Here're my thoughts on sway, which I posted in the Files section of Yahoo Scampers. Some may disagree, but these are my thoughts based on experience and reading RV groups for more than a decade.
BTW, relative weight doesn't always do it -- I had a nearly uncontrollable sway incident on a curved, banked, wet gravel road in BC, where my 1700 lb Scamp 13 pulled my 4000 lb half-ton pickup around like they weighed the same.
Here are one person's thoughts on sway control, based on personal
experience and the experiences of others -- YMMV!
Below is a copy of the notes from a Reese friction sway control's
Please read note No. 4 of the PDF -- How many folks actually stop
and pull over to the side of the road to disable their friction sway
control when driving in the rain or on gravel roads, etc., esp when
the rain first hits and the oils are starting to float on the road?
In fact, how many folks have even read Reese's note?
There are basically three kinds of sway that we encounter when towing:
A. That caused by a big truck's passing on a highway -- This, I believe,
is what most folks think about when sway is mentioned.
B. The reaction that the trailer has against the tow vehicle (TV)
when a change in direction happens, including a return from a change
in direction -- About the very worst is a turn while descending a
hill because the trailer is putting more weight on the TV rear and
lifting the TV front end while pushing to the side.
C. The reaction that the trailer has on the whole rig when its "speed
of instability" is reached and it starts to bounce and lurch from
side to side in ever-increasing distance.
The last two are the most dangerous, but sometimes vehicles are on
the very edge of the last one © when a big truck goes by -- The
resulting mess is blamed on the big truck, but that's really not
the base cause.
If the rig isn't balanced right (see Note No. 2 below about
first-line defense), then all the sway control does for you is
extend your "speed of instability" by a small margin and promote
a false sense of confidence, esp after a couple of big trucks
have passed by without incident.
If a friction sway control is set properly, at first it will resist
the trailer's tendency to sway and push the TV's rear to one side,
esp the momentary sway caused by encountering big trucks -- This
is why most folks have a sway control.
However, if the force is sufficient, as in a curve, the friction
sway control will slide to its new position -- It will now tend
to resist coming out of the turn with as much force as it used
going in -- If the road surface is slippery enuf, then either
going into the turn, or coming out, the sway control will not
allow the trailer to track properly and it will try to go into
a skid, yanking on the TV rear and possibly causing loss of control
-- Hence, the manufacturer's instructions to disconnect it in
In the case of major uncontrollable sway, as in C. above, the
friction control is tending to fight every steering correction
you try to make...
BTW, the Dual Cam and Equal-i-zer sway controls appear to be far
superior in this regard because they always try to straighten the
trailer behind the TV -- Unfortunately, they are only available with
weight distributing hitches (WDH).
QUOTE FROM THE REESE PDF FOR FRICTION SWAY CONTROL:
1.SWAY CONTROL CANNOT BE USED ON TRAILERS WITH SURGE BRAKES.
2.Trailer loading: Proper trailer loading is your first-line
defense against dangerous instability and sway. Heavy items
should be placed on the floor in front of the axle. The load
should be balanced side-to-side and secured to prevent shifting.
Tongue weight should be about 10-15 percent of gross trailer
weight for most trailers. Too low a percentage of tongue weight
can cause sway. Load the trailer heavier in front.
3. The handle (5) is an on/off device. The bolt (7) below is
for adjustment only.
4. When towing during slippery conditions such as wet, icy, or
snow-covered roads or on loose gravel, turn on/off handle (5)
counterclockwise until all tension is removed from unit. Failure
to do so could prevent tow vehicle and trailer from turning
5. Do not speed up if sway occurs. Sway increases with speed.
Do not continue to operate a swaying vehicle. Check trailer
loading, sway control adjustment, and all other equipment,
until the cause of sway has been determined and corrected.
6. Never paint
or lubricate slide bar (6).
Regarding front wheel drive (FWD), it's not sway controls that
are the question, it's a WDH to get the front wheels back down
on the ground properly to retain steering and control (and traction)
against the forces of sway -- This has to be offset, however,
by a serious look at the trailer frame because WDH takes the
weight off the rear of the TV and puts it on the front AND on
the trailer axle (and puts bending stresses on the frame in
However, if one had too light
a front on FWD, one could
temporarily hide that condition from oneself by installing a
friction sway control >>> But only until the new limit of control
was reached...which will likely be at a higher speed with greater
The bottom line on sway is to get your balances right, and stow
your heavy stuf as low and close to the axle as possible -- If
possible, do what you can to change your tow geometry -- Once
you have done all that, then add the anti-sway control for a
little insurance if you want.
On my Dodge D150 pickup, after towing for many tens of thousands
of miles, I had a near-miss on a descending curve on a wet gravel
road at slow speed -- My 1,700 91S13 slung my 4,500 lb truck like
I wouldn't have believed had I not experienced it -- Following that,
I rebalanced the load in truck itself to get more weight off the
rear and onto the front, modified the receiver hitch to move the
ball forward 2" and modified the ball mount to move it forward
another 2" -- Those things made a surprising improvement in
For those who don't already know this, here're some tow geometry
Long TV wheelbase is good
Short TV overhang (rear axle to ball) is good
Long trailer tongue (ball to trailer axle) is good
Short trailer overhang (trailer axle to bumper) is good
The worst possible things you can do are to have your tongue
weight too light
and to put a lot of weight out on the trailer
bumper -- Installing a longer ball mount (aka stinger) is NOT
a good thing.