When to release friction anti-sway bar in snow & why?

ktmrfs wrote:
If the friction forces from the sway bar are greater than the friction between the tires and ground, when you go to make a turn, the trailer/tow vehicle junction (tongue) won't pivot and you'll be turning one LONG vehicle. If the friction difference isn't much, the trailer may pivot, but not enough and still not track straight.

Or, if conditions change it could have enough friction to the road to turn as you turn, but then if you hit a very low friction surface after the turn, the trailer can't straighten out. Not enough friction to the road surface to overcome the sway control.

Either case can be bad.

Now it does take a very low friction surface for that to happen, but that's what can happen with glare ice, hardpacked snow etc.

This is the best answer, and with no preaching.
Now think about the dual cam, and some others, that do not have the release option. If tire traction is low, you might have a problem.

Driving and towing in snow is no big deal

:@

Even professional semi drivers sometimes loose control of their rigs with disastrous results.

The only time we have ever towed our TT on snow is when we got caught in a snowstorm while traveling in Wyoming on Labor Day several years ago. :E

Not fun no matter how slow you go. I would never intentionally tow any kind of trailer in the snow. Why tempt fate?

It is correct that the friction bar will resist allowing the TV/TT articulation to return to normal.
However, I believe many people over estimate the magnitude of the effect.

The most commonly sold friction bar SC (FSC) is factory-set to produce a yaw-axis torque of about 500 lb-ft.
A 25' TT will have a distance of about 18' from ball to axles.
This means the FSC torque would equate to a lateral force of about 28# at the TT's tires.
On dry pavement, if a 6,000# TT swings to an angle of 1 degree, its tires will develop a lateral restoring force of about 500#.
The TT would need to have an "off tracking" angle of only about 0.06 degree to balance the FSC torque.
On snow or ice, the angle might increase to about 0.2 degree.

For comparison, an angle of 0.06 degree would result in the rear end of a 25' TT being out of line by about 0.35".

Some people also over estimate the magnitude of added steering force required to overcome the torque generated by the FSC.

If the 500 lb-ft of torque is applied to a TV with a 120" (10') wheelbase, the front tires must generate a lateral force of about 50# to counteract the torque.
If the front axle is carrying 3000#, the tires must be turned about 0.15 degrees on dry pavement to generate a lateral force of 50#.
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 friction bar SC 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 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 torque should not cause problems.

FSC manufacturers typically advise to loosen the friction bar when towing in low-traction conditions.
Since the FSC bar can be loosened without affecting weight distribution, you still have the WDH effect.

Manufacturers of integrated WDH/SC devices (which generate considerably more yaw-resting torque than do FSC devices) do not specify any reduction in sway-control force during low-traction.
Reducing the yaw-resisting torque also would result in less load transfer.
I'm guessing these manufacturers do not believe there is any significant risk in using their devices in low traction.

Ron

Even professional semi drivers sometimes loose control of their rigs with disastrous results.

Yes. But not because their anti-sway bar is too tight. :)

Ron

A fellow I teach skiing with, had a 32ish foot travel trailer, He did not loosen the friction bar up. BUT like myself, we did leave the WD bars full taut! Later I went to a dual cam after loosing a WD bar on a trip over stevens pass..... no real difference that I could tell with a WD vs the DC. I never had a friction bar on the trailer.

If you are in an area that require chains in certain conditions. I preferred the chain chain vs cables when towing. UNLESS I had chains on all fours of the truck, then cables went on the front.

marty

Ron Gratz wrote:

Even professional semi drivers sometimes loose control of their rigs with disastrous results.

Yes. But not because their anti-sway bar is too tight. :)
Ron

True. They weren't using any. :B

3oaks, your point is well-taken -- why tempt fate? But sometimes, we are overtaken by bad weather. Especially out West, in the winter they will sometimes predict rain, and it will turn to snow unexpectedly. So, for example, we are hoping to go to Utah next week for some cold-weather camping. Storms are predicted. It is not supposed to snow where we are traveling and at our destination. But it might. So that is why I need to know how to adjust the sway bar. And I really appreciate the tips that you all have provided!

profdant139 wrote:
---It is not supposed to snow where we are traveling and at our destination. But it might. So that is why I need to know how to adjust the sway bar.---

Many years ago in the month of April, we took the Zion-Mount Carmel tunnel on our way from Zion to Bryce.

At the Zion side, the pavement was clear and dry.
When we exited the tunnel one mile later, the pavement was covered with snow and ice.

I didn't adjust the sway bar -- but I did adjust my driving.

I just remembered to steer not only into but also out of the curves rather than relying solely on the self-centering action of the front tires.

During our 11 years in Ely, MN, we usually headed south with our trailer for the winter.
We often encountered snow and ice on our departure from or our return to Ely.
I never felt a need to adjust the sway bar -- but I did adjust my driving.

Enjoy your trip to Utah,

Ron

3oaks wrote:

Driving and towing in snow is no big deal

:@

Even professional semi drivers sometimes loose control of their rigs with disastrous results.

The only time we have ever towed our TT on snow is when we got caught in a snowstorm while traveling in Wyoming on Labor Day several years ago. :E

Not fun no matter how slow you go. I would never intentionally tow any kind of trailer in the snow. Why tempt fate?

3 Oaks - if you want to stay put when it snows I have no problem with that.

However, staying put is not always an option that some of us can take easily; for instance some of us have jobs that our employers want us to put in a fair days work for a fair days pay. In situations such as this you have many choices. A couple of those choices could include:
1) staying put, (screw the job I didn't need it anyways)
2) burying your head in the sand and tempting fate so to speak
3) being proactive and learn ahead of time things you should do and things you shouldn't do and drive accordingly. This is what I believe the OP was doing.
Your choices my vary, I pretty much need my job. I can't remember ever in 40 plus years of driving of getting in a accident in the snow.

I do however have a rule of thumb that I use. If the 18 wheelers are staying put - I should stay put.
If the 18 wheelers are chained up - I should be chained up.
If the 18 wheelers are running at reduced speed - I should be running at reduced speed.

And finally, and probably mostly - the bridges ice up before the road. Be aware of this as you approach any bridge in adverse conditions.

bid time, in defense of 3oaks, his point is that if we don't have to tow in really bad conditions, we might want to choose not to. Work related driving is entirely different -- it is not optional. Recreational driving is somewhat more optional.

My upcoming trip to Utah, for example, is now on hold until the weather forecast comes into clearer focus -- if I am going to have to tow a trailer through 600 miles of blizzard, I might just choose to stay home, sad as that is. I have killer tires on my truck, and chains for both the truck and the trailer, but there is a limit to my courage. (Sigh.)