What is the right way to adjust sway bars

[Inland RV Center, In]

Originally Posted by toastie

Thanks Overlander and also Andy, so with my system, if I get some deflection it is doing some good?, what would happen if I don't use the system at all, you must understand I'm new to this.....thanks again

If you don't use a load equalizing hitch, there are two things that you can do.

1. Have at least a ten million dollar liability ploicy.

2. Have an unabridged Bible, so you can have and say all the prayers ever printed, FOR THE INNOCENT PEOPLE YOU HURT, OR KILLED, including your own family.

Improper hitching is not something to mess around with.

You are either OK, or not OK. It's like being pregnant, you is or you ain't !!!!

If your not OK, by facts, not opinions, including your own opinions, do something before it's too late. Ask, inquire, read, learn, do something, but don't assume.

It is easily proven, by todays standards, in any court of law, if you were improperly rigged. If proven guilty, you may regret it and pay for it dearly, for the rest of your life.

Don't be foolish for the sake of a few bucks. If you want to save money, great, but don't go there, when it comes to proper rigging.

Then there is the personal injury, or death, to who?????

I have had to settle insurance claims with the estate's of people who wouldn't listen, or ignored, "proper rigging".

You can be one of two statistics.

1. A happy Airstreamer. OR,

2. A very sorry, and regretful, FORMER AIRSTREAMER.

Be the former. Everyone will love you for it.

Being the later, for the sake of a few bucks, is the wrong kind of "claim to fame", or "shame".

Be as safe as you can be, when towing. Then you only need to carry a pocket bible.

It's not for me, it's for you, your families and friends, and perhaps, someone you never met.

Now I will put my soap box away, again.

Andy

[toastie]

Thanks very much Andy, my 65 Caravel has new axle and electric brakes and
a Tekonsha Prodigy controller that is working great, I will fine tune my sway to perfection, again thanks very much to all...........

[bhayden]

The length of the rear overhang has everything to do with the load on the TV. The Envoy is relatively short which is generally a good thing for handling. It means the trailer has less leverage to push you around. It also means the tounge weight has less effect on the weight distribution. If the trailer ball were directly over the rear axle the tongue weight would equal the load on the rear axle. The farther you move it back the greater the load on the rear axle and the more weight that is removed from the front. My experience is that this unloading of the front is the major player in bad handling (different than sway).

Some back of the napkin calculations (300# tongue weight, 5' (SWAG, probably less) for overhang and 2'6"' for ball to bar mounts shows only 300 pounds load per bar to even out the load on your TV. Of course the proofs in the pudding and if you hitch it up and get adaquate deflection with the suspension of the TV level then all is good. However, I suspect there is a set of light duty bars in your future and even then I don't know if you can make it work. You may be better off going to the old style trunion bars and forget the Dual Cam. Going to a dealer that will set it up on the lot would be a lot more productive than arguing theory and a lot cheaper than buying more equipment that doesn't work. The other variable is load distribution. I suspect you're going to be one of the people that finds added tounge weight helps the towing characteristics. Even if you have the V6 in the Envoy you've got a big margin to play with before you reach the rated towing capacity.

Sway is a condition that is separate from the weight distribution. However, people commonly refer to the torsion bars as "sway bars". Technically not correct but WD hitches, properly set-up usually eliminate the need for added sway control. Sway is something that's hard to predict. While some trailers are more prone to sway than others (like single axle boat trailers with a huge outboard engine hanging off the back) it's really the whole combination of TV, trailer and hitch set-up. The good news is that unless it's a defective trailer design or seriously worn out TV it shouldn't take a big adjustment to eliminate the harmonic that's causing sway. Sometimes it's road conditions that cause sway; things like grooved pavement, washboard, side winds. That's when the sway control on the hitch is going to shine.

Some of the Envoys are equiped with a load leveling system. While that doesn't actual change the WD it might be very effective in fine tuning, especially adjusting for different loads. You really don't want to be mucking with the hitch angle once it's properly set and changing a link in the bars is a huge adjustment. It wouldn't be my first guess but you might just find the whole set-up tows better without the WD bars. You can use sway control that's separate from WD bars if it's needed. I think there's also a system that uses a single bar that was designed for boat & utility trailers that have a straight tongue. Of course that means all new gear on both the TV and trailer, not an inviting proposition.

[Inland RV Center, In]

Any, repeat, any automatic leveling system "MUST" be defeated so that it does not interfer with the load equalizing hitch.

