Friction anti-sway device use in rain or wet roads

I've never had an issue with towing in the rain with the sway bar tightened as I normally have it. But my understanding is that you should loosen it - and reduce your towing speed.

The manufacturer tells you to loosen the friction sway bar when the roads are slippery and where traction is reduced. The sway bar works to resist any change of angle between the TV and TT...think about the screw that holds a pair of scissors together...the tighter the screw is, the harder it is to open/close the scissors. The tighter the sway bar is, the more force is required to change the angle between the truck and trailer. If the bar is tight enough, it is possible for the friction of the sway bar to become greater than the traction of your tires on the road.

Say you're driving on a slippery road and want to turn right. As you turn the truck, the tires need sufficient grip to overcome the resistance of the sway bar to begin to angle the trailer around the corner. It's possible for the tires to lose grip if too much resistance is presented by the sway bar. When that happens, the truck will be pushed into an understeer condition and begin to slide straight ahead. Kind of like being on ice, except you now have the weight of the trailer pushing the truck, so regaining control is difficult if not impossible. Obviously if this happens at highway speeds you'll be in the ditch before you can say "Holy Shift!".

Now, when to loosen it and how much to loosen it? That depends on a lot of variables, like the condition of your tires, how much water is on the road if it's raining (hydroplaning), how deep the snow is if it's snowing, probability of ice, how tight you normally keep the sway bar, etc.

One of the reasons I migrated to the Hensley in 2002...I was never sure if the sway bar was tightened the right amount. I recall a few times making it extra snug because it was a windy day, only to have it start raining with no where to pull over and loosen it. Your only choice is to slow down and hope you don't get surprised by understeer at the wrong time. I worry a lot less about the weather with the Hensley.

Read the directions. As I recall they weren't supposed to be used on slick roads.

It is as Burbman stated above. That said, I used a friction sway control for many years before purchasing my Hensley and never once loosened it up for rain or pulled over to adjust it. The few times I towed in snowy conditions, I did not use at all. Never had a single problem with understeer with it on. It may well have something to do with how well your WD hitch is adjusted and how much weight you are putting on the front axle of the truck.
Barney

Good point Barney! Although I would say not how much weight you put on the front axle, but how much weight you removed from the front axle....with daelb's Chevy, a correctly adjusted WD setup should be restoring the front axle to it's unloaded weight...if it's not, and the front axle is less lightly loaded while towing, that would also increase the chances for understeer.

I agree with you that "normally" if your tires have adequate tread, the interstate is in good shape and there isn't a lot of ponding on the road from rain, and your WD hitch is adjusted correctly, there shouldn't be any need to loosen the tension on the sway bar.

The only time I did not use my friction sway bar was on ice or snow covered roads. Even on wet roads, I kept mine as tight as on dry roads. When I was traveling on ice and snow, my speeds were slower so sway was not an issue that needed correcting.

It is correct that the friction sway control (FC) bar will resist allowing the trailer to return to normal.
However, I believe many people over estimate the magnitude of the effect.

The most commonly sold FSC is factory-set to produce a yaw-axis torque of about 500 lb-ft.
If the 500 lb-ft of torque is applied to a TV with a 130" (10.8') wheelbase, the front tires must generate a lateral force of 46# to counteract the torque.

If the front axle is carrying 3000#, typical tires must be turned about 0.14 degrees on dry pavement to generate a lateral force of 46#.
Required increases in steering angle for other surface contitions might be: wet pavement = 0.2 degrees, packed snow and dry ice = 0.3 degrees, glare ice = 0.55 degrees.

So, yes, a FSC can induce some "understeer".
However, the added steering angle required to overcome the "understeer" is relatively small compared to the maximum tire slip-angle of 5-6 degrees at which the lateral force begins to plateau.
The required added angle might be so small as to be undetected by the driver.

The "stiffening" effect of the FSC might be noticed when coming out of a curve.
When not towing, the the camber and toe in of the TV's front suspension will tend to straighten the steering tires.
When towing with a friction-based SC, the FSC torque will tend to oppose the camber and toe in effects and reduce the TV's self-straightening.
It might or might not be possible for the TV to self straighten.

However, as long as the driver is aware that it might be necessary to provide some assistance in the straightening process, the FSC yaw-axis torque should not cause problems.

Ron

When I used to run single friction sway control, I never loosened it in the rain, or when backing up for that matter.

Thank you all for your responses. The detailed responses made my head spin a bit, but, I get the gist. Great group here.

Ron3rd wrote:
When I used to run single friction sway control, I never loosened it in the rain, or when backing up for that matter.

x2. Well, occaisionally while backing, if I thought of it, or when it groaned and popped so much it reminded me. I never heard of loosening for wet/snow covered pavement :E