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David K
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Okay, so you quoted a Euro link about what is NOT causing washboard... Why did you leave out what DOES cause it (if not the shocks/ tires tyres)?
[Edited on 6-8-2011 by David K]
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mtgoat666
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| Quote: | Originally posted by David K
Okay, so you quoted a Euro link about what is NOT causing washboard... Why did you leave out what DOES cause it (if not the shocks/ tires tyres)?
[Edited on 6-8-2011 by David K] |
ok, in simpler words, the experiments found the following:
Granular materials of unpaved roads are are inherently unstable.
According to McElwaine, ripple formation begins because no road surface is perfectly flat. When a wheel encounters a random hump in the road, it rises
up and falls back down, pushing a bit of material out of its way to create a trough and a second hump. Subsequent wheels continue this process and a
pattern of regular humps and troughs emerges.
The researchers found that the wheel typically caused a small single ripple to form at one location in the sand after about ten or so rotations of the
table. New ripples then grew rapidly from the single ripple and spread until the entire path of the wheel was covered in ripples.
The experiment was repeated using a different type of sand and again using long-grain rice. ...the researchers discovered that changing materials had
little effect on ripple formation – suggesting that washboards cannot be avoided by using a specific type of material in road construction.
Indeed, the experiments and related computer simulations revealed that ripple formation is governed only by the speed of the wheel, its weight per
unit width and the density of the granular material. Ripples were not seen when the wheel was kept below a critical speed – about 8 km/h for a car –
leading the team to conclude that at higher vehicular speeds a flat road is unstable and will quickly become rippled.
The study also suggests that heavier wheels will produce smaller ripples because their greater mass inhibits the vertical motion required to make a
washboard.
=================
perhaps if y'all stayed below 8 k/hr there would be no washboards. Or if y'all drove really heavy vehicles, the washboards would be smaller and
perhaps more comfortable.
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David K
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Thank you!
So, washboarding is unavoidable unless we stay under 5 mph or drive motorhomes (or tanks)...
It does say the wheel rising up and down is the cause... so in a way, bad shocks (which allow excessive verticle wheel travel) make things worse,
quicker than those with good shocks... but that all car travel (over 5 mph) will form washboard ripples.
[Edited on 6-9-2011 by David K]
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Udo
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I'll go with Ron's anwer:
4-20-40, sometimes 60...the FJ Cruiser handles pretty good at 60!
Udo
Youth is wasted on the young!
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TMW
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Here is some more info:
Physics of Washboard Road Formation
Stockbyte/Getty Images
The wheels of a vehicle push back dirt, and over time that dirt builds up into small ridges.
Some experts who maintain dirt roads say that your car's suspension system causes the problem as it actually tries to smooth out the bumps in the road
[source: U.S. Forest Service]. As a wheel moves over a bump, the suspension system absorbs the shock and then pushes back against the road surface. On
a soft surface like a dirt road, the push back either packs or displaces the dirt it hits. Over time, as more and more cars go over the bump, the
washboard pattern develops.
However, in the summer of 2009, physicists from Canada, France and the United Kingdom published a new study about the physics of washboard road
formation. They discovered that ripples will form, even when the springy suspension of a car and the rolling shape of a wheel are eliminated [source:
American Physical Society].
They built an experimental vehicle, replacing the wheel with a suspension rolling over a road with a simple inclined plow blade, without any spring or
suspension, dragging over a bed of dry sand. Ripples appear when the plow moves above a certain speed.
After observing the results, they compared this phenomenon to the physics of stone skipping: A stone needs to be thrown above a specific speed in
order to have enough force to bounce of the surface. A washboarding plow is similar, except the sandy surface remembers its shape and the effect is
amplified.
They concluded that the formation of a washboard pattern is inevitable. The ridges will form, even if the wheel diameter, suspension or surface is
changed. The only way to avoid the effects of a washboard road is to stay below a certain speed, but that's impractical: you'd usually have to drive
at 3 miles per hour (4.83 kilometers per hour) to eliminate the problem altogether.