Data obtained by Caravanner Insurance clearly showed the marked increase in the percentage of "loss of control" accidents when automative leveling was used in conjuction with an equalizing hitch.

The length of the hitch bars used in our testing ranged from 8 inches to 18 inches.

We found no significant difference it any handling, or loss of control, between the 8 inch to 18 inch hitch bars.

Conclusion to that suggests, that "IF" properly rigged "AND" adjusted, hitch bar length, as stated above, made zero statistical change to our data.

The paramount statistic showed two out of three (2 out of 3) 68 percent, loss of control accidents involving an Airstream trailer being towed, was caused by one or more of the following; addiing overload springs, having air shocks or air bags inflated to more than minimum pressure, no sway control, improper rated hitch bars, and improper torsion bar adjustments. The unknown reason was less than two (2) percent. The other 30 percent was for reasons other than "loss of control".

This data was based on the investigation and examination whenever possible, of more than one thousand (1,000) loss of control accidents, that were in the files of Caravanner Insurance Company, who only insured Airstream and Argosy trailers.

These are facts, not opinions, or guesses.

Andy

[dwightdi]

This man has a Reese dual cam system. The twin cams work with the W/D bars to provide a self centering moment to eliminate sway. That works of course only if the W/D bars are handling a load. With the smaller trailer the load of course will be less but the TV to Trailer weight is in the ratio that says some sway control will be beneficial. The Envoy's small overhand is a definite benefit and you should keep the ball as close as possible to the rear bumper for best performance

Toaster,You are getting some conflicting information on this thread indicating there some people with more engineering knowledge and trailer experience and some with just alot of years towing. Either find a good dealer you can trust and have him do it or, follow the recommendations of the manufacturer who originally engineered the hitch.

[toastie]

Thanks very much, my Envoy does have an auto ajust for leveling, I do know that with my setup going to 3 links on the chain, traveling down the e-way at 65 to 70 mph, you don't even know the trailer is behind you.......

[bhayden]

Originally Posted by Inland RV Center, In

The paramount statistic showed two out of three (2 out of 3) 68 percent, loss of control accidents involving an Airstream trailer being towed, was caused by one or more of the following; addiing overload springs, having air shocks or air bags inflated to more than minimum pressure, no sway control, improper rated hitch bars, and improper torsion bar adjustments. The unknown reason was less than two (2) percent. The other 30 percent was for reasons other than "loss of control"... These are facts, not opinions, or guesses.

Did the accident investigation prove these devices caused the accident or is it just that these conditions were present when investigating the accident? I find it very hard to believe "excessive speed", (road conditions, ice, wind, etc.), driver error (quick lane change, drifting off on the shoulder), or mechanical failure (tire blowout, worn steering components..) were never found to be the cause. Who'd 'ave thuk it

-Bernie

[bhayden]

Originally Posted by toastie

Thanks very much, my Envoy does have an auto ajust for leveling, I do know that with my setup going to 3 links on the chain, traveling down the e-way at 65 to 70 mph, you don't even know the trailer is behind you.......

In the end that's what you're looking for. You should stay within the guidelines provided by the equipment manufacturer but the optimal setting is going to depend on your individual set-up. Reese can only do so much with their generic instructions. You may in fact be getting little or no benifit from the Dual Cam sway control. It sounds like lighter bars would help. Just driving down the highway you don't have a sway condition but if you get passed by a convoy of semi's and find the trailer oscillating back and forth it's a little late to get out and adjust the hitch. You have such a low WD requirement it might not be possible to get the Dual Cam system to work regardless of which bars you buy (shorter bars will result in more tension for the same WD effect). The oldfashion friction dampener doesn't rely on the load in the bars. Generally it's not considered as good because it works to dampen sway rather than prevent it from occuring in the first place. But if you can't put enough load on the bars without moving too much weight to the front axle then it's probalby not doing it's job anyway.

You've got a light trailer and a decent margin on towing capacity. OTOH, it is a single axle trailer and the lighter the trailer the more it's affected by wind and to some extend road conditions. I'd want to do everything to get it close to optimum. Some of that is just going to involve driving. If you can drive down the road and not feel the trailer (and you can see it's not waving around like a kite in the wind) then you're pretty darn close.

[Inland RV Center, In]

Originally Posted by bhayden

Did the accident investigation prove these devices caused the accident or is it just that these conditions were present when investigating the accident? I find it very hard to believe "excessive speed", (road conditions, ice, wind, etc.), driver error (quick lane change, drifting off on the shoulder), or mechanical failure (tire blowout, worn steering components..) were never found to be the cause. Who'd 'ave thuk it

-Bernie

Physics proves the point.

