Which Tow Vehicle

On Oct 16, 4:46 am, Eric Greenwell wrote:
Dan G wrote:
On Oct 12, 3:57 pm, "01-- Zero One" wrote:
So to say that "Towing is simple. Follow these rules, and your rig will
be stable in all conditions and not need stabiliser hitch." is in my
experience a gross oversimplification.

Think we'll have to agree to disagree - but I'd like to know of
examples where these guidelines were met, but the rig was still
unstable.

My '89 Dodge Caravan and ASH 26 E trailer meets all your rules and is
stable at 60 mph. At 70 mph, it's starting to quiver, and I've never
dared go faster. So, is the rig "stable" or "unstable"?

What's the speed limit for a towing vehicle in the US? In the UK it's
60, so your rig would be "stable", though of course it would be
preferable to have a higher safety margin in the event of cross-winds
etc.

Let me try and explain this another way:

*if your trailer is trying to lift the rear of your tow vehicle when
hitched, it will have reduced stability than if it's pressing down.

*If your trailer has a heavy mass at the far end, it will have reduced
stability compared to if it had that mass in low down over the axle.

*If your trailer has underinflated tyres, it will have reduced
stability compared to if it had correctly inflated tyres (and they
might go "bang", too)

*If your trailer weighs more than your towcar, it will have reduced
stability compared to if the towcar was heavier than the trailer.

I hope that's clearer. The Bath University guidelines were also
developed using average Euro cars - I would not expect an tall,
unstable American SUV or pickup with ancient suspension to be
particularly stable in many circumstances, even when not towing. More
recent models with relatively modern suspension should, of course,
fare better.


Dan

"Dan G" wrote in message
ups.com...
On Oct 16, 4:46 am, Eric Greenwell wrote:
Dan G wrote:
On Oct 12, 3:57 pm, "01-- Zero One" wrote:
So to say that "Towing is simple. Follow these rules, and your rig
will
be stable in all conditions and not need stabiliser hitch." is in my
experience a gross oversimplification.

Think we'll have to agree to disagree - but I'd like to know of
examples where these guidelines were met, but the rig was still
unstable.

My '89 Dodge Caravan and ASH 26 E trailer meets all your rules and is
stable at 60 mph. At 70 mph, it's starting to quiver, and I've never
dared go faster. So, is the rig "stable" or "unstable"?

What's the speed limit for a towing vehicle in the US? In the UK it's
60, so your rig would be "stable", though of course it would be
preferable to have a higher safety margin in the event of cross-winds
etc.

Let me try and explain this another way:

*if your trailer is trying to lift the rear of your tow vehicle when
hitched, it will have reduced stability than if it's pressing down.

*If your trailer has a heavy mass at the far end, it will have reduced
stability compared to if it had that mass in low down over the axle.

*If your trailer has underinflated tyres, it will have reduced
stability compared to if it had correctly inflated tyres (and they
might go "bang", too)

*If your trailer weighs more than your towcar, it will have reduced
stability compared to if the towcar was heavier than the trailer.

I hope that's clearer. The Bath University guidelines were also
developed using average Euro cars - I would not expect an tall,
unstable American SUV or pickup with ancient suspension to be
particularly stable in many circumstances, even when not towing. More
recent models with relatively modern suspension should, of course,
fare better.


Dan


On our USA Interstate Highways, speeds tend to average 75mph. Speed limits
are lower, but not usually enforced until above 80 mph or more. Even the
Semi trailers (18 Wheel trucks) are doing 70-75 or more. If you drive 65,
you are continually passed by these trucks, each producing "bow waves" that
induce more sway. So stability up to 80 mph is highly desirable.

The above noted points all contribute to stability, but I tried them all,
and then some, one at a time, and in combinations. There was no dramatic
improvement until I changed vehicles. The Tahoe and the Avalanche weigh
about the same. The Avalanche has a longer wheelbase. They both have live
rear axles and use the same tires.

IMO the best way to improve a tow vehichle is with "helper springs" to
stiffen the rear, and if needed, the front, suspension. These are easy to
add, relatively inexpensive, and can improve the handling even without the
trailer. Of course, this is after bringing the suspension up to "specs"
first. Shortening the distance between the hitch and the rear axle, where
possible, helps too. Two inches can make a difference.


Hartley Falbaum
"KF" USA

Regarding safety in collisions:

Linked bellow is a report from the institute for Highway safety that
shows that a car colliding with a heavy SUV favors the occupants of
the SUV enormously. These are death statistics.

However, in Solo acciddents, like spin outs and collisions with
immovable objects, the car is far better and the statistics support
this.

Because in cars, 42% of deaths are in solo accidents. In SUVs, 63% of
deaths are in solo accidents. So basically, don't loose control of an
SUV or hit anything. In cars, only 27% of deaths occur when cars are
involved with something bigger than themselves, including buses.

The report concludes that by far, the most deaths occur in solo
crashes in both cars and SUVs. This speaks against SUVs being safer
overall.

Overall, except for slow city driving, I doubt the SUV is safer and I
personally don't feel safer in one cruising on a country road or
freeway, especially towing something.

Report:
http://www.iihs.org/sr/pdfs/sr4005.pdf

Dan G wrote:

My '89 Dodge Caravan and ASH 26 E trailer meets all your rules and is
stable at 60 mph. At 70 mph, it's starting to quiver, and I've never
dared go faster. So, is the rig "stable" or "unstable"?

What's the speed limit for a towing vehicle in the US?