Some day, such discoveries may lead to improved suspension systems or improved road surfaces that smooth out a bumpy ride. In the meantime, there's
not much you can do about washboard road except brace yourself, watch your speed and hang on for the ride.
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mtgoat666
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american researchers lagging in important fields of science!
| Quote: | Originally posted by TW
However, in the summer of 2009, physicists from Canada, France and the United Kingdom published a new study about the physics of washboard road
formation. They discovered that ripples will form,... |
TiddlyWinks:
and that's what is posted above 
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durrelllrobert
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WHAT WASHBOARDS?
Not a Problem:
Bob Durrell
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mondo
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Air down helps a lot. We have a 2500 Dodge Diesel 4x4. Nornal psi is 65 but we go down to 30psi for the run to Gonzaga Bay. The truck has a motorcyle
and basic camping stuff. We run at 15 to 30 mph most of the time. Comfort and safty more important than speed for us.
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redhilltown
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I also air down quite a bit and of course it not only helps for comfort but for punctures etc. The only problem is in Baja, unless you have your own
way to air back up it can be a while on the highway which is not good for your tires nor your safety. There was a thread not too long ago about air
compressors (for the most part the small -plug- into- your -battery ones are crap)....David K had one he really likes and my friend I adventure with
has a spectacular one that hooks up to your battery and takes about 10 mins total for all four tires...I should know the name of it, shouldn't I!!!
And at least here in the states, I'm sure many of us have horror stories of trying to air back up at a gas station...feeding in tokens or quarters in
the freezing cold for a machine that couldn't pump up a bicycle tire on a good day.
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Cypress
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Washboard roads are the result of harmonic oscillation.
[Edited on 6/13/2011 by Cypress]
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BajaGringo
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| Quote: | Originally posted by redhilltown
I also air down quite a bit and of course it not only helps for comfort but for punctures etc. The only problem is in Baja, unless you have your own
way to air back up it can be a while on the highway which is not good for your tires nor your safety. There was a thread not too long ago about air
compressors (for the most part the small -plug- into- your -battery ones are crap)....David K had one he really likes and my friend I adventure with
has a spectacular one that hooks up to your battery and takes about 10 mins total for all four tires...I should know the name of it, shouldn't I!!!
And at least here in the states, I'm sure many of us have horror stories of trying to air back up at a gas station...feeding in tokens or quarters in
the freezing cold for a machine that couldn't pump up a bicycle tire on a good day. |
This is the one I use and really like. I did find it at a better price...
Warn Air Compressor
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durrelllrobert
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| Quote: | Originally posted by Cypress
Washboard roads are the result of harmonic oscillation.
[Edited on 6/13/2011 by Cypress] |
 :lol f
course:
www.youtube.com/watch?v=l2xOw-VXe_g
Bob Durrell
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David K
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| Quote: | Originally posted by redhilltown
I also air down quite a bit and of course it not only helps for comfort but for punctures etc. The only problem is in Baja, unless you have your own
way to air back up it can be a while on the highway which is not good for your tires nor your safety. There was a thread not too long ago about air
compressors (for the most part the small -plug- into- your -battery ones are crap)....David K had one he really likes and my friend I adventure with
has a spectacular one that hooks up to your battery and takes about 10 mins total for all four tires...I should know the name of it, shouldn't I!!!
And at least here in the states, I'm sure many of us have horror stories of trying to air back up at a gas station...feeding in tokens or quarters in
the freezing cold for a machine that couldn't pump up a bicycle tire on a good day. |
For sure you should not air down unless you have a pump!!!
The cig. lighter connect ones are very slow, about 2 psi per min.
The battery clip ones are about 3 times faster (6 psi per minute). I got one at Harbor Freight in 2006 for $49 (on advice from bajalou).
Recently, I was given one that is almost the same, but stores in a smaller bag instead of a hard plastic case. It pumped 5 psi per minute. It is a
Master Flow Tsunami (model MF-1050).