As you increase the air pressure in the air bags or air lifts, it progressivley reduces the job for the torsion bars.

When you reduce the bend in the bars, because you have added an overload spring, or inflating an air device, then the bars transfer less weight, rendering the torsion bars progressively useless.

Think about it. If you artificially hold up the rear of the tow vehicle, the torsion bars don't have much of a job to do.

Additionally, when you increase the strength of the "fulcrum", the hitch transfers less weight therefore you add an excessive amount of weight to the rear of the tow vehicle, PLUS, you have removed weight from the front axle of the tow vehicle.

Perfect situation for a loss of control encounter.

Believe or not, your choice, but facts are facts.

Physics tells it like it is, which does not always agree with opinions., or hard to believe's.

I posted that there were other causes for accidents, but the rear end subject caused almost 70 percent of the loss of control accidents. Of course there were other causes, most of which, incidentally, could have also be avoided.

Generally speaking, owners who maximize safety, seldom ever have a problem. Speaks for itself.

Andy

[bhayden]

Originally Posted by Inland RV Center, In

As you increase the air pressure in the air bags or air lifts, it progressivley reduces the job for the torsion bars.

Not really. If you stiffen or raise the rear prior to loading the hitch then yes you need less tension on the bars to "level" the TV. However, it has basicly NO effect on the actual axle loading and as you point out the front of the vehicle will be light. If you set the tension to balance the weight (harder to do by measuring if you've overly stiffened the rear) then tension and load will be the same. I would heartilly agree that most peoples attempts to reengineer their suspension with air shocks or helper springs has a negative effect. For one thing a leave spring is designed to work best when it's flat. Air shocks are designed to do just that. That's also the job of the WD hitch. Air shocks could fine tune this BUT it's going to be a delicate balance. If you load up the old station wagon and then use the air assist to level out the suspension PRIOR to hitching up the trailer then you should be OK. Of course nothing is going to correct the situation if you've severely overloaded the TV to start with.

Think about it. If you artificially hold up the rear of the tow vehicle, the torsion bars don't have much of a job to do.

Draw a force diagram. Stiffening the rear suspension doesn't effect the job of the torsion bars. In fact if you add air to an airbag or air shock AFTER you hitch up the load on the torsion bars will increase (the opposite of what happens by raising the hitch with the trailer jack). If you tension the bars to restore the front rear height ratio the rig had before adding the tongue weight then you've evened out the weight distribution. If you raised the rear with air shocks then it will be raised back to that attitude. That's not good but probably better than being way light in the front with a vehicle that is oversprung in the rear.

Additionally, when you increase the strength of the "fulcrum", the hitch transfers less weight therefore you add an excessive amount of weight to the rear of the tow vehicle, PLUS, you have removed weight from the front axle of the tow vehicle.

You've lost me here, increase the strength of what "fulcrum"? Spring rates have some effect but the position they settle into isn't going to change the moment arm appreciably. The total weight the hitch transfers to the vehicle is the same. The distribution front to rear is basicly the same. Draw a force diagram. It APPEARS there is less load on the rear and if that's what people use to tension the bars then it will result in insufficient front axle loading.

For a explanation of the physics this post by nickcrowhurst is very good:
http://www.airforums.com/forum...sis-19236.html

[Inland RV Center, In]

bhayden

If what you say is true, then Airstream and Caravanner Insurance wasted a ton of money.

Please prove the point your trying to make, buy showing test data from a truck scale.

Andy

[bhayden]

Originally Posted by bhayden

In fact if you add air to an airbag or air shock AFTER you hitch up the load on the torsion bars will increase

Oops, that's just plain wrong. Let's say you start out with the trailer and TV level, that is to say that there's neither a V or a ^ stituation at the hitch looking from the side ("hitch down" it would be a shallow V, hitch high would be a slight ^).

Assumptions:
* The angle of the torsion bars is fixed at the hitch, lets call this 120 degrees from the TV around to the axis of the torsion bars (greatly exagerated but the principle is the same).
* In the "level" condition there is 180 degree angle between the frame of the trailer and the TV
* That leaves a 60 degree angle between the axis of the torsion bars and the trailer (360 degrees in a circle)

Starting in the level position and raising the back of the TV creates a ^ as viewed from the side. That means the angle is now greater than 180 between the TV and trailer. Again, greatly exagerated for effect lets say this angle is now 200 degrees. We made the assumption that the torsion bar angle at the hitch is fixed (a close approximation, that's what they're designed to do). This means the angle between the trailer and the torsion bars is only 40 degrees (360-200-60). A smaller angle means you've shortened the distance between the ends of the bars and the attachment to the trailer; therefore you've decreased the tension.

