I'm still pondering whether or not our Outback can safely tow a little heavier egg than our 13' Scamp. The Subaru manual limit is 3,000# for the trailer, which opens up several possibilities if we're careful with loading. However, the tongue weight limit is only 200#. I've been looking at light duty weight distribution hitches as a possible solution. So here's my question for all the weights and moments experts. Just in round numbers, let's say I have a trailer with a 200# tongue weight. I hook it up and measure the sag at the rear of the TV. Now, let's pretend I hook up a trailer with a 300# tongue weight, but with a WDH adjusted to give the same amount of sag as when the 200# tongue was applied. Have I complied with the manual's limit of 200# tongue weight?
For a bonus question, I'm aware that there are guidelines for hitch weight as a percentage of total trailer weight. When using a WDH, what number does one use? The actual weight of the tongue as measured with a scale, or the effective weight that results from the adjustment described above?
Parker
Full Version: Weight Distribution Hitch
FiberglassRV > All About Our Unique Little Molded Fiberglass Trailers > Towing -- Tow Vehicles, Hitches, Sway, Tires, Brakes
Short answer, no.
Long answer, Kind-of.
The specs you are quoting for the are for non-WD towing. Once a WD hitch is employed, tongue weight limitation is a function of the lesser of either the receiver's rating or the vehicle's payload capacity. There is no longer dead weight hanging off the rear bumper if the hitch is properly adjusted so the weight is transfered to the front wheels and the trailer.
So, adding a WDH solves one problem, but other problems remain.
First: You are limited by the weight limit of the hitch receiver.
Is it an OEM hitch or an after market hitch?
Do you have a Class II or Class III hitch on the Subaru?
What is the weight limit of the hitch?
That should be considered a firm limit not to be exceeded
Second: You are limited by the weight limits of the front and rear axels, wheels, and tires.
What are the front and rear axle weight limits?
What are the front and rear axle weights when the Subaru is loaded to go camping but trailer is not attached?
What are the axle weights when loaded and towing the trailer with WDH?
Are your wheels and tires up to the load they will carry. Typically fancy wheels are light weights only. Tires have weight limits molded into them
All of these also, should be considered firm limits not to be exceeded.
Third: Other things to consider.
Does the Subaru discuss using a WDH? Some vehicles prohibit using a WDH.
Vehicle frame or lack there-of
spring and shock limits
When using a WDH 10% to 15% is still the recommended actual weight of the tongue. Tongue weight using a WDH would be the effective weight. Use the actual weight of the tongue for everything else.
Long answer, Kind-of.
The specs you are quoting for the are for non-WD towing. Once a WD hitch is employed, tongue weight limitation is a function of the lesser of either the receiver's rating or the vehicle's payload capacity. There is no longer dead weight hanging off the rear bumper if the hitch is properly adjusted so the weight is transfered to the front wheels and the trailer.
So, adding a WDH solves one problem, but other problems remain.
First: You are limited by the weight limit of the hitch receiver.
Is it an OEM hitch or an after market hitch?
Do you have a Class II or Class III hitch on the Subaru?
What is the weight limit of the hitch?
That should be considered a firm limit not to be exceeded
Second: You are limited by the weight limits of the front and rear axels, wheels, and tires.
What are the front and rear axle weight limits?
What are the front and rear axle weights when the Subaru is loaded to go camping but trailer is not attached?
What are the axle weights when loaded and towing the trailer with WDH?
Are your wheels and tires up to the load they will carry. Typically fancy wheels are light weights only. Tires have weight limits molded into them
All of these also, should be considered firm limits not to be exceeded.
Third: Other things to consider.
Does the Subaru discuss using a WDH? Some vehicles prohibit using a WDH.
Vehicle frame or lack there-of
spring and shock limits
When using a WDH 10% to 15% is still the recommended actual weight of the tongue. Tongue weight using a WDH would be the effective weight. Use the actual weight of the tongue for everything else.
QUOTE (Curtis F. @ Sep 16 2009, 11:23 PM) 
Short answer, no.
Long answer, Kind-of.
The specs you are quoting for the are for non-WD towing. Once a WD hitch is employed, tongue weight limitation is a function of the lesser of either the receiver's rating or the vehicle's payload capacity. There is no longer dead weight hanging off the rear bumper if the hitch is properly adjusted so the weight is transfered to the front wheels and the trailer.
So, adding a WDH solves one problem, but other problems remain.
First: You are limited by the weight limit of the hitch receiver.
Second: You are limited by the weight limits of the front and rear axels, wheels, and tires.
Third: Other things to consider.
Does the Subaru discuss using a WDH? Some vehicles prohibit using a WDH.
