Towing stability studies

Not so simple actually. There are other variables than hitch weight:

1. A glider trailer with a foil-shaped dog house.
2. Independant suspension with variable geometry as seen on many
smaller tow vehicles. This matters
a great deal if the rear suspension compresses unevenly or
rebounds unpredictably after bottoming.
3. The weight distribution of the tow vehicle itself.
4. The distance from the tow ball to the rear axle of the tow
vehicle AND the trailer.
5. How well side to side motion of the tow vehicle rear axle is
limited.
. 6. Side-wall stiffness of the tires.

I could go on. Even if the trailer weight on the hitch is proper at
rest, it may change radically over bumps, under cornering loads or
during heavy acceleration or braking,especially if there's a lot of
weight at the ends of a long trailer (think spare tire, rigging stuff,
tools, etc.) A trailer which is well behaved with no traffic may do
strange things when passing a line of tractor-trailers. Unequal side-
to-side tire inflation ON ANY AXLE OF THE COMBINATION can provide real
adventure.

Some suggestions:

Don't load the hitch anywhere near the tow vehicle weight limit.
You want to set things up so 7-10% of the trailer weight is on the
hitch and the suspension doesn't bottom when you bounce on it. If the
standard suspension bottoms, add helpers. Add aftermarket sway bars
if the rear suspension allows side to side movement.

Check your tire pressures often, at least every fuel stop. While
you're at it, touch the bearing caps with the BACK of your hand to
check for overheating.

Good tires and shock absorbers are still cheap compared to gliders and
trailers.

A good place to work out the kinks is a big empty parking lot on a
weekend. Accelerate in a straight line, tug the steering wheel
sharply to one side or the other and release it. Start slowly and
increase speed in small increments.

If you can stand the size and poor gas milage, it's hard to go wrong
with a pickup or commercial van with a solid axle and a factory tow
package, BTW

My suggestions/opinions only; your milage may vary.

Ray Warshaw
1LK


There's not a whole lot there, but that reflects the fact that
stability is pretty simple: have at least 7% of the trailer weight on
the hitch (up to the towcar's limit), and concentrate mass low down
around the axle.

If you can stand the size and poor gas milage, it's hard to go wrong
with a pickup or commercial van with a solid axle and a factory tow
package, BTW

My suggestions/opinions only; your milage may vary.

Ray Warshaw
1LK

I'm hoping for a solution to trailer sway in the Acura MDX that I am
waiting for delivery next week. The MDX has a Trailer Stability Assist
program included in the Vehicle Stability Assist system. Of course,
TSA doesn't fix whatever is causing the sway in the first place but at
least it should eliminate the effects. I've tried various solutions on
my trailer and the one with the greatest positive effect was inflating
the tires to max rated pressure. I think the fundamental problem on my
trailer is the wimpy torsion bar suspension.
Steve

On 26 Jan, 18:20, wrote:
If you can stand the size and poor gas milage, it's hard to go wrong
with a pickup or commercial van with a solid axle and a factory tow
package, BTW

My suggestions/opinions only; your milage may vary.

Ray Warshaw
1LK

I'm hoping for a solution to trailer sway in the Acura MDX that I am
waiting for delivery next week. The MDX has a Trailer Stability Assist
program included in the Vehicle Stability Assist system. Of course,
TSA doesn't fix whatever is causing the sway in the first place but at
least it should eliminate the effects. I've tried various solutions on
my trailer and the one with the greatest positive effect was inflating
the tires to max rated pressure. I think the fundamental problem on my
trailer is the wimpy torsion bar suspension.
Steve

If you have an airfoil shaped fin box on the trailer try fitting a
'spoiler strip' to either side of the finbox!

I had a ventus B Turbo in a Komet II trailer that used to quietly
dance behind what was normally a perfect tow vehicle. The sway was
usually kicked off by a passing car or when overtaking a big rig or
bus on the motorway. Taping 2 25 mm aluminium right angles about 1m
long, vertically about 100mm behind the leading edge of the fin box
killed the horizontal lift on the box and transformed the handling.

I often got some very strange looks from other club members about it
but I swear it worked a treat.

After all of normal fixes failed to improve handling behind my Toyota
4-Runner a Al-Ko AKS 1300 ball stabilizer solved it totally. Not cheap
and requires a special ball but less cost than fixing a tumbled
trailer/glider.
http://tinyurl.com/3yne64

On Jan 27, 7:37 am, nimbusgb wrote:
On 26 Jan, 18:20, wrote:



If you can stand the size and poor gas milage, it's hard to go wrong
with a pickup or commercial van with a solid axle and a factory tow
package, BTW

My suggestions/opinions only; your milage may vary.

Ray Warshaw
1LK

I'm hoping for a solution to trailer sway in the Acura MDX that I am
waiting for delivery next week. The MDX has a Trailer Stability Assist
program included in the Vehicle Stability Assist system. Of course,
TSA doesn't fix whatever is causing the sway in the first place but at
least it should eliminate the effects. I've tried various solutions on
my trailer and the one with the greatest positive effect was inflating
the tires to max rated pressure. I think the fundamental problem on my
trailer is the wimpy torsion bar suspension.
Steve

If you have an airfoil shaped fin box on the trailer try fitting a
'spoiler strip' to either side of the finbox!