The same think holds true irregardless of what the starting condition is, =, ^ or V. Raising the back with airshocks always shortens the distance between the ends of the torsion bars and the frame of the trailer. If you have a load leveling system on your vehicle you should be able to use it to help unweight the bars when you're unhooking to test this.

-Bernie

[dwightdi]

The bars push downward on the cam followers mounted to the trailer. This is the force that generates the torque moment to push the front of the TV down. Using the trailer tongue jack to raise the front of the trailer and the back of the TV is what many people do to make it easier to hitch up the bars. You could also do the air bags or the pressurized shocks to to the same thing. This does mean the inflation of the air shocks after the unit is hitched up will raise the rear of the TV and will reduce the force on the bars and thereby decrease some of the load that was supposed to be transferred to the front wheels. Net result: Inflate your shocks before you hitch up and disable the ability to have the system readjust itself when you are on the road. I do believe that Andy's figures do not reflect what I know from the number of sway and run off the road or overturn the rig accidents I have recorded in my 12 years with the club. Most people were driving too fast for the conditions or their age. Many of the turn-over accidents have been coming down a hill too fast and the trailer tries to steer or pass the TV. Quite a few of the accidents occurred in road construction when the rig was trying to navigate a very narrow area and there were abrupt lane changes that the people were taking too fast. Two of the turn-overs were due to high wind shear when imerging from between two mountains and another coming out from wind disipating trees and entering a high cross wind. Getting sleepy was the cause for two more leave the road accidents. Bow waves from passing trucks caused two more. The stability of the rig might be part of a number these accidents but the majority of the fault lays with the drivers and road conditions.

[bhayden]

Originally Posted by dwightdi

Two of the turn-overs were due to high wind shear when imerging from between two mountains and another coming out from wind disipating trees and entering a high cross wind.

When traveling along highways that have been logged really really be aware of this. The wind shear along clear cuts can be severe. If there are high winds this is also a prime spot for trees to fall across the road. The wind shear causes a torque on the tree trunks and they literally explode. This is common in Washington forests. Logging companies also have a tendency to leave a small number of trees along the road. Don't know if this is because the timber is on government own right of way or if it's to mask the visual effect of the logging. The problem is the trees no longer have the support of the forest that was around them which makes them prime candidates for falling across the road. Ask me how I know

-Bernie

[toastie]

Originally Posted by bhayden

In the end that's what you're looking for. You should stay within the guidelines provided by the equipment manufacturer but the optimal setting is going to depend on your individual set-up. Reese can only do so much with their generic instructions. You may in fact be getting little or no benifit from the Dual Cam sway control. It sounds like lighter bars would help. Just driving down the highway you don't have a sway condition but if you get passed by a convoy of semi's and find the trailer oscillating back and forth it's a little late to get out and adjust the hitch. You have such a low WD requirement it might not be possible to get the Dual Cam system to work regardless of which bars you buy (shorter bars will result in more tension for the same WD effect). The oldfashion friction dampener doesn't rely on the load in the bars. Generally it's not considered as good because it works to dampen sway rather than prevent it from occuring in the first place. But if you can't put enough load on the bars without moving too much weight to the front axle then it's probalby not doing it's job anyway.



You've got a light trailer and a decent margin on towing capacity. OTOH, it is a single axle trailer and the lighter the trailer the more it's affected by wind and to some extend road conditions. I'd want to do everything to get it close to optimum. Some of that is just going to involve driving. If you can drive down the road and not feel the trailer (and you can see it's not waving around like a kite in the wind) then you're pretty darn close.

bhayden, my Envoy is a XL, longer wheel base, I live in the Motor City area and will be going down I-94 tomorrow on our first camping trip, lots of trucks, so if I feel swaying then what you are saying is maybe to go to a lighter bar, I will consider wind condition, and if that is the case, I will.....
I will.............

