Do trailers with coil springs and shock absorbers sway at higher speeds?

On Friday, June 13, 2014 8:57:25 AM UTC-6, son_of_flubber wrote:
That said, a two-wheel drive full size van tempts me.

Like this one?

http://gallery2.jpmullan.com/v/scans...myvan.jpg.html

On Friday, June 13, 2014 7:57:25 AM UTC-7, son_of_flubber wrote:
On Friday, June 13, 2014 12:23:47 AM UTC-4, Frank Whiteley wrote:



You're coming out west? Mountain passes in Colorado top 10,000 MSL. Snow recently on Berthoud pass for the Ride the Rockies Bicycle Tour. Wyoming and New Mexico not so bad. Montana's okay also. Arizona, Flagstaff to Tucson is interesting, both ways. Bring range, horsepower, and all or 4WD. Nevada and California are okay. Idaho, Washington, and Oregon are mostly easy. The Pendleton grade is fun, both ways, and interesting on ice. I'm presuming summer travel. Winter is a bit different when I'd recommend a big tow vehicle option.





Frank Whiteley



The earliest that I would tow my glider out west would be 2016. Getting ready now to tow from Vermont to Florida in Nov 2014 and back to Vermont in 2015.



Bring range, horsepower, and all or 4WD.



My 2004 Volvo XC70 has all of that, highish ground clearance, comfortable seats and a 'safety cockpit'. It is a light truck trapped in a station wagon body (with a low CG compared to most light trucks/SUVs). That said, a two-wheel drive full size van tempts me.

You never said what kind of tires you have on the trailer. Use ONLY trailer rated tires (they have stiffer sidewalls than car tires). As recommended previously, check alignment by measuring the distance from the ball to both wheel axles. Look at tire wear for signs of misalignment (uneven wear, scallops). Replace the tires if more than 4 years old. Believe me, a tire blowout at 75 mph is no fun and will likely cost you an extra day. Make sure you have a good spare, btw. Anti-sway friction devices are a bandaid and should be used only as a last resort (and reduce your speed: trailer towing upsets can, and have been, fatal). Measure (don't guess) your tongue weight. It should be a MINIMUM of 5% of the trailer weight, and closer to 10% (that will be 150 to 200 lbs!). You may have to add air shocks to your tow vehicle to support this weight (which is easy to do).

Your vehicle should be able to tow your trailer at all legal highway speeds, so something else is wrong.

Tom

On 14-Jun-14 00:57, son_of_flubber wrote:
On Friday, June 13, 2014 12:23:47 AM UTC-4, Frank Whiteley wrote:
....
Bring range, horsepower, and all or 4WD.

My 2004 Volvo XC70 has all of that, highish ground clearance,
comfortable seats and a 'safety cockpit'.

No, it doesn't. Karl gave the 2 main rules and the XC70 doesn't follow
either.

It is a light truck
trapped in a station wagon body (with a low CG compared to most light
trucks/SUVs).

1. I haven't measured it but my eye tells me that there is too big a
distance from the towball to the axle - because of its station wagon
heritage.

2. It's too light. TINSFOM - there is no substitute for mass. My 4WD
is 2.2 tonnes and doesn't take crap from glider trailers.

GC

On Sunday, June 15, 2014 8:01:30 AM UTC-6, GC wrote:
On 14-Jun-14 00:57, son_of_flubber wrote:

On Friday, June 13, 2014 12:23:47 AM UTC-4, Frank Whiteley wrote:

...

Bring range, horsepower, and all or 4WD.



My 2004 Volvo XC70 has all of that, highish ground clearance,

comfortable seats and a 'safety cockpit'.



No, it doesn't. Karl gave the 2 main rules and the XC70 doesn't follow

either.



It is a light truck

trapped in a station wagon body (with a low CG compared to most light

trucks/SUVs).



1. I haven't measured it but my eye tells me that there is too big a

distance from the towball to the axle - because of its station wagon

heritage.



2. It's too light. TINSFOM - there is no substitute for mass. My 4WD

is 2.2 tonnes and doesn't take crap from glider trailers.



GC

There is a test for tow vehicle suitability. Just push the rear of the tow vehicle sideways with your hands in a rhythmic manner until you find its natural resonant frequency. My old Jeep Grand Cherokee's resonant sway exactly matched my Komet trailer's - no wonder the rig would weave all over the highway above 65MPH.

My theory is every tow vehicle/trailer rig is dynamically unstable above some speed. All one can hope to do is try to raise that speed high enough it isn't a practical limitation - then never exceed that speed.

....and if you live somewhere warm don't buy cheap Chinese trailer tires - they are made from a low melting point mystery plastic!

Mike

Mike the Strike wrote, On 6/11/2014 6:17 AM:
My 2001 Cobra trailer arrived from the previous owner with lead
weights and dumbbells at the front to increase tongue weight. I
removed them and found still plenty of tongue weight and no towing
instability behind a Toyota 4Runner at speeds up to 85 mph (Arizona
highway speed!) I replaced the tires last year with recommended
trailer tires and have absolutely no problems except in very strong
gusty side-winds, when I slow to 70 mph.

Gulp! _Slow_ to 70 mph? Better check the speed rating on those ST
trailer tires, because the standard rating is only 65 mph! Some ST tires
are rated up to 75 mph, using different load inflation charts (generally
requiring much higher inflation pressures) than the normal ST tires.
Those stiffer sidewalls people like to talk about are intended for
stability, and the tradeoff is they heat up more easily.

Most people don't realize how different ST (trailer tires) from other
tires. They are not "stronger" passenger car tires, or even "stiffer"
light truck tires. They are designed for a specific purpose that is
quite different than car and truck tires.

If you want to tow your trailer at 85 mph, you better get LT (light
truck) tires with the appropriate speed rating (I'd use a speed rating
of at least 100-110 mph), and be sure you have them at the correct pressure.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl