank. The length isn’t critical, but let’s assume 10 feet, since the wheelbase of many tow vehicles is about 10 feet.

Put a bathroom scale on your garage floor, and put one end of the plank on it. This represents the front axle of the tow vehicle. Ten feet away, put the other end of the plank on a wood block. The block represents the rear axle of the tow vehicle. Get someone to watch the scale as you lift the rear end of the plank two inches off the wood block. Your contention is that the scale reading will go up, because weight is transferred to the front. My contention is that the reading will not change. What is your finding? Does weight transfer?

OK, that experiment represented the effect of bags on the tow vehicle only. Now let’s repeat the experiment, and add the TM into the equation.

Get rid of the 10-foot plank, and substitute a 12-foot plank. Again, put one end on the scale, and the other end on the block. The block is still 10 feet away from the scale, so now there is 2 feet of plank overhanging the block. Read the scale and write down the reading. Now put a couple bricks on the overhanging end of the plank – this represents the TM’s hitch weight coming down on the hitch ball, which is, of course, a couple feet behind the rear axle. Read the scale again. I think you will agree that the reading on the scale will be reduced, because of the teeter-totter effect around the pivot point (the rear axle). Again, have someone watch the scale reading as you put your hands (the air bags) under the plank at the pivot point, and lift the plank two inches. Your contention is that as you lift, some weight will be transferred back onto the scale, and the reading will go up. My contention is that the weight on the scale will not change. What is your finding? Does weight transfer simply because your air bags lifted the plank two inches above the pivot point?

Two things come out of this last experiment. First, putting the bricks on the end of the plank reduces the weight on the front axle. As was pointed out in an earlier post, the front axle does most of the braking and all of the steering, and the capability for both is reduced by unweighting the front end. Dangerous! Second, when you put the bricks on the end of the plank, the weight on the front wheels was reduced. This means that the rear axle is now carrying the full weight of the bricks, plus whatever weight was removed from the front end. This can be tough on the rear suspension components - shocks, tires, etc.

Third – if, as I contend, adding air bags to lift the plank off the wood block does not put weight back on the front wheels, then the airbag has accomplished nothing in terms of unloading the rear end of the tow vehicle, or curing the dangerous unweighting of the front end.

Bill

[Mr. Adventure]

Let me know if you need me to go research this some more in the Jefferson library.

[ThePair]

The only way raising a pivot will transfer weight is the substantially alter the angle of the plane of the vehicle with respect to the earth, so that the effective center of gravity of the vehicle shifts, and thus the torque around that pivot point.

In other words, I doubt a 2" rise will make any kind of real world measurable difference. On paper there could be a miniscule, calculable difference, but it's not going to translate into a real world difference.

Thanks all, I was just being a smarty pants and trying to be funny. Fail.
I'll certainly use the WDH for now, it's not worth the risk for the small amount of work involved hooking it up.

BUT....I really like Bill's idea. I think I will try it next week when I have some time off. Just to help my slow brain understand a little better.

[mecicon]

Originally Posted by Redhawk

If it helps, I use a Reese Pro WDH with 1200lb bars and my 2619 has a swing tongue. eTrailer has them on line along with a wide selection of others that I suspect will work as Bill says.....
I also use air bags to level the truck when i take my ATV along in the bed of the Tundra.

I'm not sure if I believe that leveling the truck does not put at least put most of the weight back on the front axle. Seems like it has to. It feels like it does when I drive it, and I use one less link on the WDH hitch when I use the 2 together. After leveling the truck with the air bags and ATV in the bed. There is only a small amount of sag when I put the TM on the WDH hitch. The tension on the bars is very light. Maybe I have too much air in the bags, but it seems silly to me to let air out just so I can relevel it with the WDH. I admit, I don't have a complete understanding how the 2 systems interact with each other.....so go easy on me.

Okay, this one:
http://www.etrailer.com/Weight-Distr...ies/49568.html

or this one:
http://www.etrailer.com/Weight-Distr...ies/49585.html

Remember I have a swing away, I don't want to pay someone to do this.

Originally Posted by Redhawk

If it helps, I use a Reese Pro WDH with 1200lb bars and my 2619 has a swing tongue. eTrailer has them on line along with a wide selection of others that I suspect will work as Bill says.....
I also use air bags to level the truck when i take my ATV along in the bed of the Tundra.

I'm not sure if I believe that leveling the truck does not put at least put most of the weight back on the front axle. Seems like it has to. It feels like it does when I drive it, and I use one less link on the WDH hitch when I use the 2 together. After leveling the truck with the air bags and ATV in the bed. There is only a small amount of sag when I put the TM on the WDH hitch. The tension on the bars is very light. Maybe I have too much air in the bags, but it seems silly to me to let air out just so I can relevel it with the WDH. I admit, I don't have a complete understanding how the 2 systems interact with each other.....so go easy on me.

1200 lb. are quite heavy for a 500 or so lb. tongue weight. Even though the tension on the bars feels very light when you hook up on level ground, the bars will exert a lot more force when going through a dip, like out of gas station or such. 800 lb. bars are more springy, and would not exert the same forces, and probably give you a much better ride.

According to the information that I have found, 800 lb. bars are good for tongue weights between 400 and 800 lbs, while the 1200 lb. bars are good for 600 to 1200 lbs.

Yeah, I didn't know a lot oabout WDH's when I purchased the TM and WDH, but I did ask if the 1200 lb ones weren't a bit too much, the dealer said that was the one they found to work the best. Maybe....but with the air bags I have, I'd prefer to have the 800 lb spring bars. Checking the prices, they are dang near the same price I paid for the whole WDH setup!!
I'll keep my eye out for a pair. Thanks for the info and post.

That said though....I've had no issues, porposing or anything else with the 1200 lb bars. They have served me well. With the air bags, I connect the bars on one less link then I used too...

I have been back and forth between 800 and 1200 lb. bars with my current 700 lb. weight trailer. I started with 800 lb. bars, but it seemed that I really had to tilt the head back so far, plus I had a rub problem with the Reese Dual Cam and my trunnion bars. I went to 1200 lb. bars, and got plenty of lift, but the bars still rubbed. After help from a knowledgeable forum member at RV.net, and several calls to Reese, I went to a 1" raised ball to alleviate some of the rub problem. The 1200 lb. bars felt really stiff, so I retried the 800 lb. bars with the 1" raised ball. I now have the ball mount platform tilted all of the way back, but it puts all of the lost weight (and then a little) back on the front axle, and it feels much better going down the road that the 1200 lb. bars.......which are now laying unused in my garage.

[Wavery]

I have an "Equalizer" 600# WDH. When I use it, it feels ideal for the rig. However, it just isn't worth the aggravation and strain on my back to use it.

If I were going to go on a long trip with lots of mountain driving or unknown weather conditions, I would use it. With the WB (and weight) on my truck, there is no issue with front wheel control on dry pavement.

[Keith Wire]

Originally Posted by harveyrv

I have an "Equalizer" 600# WDH. When I use it, it feels ideal for the rig. However, it just isn't worth the aggravation and strain on my back to use it.

Wayne, what do you mean "strain on my back"? Just carrying the pieces or hooking up the bars?

Keith