Questions About Sway Control

[KeithInSpace]

The comment about sway control couldnt hurt isnt true at all,friction sway controls can be dangerous.Once a trailer sways,the fricion sway will try to keep the rig in the swayed position as hard as it tried to keep it from going there before the friction was overcome...

I disagree. The point of a properly tensioned/compressed friction-type sway control arm is to INCREASE the harmonic frequency at which your trailer achieves sway. This is done by creating resistance to the motion at all points. Increase that frequency enough and, as a matter of physics, the possibility of sway is all but eliminated. Saying that HAVING a friction sway control arm is more dangerous than NOT HAVING a friction sway control arm is simply incorrect.

The only sway control I would use is the Pro Pride or Hensley arrow.

Having said the above, I do not disagree that these seem to be more 'comprehensive' setups that promote a positive geometry between the tow vehicle and the trialer. Getting a $2,500 hitch head wasn't the first place I looked, though. But that's not to say it isn't where I'll end up...

 

[Bird]

I agree with you, Keith. I think the key point is a "properly adjusted" friction sway control. I've not done much trailering on snow or ice, except with a fifth-wheel and one ton dually, but over 35 years ago, heard and read about over tightening friction sway controls to the point that it affected steering on slick roadways; i.e., tended to hold the trailer and tow vehicle in a straight line.

 

[KeithInSpace]

100% on the spot, Mr. Bird. If you read the side of my Reese Friction Sway Control arm, it says to tighten the device "completely", as in, until it is not possible to tighten it any further.

I did that the first time and it resulted in a "stick and slip" situation I could actually feel in the driver's seat and a horrible groaning whenever I took a turn.

I've taken to completely tightening the device, then releasing it 1/4 turn. It still has immense binding strength, but works in a much smoother fashion.

I have to admit that passing big trucks gives me a tug on the steering wheel, but I blame this on my 1/2 ton truck, IRS, and shorter truck wheelbase more than the ineffect of one of the multiple systems I have employed to better my towing safety. Passing trucks at 70 MPH notwithstanding, I have NEVER felt any issue with crosswinds, crowned roads, or any other situation where the trailer felt 'out of line'.

If I showed one of those alternate towing systems to my wife, I'd bet she'd be interested in them.

As for trailering on ice, I don't think I have the stones for that. Doesn't sound like much fun.

 

[zzvyb6]

Here's my favorite adventure. 85 mph across I-696. There are 100 50 lb bales. As you might tell from the chassis droop (or lack of it), the tongue load is pretty low. I ran it with frame level. Not a spec of sway. Hitch is clamped tight. The biggest contributor to stability in this rigging (besides the dual axles), is the short distance front the ball to the tow vehicle's rear axle. That's why a 5th wheel is probably the best system for towing a heavy trailer: when a tow angle develops, the hitch lateral force component is in phase with the other rear axle forces instead of out of phase. That's why swaying (trailer yaw velocity) begins.

The boat tug is/was actually much more oscillatory that the hay. (Frame not level). All the other engineers were worried about the transmission temperature. It was 135 degrees the whole trip. (185 parked in the driveway idling. There's a driver info center on Corvette that shows trans temp among other things)...

 

[Bird]

Here's my favorite adventure. 85 mph across I-696.

Yep, that's unusual enough to attract attention. I used to attract attention myself when I went fishing pulling my Dad's 16' boat with a 35hp Evinrude behind my 1962 Austin-Healey Sprite. Everyone who came up behind me was anxious to go around, even when I was driving the speed limit or more, because from the rear, it appeared the boat and trailer were going down the road alone. And I usually drew a few onlookers at the launch ramps waiting to see if I was going to be able to pull the boat out of the water. I never had a problem, though.

 

[Bird]

I have to admit that passing big trucks gives me a tug on the steering wheel

I've never pulled a travel trailer, except fifth-wheels, that didn't feel that tug, and it usually scares new RVers.

For those who have never pulled a travel trailer . . .. When a big truck passes you, as it goes by, it will feel as if something pulled the front of the trailer and rear of the car/truck you are driving toward the truck. It can be quite a scare for a novice, and some will almost instinctively hit their brakes, which, of course is the worst thing you can do. You soon learn that the best thing to do is nothing. It's just a momentary thing that will be over with before you know it if you don't panic and do something foolish.

Of course if a trailer does get to swaying or fishtailing, again a novice is likely to hit the brakes, and wreck out. The most effective way to stop the fishtailing, assuming it's a trailer with brakes, is to manually apply the trailer brakes, while not applying the foot brake. In fact, you can even slightly depress the accelerator pedal if you wish and pull everything back straight.

 

[KeithInSpace]

For those who have never pulled a travel trailer . . .. When a big truck passes you, as it goes by, it will feel as if something pulled the front of the trailer and rear of the car/truck you are driving toward the truck. It can be quite a scare for a novice...

Danger...Engineering Content: pv=mrt. All else being equal (mass and temperature on the right side, specifically), pressure MUST react inverse to velocity to maintain equality in the equation. The velocity between a rig and travel trailer (tall flat sides) increases, especially when passing the "wake" at the front of the rig. The resulting small decrease in pressure over the large surface area of the travel trailer gives it a VERY distinct and definite "tug" TOWARD the rig. While the effect is brief (as Mr. Bird says), it is quite freaky, to say the least.

Different tow vehicles react in different ways.

In a 5th wheel, you don't notice the effect at all. This is because the kingpin is directly over the axle. I'll bet you money, though, that the trailer DOES get an inch or two closer to the rig, although you can't feel it.

In a bumperpull, it literally pulls the bumper toward the rig, forcing a steering correction to "straighten" the tow vehicle.

In my brother's F350 diesel club-cab, long bed dually (long wheelbase, solid rear axle, very little sidewall give) the effect is somewhat negligible. As I previously mentioned, his wife recently drove that truck 1,500 miles through mountain passes with trailer behind.

In my truck (LT tires in back, IRS geometry in back, shorter wheelbase, less overall weight) the effect is VERY noticible. I am experienced, so I'm OK with it, but you need to be awake and alert.

As Mr. Bird mentions, if you hit your brakes hard at that very moment, there is an "angle" between the trailer and tow vehicle...therefore, the risk of a difficult-to-control maneuver (or possibly jack-knife) at that instant is distinctly increased.

 

[wkpoor]

I never thought about it before but a combination of long wheeel base truck
( ie most cargo vans) and trailer with axles far back would make for a real stable combination. Guy here at work said he feels vans are the best BP tow vehicles because wheel base and weight distribution.

 

[VitaBene]

I never thought about it before but a combination of long wheeel base truck
( ie most cargo vans) and trailer with axles far back would make for a real stable combination. Guy here at work said he feels vans are the best BP tow vehicles because wheel base and weight distribution.

I have heard the same but never towed heavy with a van. A buddy tows a decent sized trailer with a short bus and it does good but perhaps the stripper pole gives it stability!

 

[wkpoor]

I have heard the same but never towed heavy with a van. A buddy tows a decent sized trailer with a short bus and it does good but perhaps the stripper pole gives it stability!

I'm not sure what tow heavy is but I pull a 14K deckover with mine and I feel it does well. Sure could use more motor at times though but it gets the job done and for a fraction of the price. My FIL wheened me over several yrs ago from PU's and I've yet to go back. If the big 2 would just offer them in 4WD I can't imagine sales not doubling. If and when I get another PU it won't be 2500/250 or 3500/350. I'll go for 450 or 550. Here again I'll bet those can be had for less money and why not have more for less.