Driving over corrugations

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Duncan_Uda
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Driving over corrugations

Unread post by Duncan_Uda » July 11th, 2010, 9:03 pm

Hey everyone

I live in Botswana and a fellow 4x4 fenatic.

I just returned from an off-road trip and need your thoughts on an argument I had with several of the drivers that were in the convoy.

We drove over almost 100km of corrugations.

I have been into 4x4ing over 20 odd years and my training has been "do not drive fast over corrugations". The reasoning behind this is, if you drive fast, the ride becomes more bearable, but your wheels have very little traction as they skim over the corrugations. So I always keep my driving to a slow controlable speed. My be uncomfortable, but safe.

However, during this trip, the convoy leader adviced otherwise and almost all the drivers "flew" over the corrugations.

I still stand by my argument.

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ERASER
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Unread post by ERASER » July 11th, 2010, 9:13 pm

Drive at a speed that smooths the corrugations out, as long as the conditions your driving in permits it of cause.

Duncan_Uda
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Unread post by Duncan_Uda » July 11th, 2010, 9:23 pm

I agree ERASER.....

Let me add some more details, most 4x4s were carrying at least 800kgs (excluding the passengers). Some were pulling trailers.

Most were top heavy with roof top tents, jerry cans, gas bottles, roof mounted shower water tanks, etc.

At times most were hitting 120+ km/h. Too fast in my opinion.

The road we drove on is used by heavy commercial vehicles so you can imagine the corrugations they cause.

ERASER
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Unread post by ERASER » July 11th, 2010, 9:35 pm

Top heavy, 120km/h, 800kg's of extra weight on roads with corrugations! Way to fast. Id be finding others to drive with before these guys kill themselves or someone else. What happens if one of them had to swerve? What happens if they hit a soft patch? What happens if a tyre blows?

cac
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Unread post by cac » July 11th, 2010, 9:45 pm

i agree in principle that driving faster over corrugations makes it more comfortable, but prefer to stay under 80km/hr or so on the dirt...

letting a few psi out of the tyres would also help make the ride more bearable, without having to increase your speed...
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Timber
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Unread post by Timber » July 11th, 2010, 10:04 pm

Duncan_Uda wrote:I agree ERASER.....

Let me add some more details, most 4x4s were carrying at least 800kgs (excluding the passengers). Some were pulling trailers.

Most were top heavy with roof top tents, jerry cans, gas bottles, roof mounted shower water tanks, etc.

At times most were hitting 120+ km/h. Too fast in my opinion.

The road we drove on is used by heavy commercial vehicles so you can imagine the corrugations they cause.

Please don't take offence, but I think this must be some kind of leg pulling. Noone in their right mind would hit corrugation with that kind of speed, unless of course they have a death wish, damned good way to lose control and be killed, but then what do I know, only driven rough roads all my life.

With trailers and variously spread weight, drop your tyre pressure, pick your track carefully, and get those jerry cans and gas bottles off the roof. Spread the weight evenly so that your suspension takes it more evenly. Hey, I am obviously a novice, someone here may know better.
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legendbeast
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Unread post by legendbeast » July 11th, 2010, 10:28 pm

120km/h is good going, sure would be exciting! I'd prefer to do it a bit slower and to make the ride more comfortable drop your tyres down a bit. I usually run mine on the highway at 40 when i get on the dirt if i can be bothered i drop them to 30 much better ride. If the corrogations are real bad like a few times i've been around ill drop them low 20's. Makes a huge difference to comfortability.
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AUSJohn
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Unread post by AUSJohn » July 11th, 2010, 11:24 pm

Id believe 120. Ive been overtaken as if i was parked while doing 50 on a beach.

Never under-estimate the stupidity of man.

nilla60
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Unread post by nilla60 » July 11th, 2010, 11:45 pm

120 km/h on bad roads was normal work fun for a friend of mine who was doing mining exploration when he was young and indestructible. He kept promising to send me pics of two 75s scant inches apart when traveling at 100+ but was usually preoccupied driving to whip out the camera.