When using a WDH 10% to 15% is still the recommended actual weight of the tongue. Tongue weight using a WDH would be the effective weight. Use the actual weight of the tongue for everything else.
Long answer, Kind-of.
The specs you are quoting for the are for non-WD towing. Once a WD hitch is employed, tongue weight limitation is a function of the lesser of either the receiver's rating or the vehicle's payload capacity. There is no longer dead weight hanging off the rear bumper if the hitch is properly adjusted so the weight is transfered to the front wheels and the trailer.
So, adding a WDH solves one problem, but other problems remain.
First: You are limited by the weight limit of the hitch receiver.
Second: You are limited by the weight limits of the front and rear axels, wheels, and tires.
Third: Other things to consider.
Does the Subaru discuss using a WDH? Some vehicles prohibit using a WDH.
When using a WDH 10% to 15% is still the recommended actual weight of the tongue. Tongue weight using a WDH would be the effective weight. Use the actual weight of the tongue for everything else.
Curtis,
Thanks for your detailed response. I can answer at least some of your questions, all of which I appreciate.
We currently have only the Class I OEM Subaru hitch. I know this is not adequate. Reese makes Class II and III hitches for the car which well exceed the factory towing limits (which I know are not to be exceeded). These can be used with a WDH.
The manual states to not use a WDH with the factory hitch, but does not comment on the use of aftermarket hitches. I have sent two info requests to Reese seeking their opinions on this; still waiting for a relpy. I am concerned that the Subaru is a uni-body, and I don't know how much torque can be applied to the rear hitch mounts to transfer weight away from the hitch area. This may still be a show stopper.
I'm only trying to distribute something like 50-75 pounds of hitch weight; not trying to pull a Bigfoot! I would certainly check all the numbers you've listed, but my assumption until I learn otherwise is that if the rear tires and suspension are adequate for 200 pounds of tongue weight, I could surely distribute the additional 50# (plus weight of the WDH) between the trailer and the front wheels with a WDH.
Just to clarify, do you mean that after the WDH is adjusted, I should still have 10+% downforce on the hitch? That gets me back to exceeding the original 200# weight limit. When talking with Scamp about all this, their approach was to simply load the trailer to get the tongue weight below 200# and then go with a sway bar. Guesstimating a 2500# trailer and 200# hitch weight, that would give us 8%. Is that considered sufficient if some sort of sway control is used?
Thanks again!
Parker
Different Owner's Manuals treat the towing subject differently. I tow with a 2003 Honda Odyssey LX
The factory installed Hitch receiver has a label that claims a limit of 3500 pound total trailer weight and 350 pound hitch weight. The Honda manual does not state a specific hitch weight limit; just the 10% of trailer weight stated above.
QUOTE (ODYSSEY 2003 Owner's Manual)
Towing Equipment and Accessories
Weight Distributing Hitch
If the total trailer weight is more than 1,850 Lbs (840 Kg), you must also use a weight-distributing hitch. This device transfers weight from the vehicle's rear wheels to the front wheels, and to the trailer's wheels. Carefully follow the hitch maker's instructions for proper installation and adjustment.
Sway Control
If the total trailer weight exceeds 2,000 Lbs (900 Kg), you should install a sway control device to minimize swaying that can occur in crosswinds and in normal and emergency driving maneuvers. Your trailer maker can tell you what kind of sway control you need and how to install it.
Trailer Brakes
Honda recommends that any trailer having a total weight of 1,000 Lbs (450 Kg) or more be equipped with its own electric or surge-type brakes.
Total trailer weight:
The maximum weight you can tow depends on several factors. See chart below for limits for your towing situation. Towing a load that is too heavy can seriously affect your handling and performance.
Tongue Load:
The weight that the tongue of a fully loaded trailer puts on the hitch should be approximately 10 percent of the trailer weight. Too little tongue load can make the trailer unstable and cause it to sway. Too much tongue load reduces front-tire traction and steering control.
Maximum Total Trailer Weight:
Number of Occupants-----------------------------------Equipped with transmission cooler
Including Driver*-----------------------------------------and power steering fluid cooler
-----2-------------------------------------------------------------3,500 Lbs (1,580 Kg)
-----3-------------------------------------------------------------3,350 Lbs (1,520 Kg)
-----4-------------------------------------------------------------3,200 Lbs (1,450 Kg)
-----5-------------------------------------------------------------3,050 Lbs (1,380 Kg)
-----6-------------------------------------------------------------2,900 Lbs (1,310 Kg)
-----7---------------------------------------------------------------650 Lbs (295 Kg)**
*Based on 150 Lbs (70 Kg) per occupant
**Weight limited to avoid exceeding rear GAWR
Gross Vehicle Weight Rating (GVWR)
The maximum allowable weight of the vehicle, all occupants, all cargo, and the tongue load is:
5,665 Lbs (2,570 Kg)
Gross Axle Weight Rating (GAWR)
The maximum allowable weights on the vehicle axles are:
2,833 Lbs (1,285 Kg) on the front axle, and
2,845 Lbs (1,290 Kg) on the rear axle.
