Common Weight Distribution and Sway Control Questions

Weight Carrying: When towing a trailer with a standard ballmount, all of the trailer's tongue weight is transferred to the tow vehicle. Since the trailer hitch is attached to the vehicle frame, the additional weight in the rear will lower the back end of the vehicle while raising the front end. This means the rear axle will be handling not only the trailer tongue weight but additional load as weight is transferred from the front axle. Less weight on the front axle can lead to performance decreases in steering, traction, and stopping while also increasing trailer sway.

Weight Distributing: Weight distribution hitches add spring bars to the hitch system which are used to apply leverage between the tow vehicle and the trailer. This leverage transfers the load sitting on the rear of the vehicle to all the axles of the vehicle and trailer. With the trailer tongue and rear cargo load distributed between the axles, the vehicle is leveled off and performance is greatly increased. Weight distributing systems should be used any time the trailer weighs more than 50% of the vehicle weight.

Sizing: A weight distribution hitch will have two weight ratings, the gross trailer weight (GTW) and tongue weight (TW). The GTW capacity of the weight distribution system must exceed or match the loaded weight of the trailer. The TW rating listed on weight distributing hitches refers to trailer tongue weight plus the vehicle cargo weight behind the rear axle. It is important to match the weight distribution system tongue weight to your specific application. Using spring bars with a 1,000 lbs. TW capacity on a trailer with 400 lbs. of tongue weight while 100 lbs. of cargo is in the trunk (hitch weight = 500 lbs. total) can lead to erratic weight distributing performance. Looking at it the other way, if a weight distribution system has a 500 lbs. TW capacity with a 1,000 lbs. of weight, the system would be ineffective.

• Gross Trailer Weight (GTW) : The weight of the trailer fully loaded in its actual towing condition. GTW is measured by placing the fully loaded trailer on a vehicle scale.

• Tongue Weight (TW) : With weight distribution systems this includes the tongue weight of the trailer AND the cargo weight behind the rear axle in the vehicle. Trailer tongue weight is the downward force exerted on the hitch ball by the trailer coupler. In most cases, it is about 10 to 15 percent of the GTW.

Tongue Weight (for Weight Distribution) = trailer tongue weight + vehicle cargo load behind rear axle

Determining Trailer Tongue Weight: Measuring tongue weight on smaller trailers can be done using a bathroom scale and a box. On a level surface, place the coupler of the loaded trailer on the scale at normal towing height (Figure A). For heavier tongue weights, use the method diagrammed below (Figure B) or use a tongue weight scale.

Weight Distribution Components:

In addition to the class III, IV, or V trailer hitch on the vehicle, the weight distribution system is made up of the ballmount, spring bars (a.k.a. load bars or equalizing bars), and trailer mounted brackets. The ballmount is made up of two pieces. The shank, which slides into the trailer hitch and the ball platform which is referred to as the weight distribution head. The shank is available in different lengths with different drops and rises to allow for different trailer heights.

1. Hitch Assembly: The trailer hitch attaches to the frame underneath the vehicle and provides the 2" x 2" (or 2-1/2" x 2-1/2") receiver opening that the weight distribution shank slides into. Trailer hitches are divided up into different classes based on weight carrying capabilities. A trailer hitch needs to be classified as class III, IV, or V to be considered for a weight distribution system. A few Class III hitches are designed NOT to be used with a weight distribution system. Therefore, always check the weight capacity label that is on the trailer hitch. This sticker lists two capacities, Weight Carrying and Weight Distributing. If nothing is listed for weight distributing, then a weight distribution system can not be used.

2. Shank Assembly: The Weight Distributing Shank is the piece that slides into the hitch and provides an attachment point for the head. The shank is available in many different lengths, drops and rises. For easier and safer towing, it is necessary to have the trailer at a level height when it is hooked up to the hitch ball. The shank will allow you to do this. View our FAQ page for more information on choosing the correct ballmount height. You can also view all our available weight distributing shanks.

3. Head Assembly: The head unit holds the spring bars, provides a platform for the hitch ball, and attaches to the weight distributing shank. Weight distribution heads have a few different features to point out. The tilting mechanism, which fine tunes the weight distribution set up, is available in two different styles. The High Performance or Heavy Duty systems allow the tilt to be easily adjusted with serrated washers on the outside of the shank. The standard style systems use a pin with washers placed in between the head and the shank to control the tilt. Accessing the pin and washers can get quite tedious. However, this typically only has to be done upon initial set-up or if the trailer load changes enough to alter the coupler height.

The head can also have built-in platforms to allow for friction style sway control attachments. Many will offer only a right side attachment while some will have dual platforms which will be necessary for larger trailers (depending on the style of sway control used). The head is also made to accept different types of spring bars, round or trunnion. The round and trunnion terms refer to the end of the bars that attach to the weight distributing head. The round style bars slide up into the head and are held in place with clips. The trunnion style bars slide into the head from the side or back. The trunnion style of weight distribution is more heavy duty and can handle trailers of greater weight.

4. Spring Bar Assembly: As previously mentioned, there are two types of spring bars - round and trunnion - which refer to the end of the bars that attach to the weight distributing head. The round style bars slide up into the head and are held in place with clips. The trunnion style bars slide into the head from the side or back. Spring bars can also vary on the end opposite the trunnion or round bar end. The latest style from Draw-Tite, Hidden Hitch and Reese include built-in cams which are designed for use with Dual Cam Sway Control. The Draw-Tite, Hidden Hitch and Reese spring bars are also tapered on every side providing the ultimate in spring bar flex. The more the spring bar flexes, the more the weight distribution system will be working. When spring bars do not flex enough, the system can essentially turn off.

5. Chain and Bracket Assembly: Chain links are used to connect the spring bars to the trailer mounted brackets. The most common style is a snap-up uplift bracket. It lowers to grab the chain, then raises and snaps into position. The number of chain links is used to help determine the proper amount of tension to support the load. Space saving designs are also available that clamp to the trailer frame, or bolt to the side of the trailer frame.

Sway Control:

A popular accessory to the weight distribution system is the sway control. Trailer sway can be caused by cross winds, poor trailer loading (load too far back), or not enough spring bar tension. The use of a weight distributing hitch by itself will help improve trailer sway, but some additional products can help eliminate it. Trailer sway can be controlled with three different types of systems.

Independent friction controls have been around the longest. One side of the mechanism attaches to the trailer and the other to the weight distribution head. The steel bar with friction pad is used to slow down trailer sway. One slide bar friction control can be used for trailers up to 6,000 lbs. Anything over 6,000 lbs., and less than 10,000 lbs., will require 2 controls. Independent friction controls can also be used without a weight distribution system. Over or under tightening the sliding mechanism can render the system ineffective. [Part #3400]

Dependent sway controls are built in to weight distribution systems. They rely on the downward force of the spring bar to apply frictional resistance to brackets on the trailer tongue to combat trailer sway. This style is more consistent than the independent friction style, is easier to hook up, and over or under tightening is not a problem. This system is the only one approved for trailers with surge (hydraulic) brakes. [Part #49580, 49579, 49578, 66152, 66154, 66156, 66158]

Active sway controls also require a weight distribution system. An example of active sway controls is the Dual Cam System from Draw-Tite, Hidden Hitch and Reese which proactively and aggressively resist the start of sway by forcing the vehicle and trailer to ride in straight line. In tight turns the dual cam lifts the outside spring bar which increases towing performance by leaning the tow vehicle and trailer into the turn. The dual cam system can only work with weight distribution systems that have cams built into the spring bars. [Part #26000, 26002, and 26001]

Recent Weight Distribution Questions and Answers

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Question:

I have just upgraded to a hybrid travel trailer from a popup. My tow vehicle is a 2000 toyota 4-runner with a 5000lb towing capacity and 500lb hitch weight capacity. I have a 1100lb cargo capacity and a total combined gross weight of 9200lbs. The trailer is 3400lbs dry weight and 280lbs dry tongue weight. We have 2 dogs that travel in the back of the vehicle Mostly on or behind the rear axel. On reading your article above if I use a weight distributing hitch with the current setup I will exceed the hitch weight before loading the trailer, whereas if I just use sway control I will not exceed the maximum hitch weight. My calcuations are as follows: 280lbs tongue weight+90lbs for weight distributing hitch+140lbs of dog= 510 lbs hitch weight. Are my calculations correct.

asked by: Robert       last update: July 3, 2008

Question:

I recently purchased a new camper. I have owned many. The dealership hooked up the unit to my system. When pulling out onto the road something snapped and it was my sway control system. It had broken the small ball that conects it to my receiver completely off. The dealership apoligized and replaced my entire system. Receiver and all. A second time turning onto the road it snaps again This time bending the receiver and snapping my sway control in half. I noticed they tightened the sway control very tight instead of hand tight. We then just removed the sway system and towed it on home. The dealership is replacing the sway control, but I need to know how to keep this from happening again. Was it tightened too tight?

asked by: Wayne       last update: July 1, 2008

Question:

I have a 2008 2500HD Duramax Crew Cab short box. I also have a 96 camper for the truck. The camper is for an 8 bed, but is hauled in the 66 bed. Ive added airbags to handle the extra weight on the rear. Im wondering what type of hitch extension I can use to haul a 21 aluminum boat. Now doubt the truck will pull/handle the weight. However, what extension will handle the weight besides the costly torque lift dual tube setup?

asked by: Lee       last update: June 30, 2008

Question:

i have a 2000 silverado 1500 2wd and am towing a 20ft travel trailer at 4000 lbs. and less than 500 tw. i have heard that installing air helper springs will do the same thing as a weight distributing setup. which is the better setup and why.

asked by: Tim       last update: June 30, 2008

Question:

Can you tell me if there are any weight distribution hitches that fit the 1 1/4 class II hitch openings or are they all Class III

asked by: Jamie       last update: June 28, 2008

Question:

I just purchased a WPT 28 ft BR Work and Play toy hauler. I load 2 Harleys in the back about 1300 lbs. The total length of the trailer is 32 ft. The back area for the motorcycles is 10ft 6. This is my firdt trailer with the exception of a small 2 bike MC trailer. I purchased it from an individual who had used it only one time and it is a 2008 model. Empty trailer weight is 7562 lb. The brochure shows the hitch weight at 1133 lbs. GVWR is 11,292 and do not ever expect to be close to that weight. It came with a Reese WD hitch with the 2 equalizer bars marked at 1000 lbs. It has one Reese sway bar control. I have had some sway problems. It seems to me I may need a heavier duty hitch and more sway control. I pull it with a 3/4 ton crew cab 4 wheel drive 2008 super duty Ford Diesel. I am getting about a 21/2 to 3 swag in the rear bumper. What heavier duty hitch do you reccommend and what sway control? Is this too much swag and how can I control it?

asked by: Jim       last update: June 26, 2008

Question:

I have a 2003 GMC Yukon XL, 2 wheel drive, 5.7 L engine. I am towing a 2005 Four Winns 214 Funship deckboat 24 ft and trailer, weighing 6,250 lbs. I have just realized my trailer is more than my hitch is rated. What is the best solution to this. Is there a way to add a weight distribution system to my existing hitch, or is it better to replace the hitch with a new class IV hitch, rated at 10,000 lbs, towing capacity?

asked by: Perry       last update: June 25, 2008

Question:

I have an older 85 trailer which has a WD hitch and bars. On the truck I bought, the hitch set up is rated at 1000lbs TW, 10,000lbs GTW. The hitch does not fit into the reciever, only the first 1 goes in the pocket? Are there different sized recievers?

asked by: Jay       last update: June 24, 2008

Question:

I am seeking a 2003 30 Airstream Trailer. I have no idea what type of towing mechanism it will have, or what I should see it has on it for being towed. Safety is important to me, that and anti-sway. My average speed will probably be 62-55 in these gas-conscious days. Airstream tongue weight for this model is 730 lbs average. The factory empty weight is 7230. average Without me becoming a hitch expert, would you please tell me exactly what unit/units I should make certain are on the Airstream trailer. I do not have the tow vehicle yet. First the trailer, then the vehicle. I will insist that the used vehicle I get have a factory-installed tow package. What class package should that be? or What else do I need to know before purchasing this truck? How nice that you have a site where I can ask these questions and get answers that will be safe and correct, rather than surf the net and read all the myriad answers that leave me very confused.

asked by: Frances       last update: June 19, 2008

Question:

my trailer already has a bracket that is made right on the trailer my question is how do tighten the chains? they is no spot to hook the chain and then lift it to tighten it just a pocket to the chain into? do they make a system that will work with this?

asked by: Gary       last update: June 18, 2008

Question:

My father and I are wondering if we even need a weight distribution kit. We have a Ford E-350 16ft Cube truck. Were going to tow a 26 airstream. GTW is 4000lbs and tongue weight is around 500 lbs. With such a big truck designed for heavy load what kind of benefit would a weight distribution kit provide?

asked by: Eddie       last update: June 18, 2008

Question:

I have a 02 1500 v6 GMC pick up 8 foot bed 2wd my trailer weight is 7000 lbs my truck is rated to pull 5000 lbs if I get weight distribution bars will it bust the rating of the truck or do i need to buy a new truck????

asked by: Dave       last update: June 16, 2008

Question:

Have a 1988 Skyline with max loaded weight of 6000 lbs. truck is rated to pull 10,000, tongue weight rated at 1000 lbs. with weight distribution and 600 lbs without. I have sway bar which seems to work fine. The truck moves down 2 inches with trailer. Question: Do I need weight distributing hitch?

asked by: Paul       last update: June 5, 2008

Question:

I am getting ready to buy a trailer and I am confused about what kind of hitch set-up I should get. I have a 08 Toyota Tacoma with factory tow package. 6500 lbs tow limit. I am going to buy a 2009 forest river flagstaff micro lite 18 FBR. Its GVWR is 4500 lbs. the hitch wieght listed on the factory website is 107 lbs.

asked by: Greg       last update: June 4, 2008

Question:

Which weight distribution product would you recommend for a 1998 GMC Safari pulling a 15 toy hauler that weighs 3400 lbs.empty and 4400 loaded?

asked by: Walter       last update: June 2, 2008

Question:

I have a 24 foot enclosed Liberty trailer for my sand car, 2 quads, 2 motorcycles and all the other camping stuff we can fit in it. I try and keep most of the weight to the front of the trailer, but the trailer fish tails badly. I hate it and it scares me.

asked by: Ernie       last update: May 29, 2008

Question:

I have a travel trailer and have the weight distribution system, and friction sway controler. I want to know, is the sway controller suppose to help reduce trailer fish-tailing? Also, how tight should I get the sway controller?

asked by: Josh       last update: May 28, 2008

Question:

Am i supposed to take bars off when I exit the highway or should they work on sharp turns like right and left turns on side streets, because my bars have fell out of sockets from ball attachment

asked by: Al       last update: May 27, 2008

Question:

I have a 91 GMC 1500 Suburban. My Trailer weight 19camper is 5,000lb What weight distribution system do you recommend for my application?

asked by: Paul       last update: May 2, 2008

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