Dr Karl, a popular science journalist here did a lot of study about them many years back, we're apparently the world experts on corrugated roads:
Karl Trek -Corrugated Roads Revisited

I find that good springs and even better shock absorbers are the biggest difference in safe and comfortable corrugation driving. The factory Toyota springs are particularly poor (40, 60, 75). I find 80 km/h is usually enough to smooth things out. Anyone driving corrugations without good shocks will trash their truck or end up in the ditch.

Timber
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Unread post by Timber » July 11th, 2010, 11:50 pm

nilla60 wrote:120 km/h on bad roads was normal work fun for a friend of mine who was doing mining exploration when he was young and indestructible. He kept promising to send me pics of two 75s scant inches apart when traveling at 100+ but was usually preoccupied driving to whip out the camera.

Dr Karl, a popular science journalist here did a lot of study about them many years back, we're apparently the world experts on corrugated roads:
Karl Trek -Corrugated Roads Revisited

I find that good springs and even better shock absorbers are the biggest difference in safe and comfortable corrugation driving. The factory Toyota springs are particularly poor (40, 60, 75). I find 80 km/h is usually enough to smooth things out. Anyone driving corrugations without good shocks will trash their truck or end up in the ditch.

Could not agree with you more Nilla. That is why I have OME shockies all round, an OME RTC Stabiliser, and 400kg Rockcrawler springs on the back, with 50mm shackles and greasable pins. Mind you, I have still had Shockie bolts vibrate out, then the kangaroo hops start.
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Duncan_Uda
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Unread post by Duncan_Uda » July 12th, 2010, 11:03 pm

@ Timber

This is not a leg pulling (and no offence taken). I have been off roading for close to 25 years and take it quite seriously. Would not make fun of things such as this.

It sounds hard to believe, but this is how these guys were. to get there as soon as possible. I certainly will not travel with them again. Though I must admit once in camp they were a fun bunch.

Sadly it is this sort of driving that gives the rest of us a bad name.

steveandviv
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Unread post by steveandviv » July 12th, 2010, 11:35 pm

I find that for most corrugations 72K is perfect towing our camper for EG, the Tanamia. But you can't just say 1 speed is OK, you have to look at the conditions. If the track allows for a bit of speed where you can get the *skip* going on then well and good. Can't do that going into the Bungles or Hallagan Bay. Then you need to access your speed. With out a doubt most people who do not know go to slow. I'm not saying go 100 - I'm saying 20 K is to slow on the Plenty. 65 K was great on the Merrinie Loop

At the end of the day there are to many variables to be telling someone how fars or slow to go, you need to read the conditions and drive to that.
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Mitcon
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Unread post by Mitcon » July 13th, 2010, 8:05 am

I'm with the others, sounds way too dangerous. Heck as a rule I never go more than 70kph on unsealed roads, if I hit really rough sections I drop pressures a bit more and keep an eye on tyre temps.

Driving faster over these kind of roads just makes them worse too IMO
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Unread post by Jackaroo-Smith » July 13th, 2010, 1:10 pm

120km/h! no way i could do that......don't think the old jackaroo could even go that fast

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Unread post by big bear » July 13th, 2010, 2:23 pm

i try and do a minimum of 80 km/h on the dirt tracks up here , mind you my old cruiser would be lucky to reach that on a dirt road with a loaded trailer on and i am generally on the same tracks all the time so you know when to slow down for big holes and bad corners , and i almost never have a trailer on.

I've got a Ford RTV Ute and i happily sit on 120 down dirt tracks regularly , mind you they are tracks i know well and it's not exactly a loaded up tourer and i slow down whenever i see another vehicle because im not ignorent enough to dust oncoming traffic out.

To much wear and tear on the vehicle on bad corrugations doing less than 70 , there'd be nothing left of me poor old crusier if i did that ! hahaha
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