[Edited on 6-13-2011 by David K]
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redhilltown
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| Quote: | Originally posted by David K
| Quote: | Originally posted by redhilltown
I also air down quite a bit and of course it not only helps for comfort but for punctures etc. The only problem is in Baja, unless you have your own
way to air back up it can be a while on the highway which is not good for your tires nor your safety. There was a thread not too long ago about air
compressors (for the most part the small -plug- into- your -battery ones are crap)....David K had one he really likes and my friend I adventure with
has a spectacular one that hooks up to your battery and takes about 10 mins total for all four tires...I should know the name of it, shouldn't I!!!
And at least here in the states, I'm sure many of us have horror stories of trying to air back up at a gas station...feeding in tokens or quarters in
the freezing cold for a machine that couldn't pump up a bicycle tire on a good day. |
For sure you should not air down unless you have a pump!!!
The cig. lighter connect ones are very slow, about 2 psi per min.
The battery clip ones are about 3 times faster (6 psi per minute). I got one at Harbor Freight in 2006 for $49 (on advice from bajalou).
Recently, I was given one that is almost the same, but stores in a smaller bag instead of a hard plastic case. It pumped 5 psi per minute. It is a
Master Flow Tsunami (model MF-1050).
[Edited on 6-13-2011 by David K] |
Well after seeing this and looking them up the best I can on the google, I finally bought this very model today at Pep Boys. The reviews were very
positive except the need to tweak it a bit. I will be deep into the Inyo mountains and Saline Valley this weekend and I will give a report (not what
this thread is really about I realize, but why not?).
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mtgoat666
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| Quote: | Originally posted by Cypress
Washboard roads are the result of harmonic oscillation.
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are you sure?
| Quote: | Originally posted by Cypress
harmonic oscillation.
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do you even know what those two words mean?
[Edited on 6-23-2011 by mtgoat666]
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Cypress
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Yep!
[Edited on 6/23/2011 by Cypress]
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redhilltown
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| Quote: | Originally posted by David K
| Quote: | Originally posted by redhilltown
I also air down quite a bit and of course it not only helps for comfort but for punctures etc. The only problem is in Baja, unless you have your own
way to air back up it can be a while on the highway which is not good for your tires nor your safety. There was a thread not too long ago about air
compressors (for the most part the small -plug- into- your -battery ones are crap)....David K had one he really likes and my friend I adventure with
has a spectacular one that hooks up to your battery and takes about 10 mins total for all four tires...I should know the name of it, shouldn't I!!!
And at least here in the states, I'm sure many of us have horror stories of trying to air back up at a gas station...feeding in tokens or quarters in
the freezing cold for a machine that couldn't pump up a bicycle tire on a good day. |
For sure you should not air down unless you have a pump!!!
The cig. lighter connect ones are very slow, about 2 psi per min.
The battery clip ones are about 3 times faster (6 psi per minute). I got one at Harbor Freight in 2006 for $49 (on advice from bajalou).
Recently, I was given one that is almost the same, but stores in a smaller bag instead of a hard plastic case. It pumped 5 psi per minute. It is a
Master Flow Tsunami (model MF-1050).
[Edited on 6-13-2011 by David K] |
Well it worked like a charm! Thanks DK. Got it at Pep Boys and while the price said 79.99 when she rang it up it was 55.00...plus I found a five
dollar bill in the parking lot so let's just call it 50.00!!! Canvas case is a piece of crap (is there not ONE person out of a billion that can make
a proper zipper in China?) and I will replace it but other than that, no complaints. I didn't really need to air down but I wanted to check it out so
I went down to 25 psi and it brought each tire back up in about two minutes max. One of the main complaints on the units is the pressure gauge is off
but this one was pretty accurate. Let's just say it was a PERFECT beer break! And on a Baja note I cooked up a whole L.A. Bay Goldspotted Bass from
last fall on the campfire...even after that long of time it was delicious...freezer wrap and double bagged did the trick.
The only true problem is I am now out of Goldspotted Bass...
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