[scottanlily]

Hello all ,

I have read all the postings related to the WD here .The air shocks are a big NO. Why ,? because they are not a spring ,that is designed to lift or hold up the vehical .Yes they make them and on my 64 chevy ll nova I had them on it for some ...."attitude" .they are not designed to lift a vehical then add 500# of weight to the rear axle ,tongue weight. They are kinda of a poor mans lift .The air bag is a substantial improvement over the shock idea .Still
it isn't a leaf spring or coil spring either .In hitching my 68 travelall to the
tradewind ,I raise the trailer with the tongue jack ,hitch ,then install the
bars ,750# in my application to 6 links tensioned .I then let the jack down
and check it over .The tv and trailer are level ,and that is the MOST
important part of the whole WD business because if they are level (not 1"
down in the rear etc etc,) the loading of the frames of both tv and trailer
has been accomplished .The WD when hitched and loaded right ,there won,t be up in front ,or sagging rear or a need for any airbags .The principle is to use the weight distribution to level both the tv and trailer .The spring bars should have upward curvature too them when loaded ,about 1" min too 2"
as Andy has said exactly .Using the tongue jack is perfect for getting the
trailer hitched then leave it raised till you have the bars and chains sinched up in place .Let it down and again check to see if things are level .If not
raise up the trailer /tv with the jack and reset bar tension .If the curve when level is extreme on the upward curvature of your bars ,they are too weak
for the application ,you will need to go higher .If not much curvature ,
bars are too heavy ,go lighter bars .That installed curvature tells you the
tension the bars are under ,easy to see .This business about too much weight on the front axle ? Well ,make sure your tv and trailer are level ,thats the key .By the way I don't think I would do a sway test on the freeway
with semi's blowing by ,unless you want trouble .Hitch it up and look at the bars ,on the reese ,the bars will have some upward bend to them if loaded
right ,if not they will not help the sway ,the tension is needed for them to
work .Back to the air shock deal ,The WD is what you use to level out your
tv and trailer .If you try to raise the vehical to take tension off the bars,
thats totally the wrong approach to correctly use the WD ,argue it or not .
What I like about my none reese hitch is all the bars are the same length
but different # pound ratings ,not shorter .If the lightest reese bars are
too stiff ,somthing isn't working right with the vehical tv or trailer setup.
How about too small a tv or not enough tongue weight .That really needs to be adressed before putting on air shocks .

Scott

[ALANSD]

so if I am looking a t.vs and some were previously used with a fifth wheel...they will have overload springs. This is a no no for a 3/4 ton truck pulling a 31 AS? (Confused)

[dwightdi]

This type of truck will be overkill for an Airstream and will shake it to death. I have seen several people pulling with a heavy duty stake truck or a converted semi tractor. I do not know how they have modified them to make them compatible.

[Inland RV Center, In]

bhayden.

The point remains on the table.

Theories, formulas etc, cannot dispute truck scale readings.

Do the homework, as others have pointed out, and get "all" the weights.

Then you will see what we saw hundreds of times.

If I understand you correctly, your suggesting that all of the actual weight data we obtained, is phony?

Andy

[bhayden]

Originally Posted by Inland RV Center, In

If I understand you correctly, your suggesting that all of the actual weight data we obtained, is phony?

Not at all, in fact we're in violet agreement on the end result. My point is that a stiffer suspension does not in and of itself result in more weight on the rear axle or interfere with the way the WD hitch works. Beat up the trailer and adversly effect handling of the TV yes; in most cases.

When you hitch up a vehicle the front will rise. Tension on the bars will bring the nose back down. If you want even wieght distribution on the front and rear axle both wheel wells (or bumpers) will end up lower than before you added the tongue weight of the trailer. If you stiffened the rear it will sink less. If you've really gone overboard it may be almost inperceivable but it does have to go down some. The rig will look "goofy" and handle poorly although probably not AS poorly as if the front end is left light.

I don't see anything wrong with a well engineered load leveling system being used to adjust a TV BEFORE the hitch weight is added. I agree that it should not be used to compete with the job the WD hitch is designed to do.

I'd be interested to know more about the insurance company study. I do find it hard to believe that excess speed was not statisticly significant when every other piece of information I've seen (granted not trailer specific) points to excessive speed being the number one factor in crashes. I was personally involved in one court case involving a fatality accident and "expert witnesses" on the two sides had radically different interpretations of the evidence. Insurance companies hire crash reconstruction experts to prove a conclusion that best suits their interests. The study you reference may well have been an attempt to educate customers and reduce claims (a very economically sound reason to sponsor a study) or it may have been a way to avoid payment by "proving" the accident was the fault of the customer by modifing or incorrectly using the equipment. Either way I still find it hard to believe speed, driver error and road conditions aren't even mentioned.