Corrugations, what causes them?

Submitted: Wednesday, May 14, 2003 at 00:06
ThreadID: 4901 Views:1693 Replies:10 FollowUps:7
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I would like to hear the opinions of other people. Some friends say the effects of suspension etc but why is the ripple in the same shape in either direction and why is it across the whole road? Why are some areas closely spaced and others further apart?


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Reply By: Member - Chris (W.A.) - Wednesday, May 14, 2003 at 01:14

Wednesday, May 14, 2003 at 01:14
I was "accused" of it because of my full - time 4x4 cruiser. If that's true, everybody get used to it because it's not going to change.
haha.Love the bush.
Chris
AnswerID: 19964

Reply By: Eric from Cape York Connections - Wednesday, May 14, 2003 at 07:42

Wednesday, May 14, 2003 at 07:42
Slammin I get asked that question evey season in the cape and the answer is ............................................................................................................................................................ !!!!!!!!!!!!!!!!!!!!!!!!!!!! .
All the best
EricCape York Connections
AnswerID: 19968

Reply By: Member - Bob - Wednesday, May 14, 2003 at 08:19

Wednesday, May 14, 2003 at 08:19
This was extensively discussed on one of the forums about a year ago. Even one of the unversities had don quite a lot of research which was quoted. The cause, if you are a regular reader of this forum you will already know, is......














...... selfish bastards towing trailers ;-) Seriously though, do a search and you will find a lot of stuff.
AnswerID: 19970

Reply By: StephenF - Wednesday, May 14, 2003 at 09:33

Wednesday, May 14, 2003 at 09:33
Have a look at http://www.abc.net.au/science/k2/trek/default.htm

Stephen.
AnswerID: 19979

Follow Up By: Member - Wherethefugawi - Wednesday, May 14, 2003 at 09:41

Wednesday, May 14, 2003 at 09:41
went there but i'm still none the wiser lolRichard
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Reply By: Member - Bob - Wednesday, May 14, 2003 at 10:33

Wednesday, May 14, 2003 at 10:33
See Colin's post of May 29 2002.
AnswerID: 19986

Reply By: Rob from Cairns Offroad Training & Tours - Wednesday, May 14, 2003 at 11:07

Wednesday, May 14, 2003 at 11:07
Look on the bright side, imagine how boring the trip would be without corrogations. I had a deep and meaningful conversation about this around the campfire with a friend who travels the Cape regularly. He reckons the corros are getting taller, sharper and further apart due to more coil spring vehicles using the road. Corros are there like the sun in the sky, who knows, who cares, why worry. Good shocks and springs, lower tire pressure and less speed, no problem.
Cheers Rob.
Cairns Offroad Training & Tours
www.4wdtraining.com
4wdtraining@cairns.net.au
www.cedarparkresort.com.au

Cairns Offroad Training & Tours
AnswerID: 19991

Follow Up By: Tuco69 - Wednesday, May 14, 2003 at 12:45

Wednesday, May 14, 2003 at 12:45
"lower tire pressure and less speed"

Hi Rob - sure is hard to convince the majority, that droping their tyre pressures on the dirt will lead to a better ride, more control and less tyre fractures .... I'm with you on this one.

Tuco in Cairns
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FollowupID: 12739

Follow Up By: Goona - Monday, May 19, 2003 at 19:36

Monday, May 19, 2003 at 19:36
Guys what pressures are you running fully loaded on the corrogations.
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Follow Up By: Tuco69 - Monday, May 19, 2003 at 22:07

Monday, May 19, 2003 at 22:07
Normally 32 PSI on the bitumen, 25 PSI on the dirt (corrugations) and 15 PSI on the sand.

Tuco in Cairns
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FollowupID: 13128

Reply By: Member - Peter (WA) - Wednesday, May 14, 2003 at 17:36

Wednesday, May 14, 2003 at 17:36
PETERS BELEAVE IT OR NOT
As Australia was once completly covered by the ocean a few thousand years ago ,the Corrugations are the result of the wave formations coming to the surface once the top soil has been eroded away by the parade of 4WDs on the track, this is why the more popular the track the bigger the corrugations and if you stop and look very carefully between the corrugations you will find small sea shells .If you look skyward at set times you will see pigs flying.LOL
Now how is that for a differant slant on an age old questionBorn to drive a 4x4 , not a keyboard
Peter York 4x4
AnswerID: 20046

Reply By: Member - Russell - Wednesday, May 14, 2003 at 19:59

Wednesday, May 14, 2003 at 19:59
I figure they start with the vehicle wheel hitting a rock, stick, or something which makes the wheel bounce. As it bounces several times, it starts the up and downy stuff. Lots of vehicles, lots of bouncing, lots of up and downy stuff that loosen your teeth etc. Pitch might depend on speed, wheel diameter, road material soil type blah blah blah. Don't really know, but if we could just find that little rock that starts it all, we'd have no problem, right?Russell S
Prado RV6
AnswerID: 20059

Reply By: Treading Lightly - Thursday, May 15, 2003 at 09:37

Thursday, May 15, 2003 at 09:37
What a way to open a can of worms. It may be better to ask how did the moon get there, or who put the worms in the can.Life is to good to be dead.
AnswerID: 20102

Follow Up By: Member - Peter (WA) - Thursday, May 15, 2003 at 14:47

Thursday, May 15, 2003 at 14:47
WATTIES put the worms in a can with tomato sauce LOLBorn to drive a 4x4 , not a keyboard
Peter York 4x4
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Follow Up By: diamond(bendigo) - Thursday, May 15, 2003 at 20:22

Thursday, May 15, 2003 at 20:22
i might be wrong but it could be the worms from all the cans of worms we open here causing all the damage .just an idealooking foward to september(landcruiser park/fraser island)
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Reply By: Mike - Sunday, May 18, 2003 at 23:34

Sunday, May 18, 2003 at 23:34
I see you didn't get many "good" answers to your question. Let me take a stab:

Corrugations are all due to suspension harmonics.

For example - as your wheel goes over a bump it takes off and the wheel spins a little. The wheel then comes down. A set of corrugations starts with one. Your wheel jumps, the wheel spins, the wheel comes down, the wheel jumps, the wheel spins, the wheel comes down..etc etc.

What I've noticed is that the harmonics seem to be different for different vehicles. For example, the majority of corrugations are caused by Toyotas -them being the majority of vehicles on the road. If you've ever travelled over corrugations in a Landrover it seems to float over the top with less shaking - why? Because it has different suspension geometry and therefore harmonics than the vehicles that caused the corrugations.

The spacing and height of the corrugations equals a function of the vehicle speed, the travel of the suspension and the harmonics.

Have you also noticed how corrugations are particularly bad at the start of a hill of coming out of a corner - this is caused by harmonics again and the power applied to the rear wheel causes it to make a small indentation then the next vehicle makes it bigger and before you know it wheels are skiping up and down along the road - each vehicle makes the corrugations worse. The application of power makes the wheel spin at each jump even worse than normal flat driving.

So what can we do? Absolutely nothing (unless we all want to run tank tracks). Nature will always head towards chaos so we can't keep perfectly smooth roads. As soon as a small lump appears it will be the nucleus of a corrugation.

Happy bumpy driving!!!
AnswerID: 20393

Follow Up By: Member - Rohan K - Monday, May 19, 2003 at 09:38

Monday, May 19, 2003 at 09:38
Mike, if that the case (tojos being the route of all evil), why does my Nissan Pathfinder, find every corregation (and only some paths)? Its rear harmony is shocking - at least when the kids are going full-tonsil in the back.Be good, or be quick.
Rohan (Sydney)
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FollowupID: 13077

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