I had a ventus B Turbo in a Komet II trailer that used to quietly
dance behind what was normally a perfect tow vehicle. The sway was
usually kicked off by a passing car or when overtaking a big rig or
bus on the motorway. Taping 2 25 mm aluminium right angles about 1m
long, vertically about 100mm behind the leading edge of the fin box
killed the horizontal lift on the box and transformed the handling.

I often got some very strange looks from other club members about it
but I swear it worked a treat.

I'll second your comment. I have a Komet trailer with a symmetrical
airfoil tailfin. Gusts from passing large trucks would cause it to
sway. I think the curling air caused just the right angle of attack,
and an ugly harmonic say until out of the wake of the truck. I also
added the right angle aluminum bars just as you described. These
spoilers really added 5-15mph more safe speed to the trailer, very
dramatic change.

As far as mechanical side sway [not the aerodynamic type] changing to
stiff sidewall tires "V-rated" and keeping them inflated solved the
issue for me. Factory tires/ones you get when you buy a car can be
terrible.
Instead of 32psi I keep the front tires inflated to 35psi and the
rears at 40psi. Also helps gas mileage.
Chris

On Jan 27, 7:12 am, chris wrote:
On Jan 27, 7:37 am, nimbusgb wrote:



On 26 Jan, 18:20, wrote:

If you can stand the size and poor gas milage, it's hard to go wrong
with a pickup or commercial van with a solid axle and a factory tow
package, BTW

My suggestions/opinions only; your milage may vary.

Ray Warshaw
1LK

I'm hoping for a solution to trailer sway in the Acura MDX that I am
waiting for delivery next week. The MDX has a Trailer Stability Assist
program included in the Vehicle Stability Assist system. Of course,
TSA doesn't fix whatever is causing the sway in the first place but at
least it should eliminate the effects. I've tried various solutions on
my trailer and the one with the greatest positive effect was inflating
the tires to max rated pressure. I think the fundamental problem on my
trailer is the wimpy torsion bar suspension.
Steve

If you have an airfoil shaped fin box on the trailer try fitting a
'spoiler strip' to either side of the finbox!

I had a ventus B Turbo in a Komet II trailer that used to quietly
dance behind what was normally a perfect tow vehicle. The sway was
usually kicked off by a passing car or when overtaking a big rig or
bus on the motorway. Taping 2 25 mm aluminium right angles about 1m
long, vertically about 100mm behind the leading edge of the fin box
killed the horizontal lift on the box and transformed the handling.

I often got some very strange looks from other club members about it
but I swear it worked a treat.

I'll second your comment. I have a Komet trailer with a symmetrical
airfoil tailfin. Gusts from passing large trucks would cause it to
sway. I think the curling air caused just the right angle of attack,
and an ugly harmonic say until out of the wake of the truck. I also
added the right angle aluminum bars just as you described. These
spoilers really added 5-15mph more safe speed to the trailer, very
dramatic change.

As far as mechanical side sway [not the aerodynamic type] changing to
stiff sidewall tires "V-rated" and keeping them inflated solved the
issue for me. Factory tires/ones you get when you buy a car can be
terrible.
Instead of 32psi I keep the front tires inflated to 35psi and the
rears at 40psi. Also helps gas mileage.
Chris

I've heard about the spoiler fix but never tried it. I was told to put
the spoilers at the trailing edge of the fin. I also talked to a Komet
factory rep at an SSA Convention a few years back and he told me the
cause of sway was absolutely not aerodynamic!
Steve

Have you noticed how the boxes on new trailers are now square

Indeed Ian

However, I think a lot of swaying trailer diseases is caused by vortex shedding.
Which is why architects tend not to make too symmetrical buildings.

This is usually triggered by a disturbance to the streamline flow - such as
passing a large vehicle.

Having a turbulator about 30% forward of the back of the trailer works very well
on mine. Don't know who fitted it - but there is a little (about 8mm high)
aluminium profile just ahead of the opening section. Probably fitted to deflect
water past the gap. Mine is a 1971 Anschou trailer with the little wing shaped
doghouse for the fin, but it tows very well.

nimbusgb wrote:
Have you noticed how the boxes on new trailers are now square

I did almost the same with my LAK trailer but used pop rivits and
sealer when I was towing with a Chevy Blazer. Without them, the rig
was dicy over 60 mph; after they were added it was rock-steady at
Arizona highway speeds (75 mph). The P/U I replaced the Blazer with
probably wouldn't have needed them, though.

Ray Warshaw
1LK


I had a ventus B Turbo in a Komet II trailer that used to quietly
dance behind what was normally a perfect tow vehicle. The sway was
usually kicked off by a passing car or when overtaking a big rig or
bus on the motorway. Taping 2 25 mm aluminium right angles about 1m
long, vertically about 100mm behind the leading edge of the fin box
killed the horizontal lift on the box and transformed the handling.

I often got some very strange looks from other club members about it
but I swear it worked a treat.

nimbusgb wrote:

If you have an airfoil shaped fin box on the trailer try fitting a
'spoiler strip' to either side of the finbox!

I had a ventus B Turbo in a Komet II trailer that used to quietly
dance behind what was normally a perfect tow vehicle. The sway was
usually kicked off by a passing car or when overtaking a big rig or
bus on the motorway. Taping 2 25 mm aluminium right angles about 1m
long, vertically about 100mm behind the leading edge of the fin box
killed the horizontal lift on the box and transformed the handling.

I often got some very strange looks from other club members about it
but I swear it worked a treat.

Do you have any photos of this installation? I'm wondering if it'll
help settle down my Komet.

Jeremy