The highest speeds are on the Interstates. In California, it's 55 mph;
in Montana, it's 75 mph. Other states are between these two.

In the UK it's
60, so your rig would be "stable", though of course it would be
preferable to have a higher safety margin in the event of cross-winds
etc.

So, the study investigated relatively short, wide, and tall trailers
towed no faster than 60 mph. It doesn't seem likely to have much to
offer the typical glider pilot!

The point I'm trying to make is most of the glider towing combinations
can go fast enough to become unstable, and following the "rules" doesn't
ensure stability at even legal speeds, much less at the speeds many
pilots want to tow.



Let me try and explain this another way:

*if your trailer is trying to lift the rear of your tow vehicle when
hitched, it will have reduced stability than if it's pressing down.

*If your trailer has a heavy mass at the far end, it will have reduced
stability compared to if it had that mass in low down over the axle.

*If your trailer has underinflated tyres, it will have reduced
stability compared to if it had correctly inflated tyres (and they
might go "bang", too)

*If your trailer weighs more than your towcar, it will have reduced
stability compared to if the towcar was heavier than the trailer.

I think we all agreed from the start that the "rules" were sensible;
what some of us have pointed out is they are not sufficient. If pilots
never towed over 60 mph, we'd have far fewer trailer towing discussions!
And a lot fewer accidents, too.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

I tow with a Toyota 4-Runner which is a mid sized SUV. While it would
appear to be a good choice for towing I found 60 to be the limit
before sway would start. I believe the problem is that even though it
has fairly heavy suspension you can still induce sideways movement by
pushing with one finger on the rear of the vehicle. After trying every
solution I could think of I finally changed the trailer connector to
Al-Ko AKS 1300 Stabilizer, which works by pad pressure to the ball.

http://tinyurl.com/yvjhve


Towing is now stable up to the max speed of the vehicle, which with a
6 cylinder engine and trailer in tow is 85. While pricey at $250 for
the connector and special ball coupler it is cheaper than unwrapping
the car/trailer from a tree.

wrote:
After trying every
solution I could think of I finally changed the trailer connector to
Al-Ko AKS 1300 Stabilizer, which works by pad pressure to the ball.

http://tinyurl.com/yvjhve


Towing is now stable up to the max speed of the vehicle, which with a
6 cylinder engine and trailer in tow is 85. While pricey at $250 for
the connector and special ball coupler it is cheaper than unwrapping
the car/trailer from a tree.

Still cheaper than changing tires and wheels on the trailer or the
4-Runner, buying a new vehicle, or moving the axle back on trailer! And,
as I recall from your article, quite compact and easy to use compared to
the chains and springs of the load distribution solutions.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

You guys are leaving out a very important part of the equation when it
comes to stability and the ability to prevent sway. That would be
tires and the stiffness of their sidewalls. This makes a huge
difference. This can have as much of an impact as suspension.

Case in point; My brother and I at one time both had Dodge Ram trucks.
I had "E" rated tires, and he had really low rated tires (can't
remember which load designation). One of my trailers is a large 4-
place enclosed snowmobile trailer. We hitched it up to his truck to
head north for some snowmobiling and that rig was all over the place.
Glad the trailer had electric brakes because he had to apply them a
number of times to get the sway under control. Well, it wasn't very
many miles of this adventure before we turned back to switch to my
truck. When we got back from the trip, he replaced all of his tires
with a higher load range (don't remember if he went all the way to
"E") and we took a test drive with the trailer. The difference was
night and day. Problem solved!

Some of you guys with sway issues should see your tire dealer and
inquire about stiffer tires. Granted, the ride is not quite as soft,
but it's a lot safer. Even when you're not towing.


Cheers,
Dave

On Oct 17, 3:02 pm, wrote:
You guys are leaving out a very important part of the equation when it
comes to stability and the ability to prevent sway. That would be
tires and the stiffness of their sidewalls. This makes a huge
difference. This can have as much of an impact as suspension.

Case in point; My brother and I at one time both had Dodge Ram trucks.
I had "E" rated tires, and he had really low rated tires (can't
remember which load designation). One of my trailers is a large 4-
place enclosed snowmobile trailer. We hitched it up to his truck to
head north for some snowmobiling and that rig was all over the place.
Glad the trailer had electric brakes because he had to apply them a
number of times to get the sway under control. Well, it wasn't very
many miles of this adventure before we turned back to switch to my
truck. When we got back from the trip, he replaced all of his tires
with a higher load range (don't remember if he went all the way to
"E") and we took a test drive with the trailer. The difference was
night and day. Problem solved!

Some of you guys with sway issues should see your tire dealer and
inquire about stiffer tires. Granted, the ride is not quite as soft,
but it's a lot safer. Even when you're not towing.

Cheers,
Dave

Absolutely. Look back to an earlier post on towing. When I switched
to a cheaper, lower speed rated tire to save some money on my tow
vehicle (VW Passat wagon), the tow stability was noticably worse.
Upgrading to better tires (similar to the OEM values) immediately got
me back to where I used to be, which was a stable tow at up to about
70 mph.

P3

I agree with Dave. Heavier sidewalls, which are higher load rated not
higher speed rated, will help since they are more resistant to lateral
movement. Problem is that after an expensive tire change you may still
end up with some sway but in addition a car that rides like a gravel
truck.

I agree with Dave. Heavier sidewalls, which are higher load rated not
higher speed rated, will help since they are more resistant to lateral
movement. Problem is that after an expensive tire change you may still
end up with some sway but in addition a car that rides like a gravel
truck.