Gross Combined Weight Rating (GCWR)
The maximum allowable weight of the fully loaded vehicle and trailer is:
8,265 Lbs (3,750 Kg) with the proper hitch and fluid coolers.
Weight Distributing Hitch
If the total trailer weight is more than 1,850 Lbs (840 Kg), you must also use a weight-distributing hitch. This device transfers weight from the vehicle's rear wheels to the front wheels, and to the trailer's wheels. Carefully follow the hitch maker's instructions for proper installation and adjustment.
Sway Control
If the total trailer weight exceeds 2,000 Lbs (900 Kg), you should install a sway control device to minimize swaying that can occur in crosswinds and in normal and emergency driving maneuvers. Your trailer maker can tell you what kind of sway control you need and how to install it.
Trailer Brakes
Honda recommends that any trailer having a total weight of 1,000 Lbs (450 Kg) or more be equipped with its own electric or surge-type brakes.
Total trailer weight:
The maximum weight you can tow depends on several factors. See chart below for limits for your towing situation. Towing a load that is too heavy can seriously affect your handling and performance.
Tongue Load:
The weight that the tongue of a fully loaded trailer puts on the hitch should be approximately 10 percent of the trailer weight. Too little tongue load can make the trailer unstable and cause it to sway. Too much tongue load reduces front-tire traction and steering control.
Maximum Total Trailer Weight:
Number of Occupants-----------------------------------Equipped with transmission cooler
Including Driver*-----------------------------------------and power steering fluid cooler
-----2-------------------------------------------------------------3,500 Lbs (1,580 Kg)
-----3-------------------------------------------------------------3,350 Lbs (1,520 Kg)
-----4-------------------------------------------------------------3,200 Lbs (1,450 Kg)
-----5-------------------------------------------------------------3,050 Lbs (1,380 Kg)
-----6-------------------------------------------------------------2,900 Lbs (1,310 Kg)
-----7---------------------------------------------------------------650 Lbs (295 Kg)**
*Based on 150 Lbs (70 Kg) per occupant
**Weight limited to avoid exceeding rear GAWR
Gross Vehicle Weight Rating (GVWR)
The maximum allowable weight of the vehicle, all occupants, all cargo, and the tongue load is:
5,665 Lbs (2,570 Kg)
Gross Axle Weight Rating (GAWR)
The maximum allowable weights on the vehicle axles are:
2,833 Lbs (1,285 Kg) on the front axle, and
2,845 Lbs (1,290 Kg) on the rear axle.
Gross Combined Weight Rating (GCWR)
The maximum allowable weight of the fully loaded vehicle and trailer is:
8,265 Lbs (3,750 Kg) with the proper hitch and fluid coolers.
The factory installed Hitch receiver has a label that claims a limit of 3500 pound total trailer weight and 350 pound hitch weight. The Honda manual does not state a specific hitch weight limit; just the 10% of trailer weight stated above.
QUOTE (Parker Buckley @ Sep 17 2009, 10:12 AM)
Just to clarify, do you mean that after the WDH is adjusted, I should still have 10+% downforce on the hitch? That gets me back to exceeding the original 200# weight limit. When talking with Scamp about all this, their approach was to simply load the trailer to get the tongue weight below 200# and then go with a sway bar. Guesstimating a 2500# trailer and 200# hitch weight, that would give us 8%. Is that considered sufficient if some sort of sway control is used?
Thanks again!
Parker
Thanks again!
Parker
Arrrgggghh. Wrote a excellent reply 2 hours ago and thought It posted.
Shorter not so eloquent reply.
No. After the WDH is adjusted you are not concerned with either static or effective tongue weight relative to a tongue weight limit.
You will need to be aware that the set up will be susceptible to sway. You should consider a WDH that incorporates sway control. That excludes the little friction bars that can be separately added. Lot's of people use them, I don't like them because of the physics of the mechanical braking action when turning. Also loss of effectiveness in rain.
The Reese hitch receivers look like they will address your problem as long as the above vehicle weight limits are not exceeded. Install, load it up, take it to a truck scale and have them weigh you as a triple if possible. Weighing as a triple normally means the weigh the tractor, 1st trailer, 2nd trailer. You want to weigh each of the axles on a separate weight pad. WDH is going to put your headlights back on the road rather than up in the trees.
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