Guys, PLEASE!!! ALWAYS 4x4 on gravel





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  1. #1
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    Default Guys, PLEASE!!! ALWAYS 4x4 on gravel

    We visited Kgalagardi the last four weeks and travelled the roads (4x4 only tracks) extensively. The corrugations are teeth rattling and mostly due to people driving in 2x4.

    I know some will now start bitching about why 4x4 when 2x4 is OK. You just don't know.

    The track from Nossob to Bitterpan was an eye-opener for the uninformed. The vehicle in front of me was certainly travelling in 2x4 and was corrugating the soft sand to such an extent that I had to move off the line and try to keep on the shoulder. This is a tweespoor and 50km of it. The longer I travel the more the m0$r in I got. At some stage Trudie said she hopes that guy is not at Bitterpan.

    And he was!! An elderly guy who used to own a 200VX and recently swopped it for a LC Bakkie with an AHA top. He was travelling in 2x4 and quite proudly stated his truck did it without difficulty. When I explained what actually happened behind him in the track with the rear diff continuously throwing power from one wheel to the other to overcome the heavy drag that the front wheels are causing he was quite surprised. We actually took a stroll to the track entering the campsite and showed him his track and mine. Then he apologised profusely. He really did not know.

    This happens on ANY gravel road, whether slight or extensive and this is what is starting a corrugation immediately after a grading and gets worsened as wheels go over more and more.

    A rule should be that a 4x4- vehicle must ALWAYS be shifted to 4x4 (if not permanent) when on gravel. ANY GRAVEL.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Johan, I dont want to detract from your observations. My impression is that corrugations are caused (mainly) by similarity in wheel base of vehicles using the road and harmonic resonation of the suspension over time. This being the reason why some vehicles, at the right speed, dont find the corrugations as bad as others.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by JohanMaree View Post
    We visited Kgalagardi the last four weeks and travelled the roads (4x4 only tracks) extensively. The corrugations are teeth rattling and mostly due to people driving in 2x4.

    I know some will now start bitching about why 4x4 when 2x4 is OK. You just don't know.

    The track from Nossob to Bitterpan was an eye-opener for the uninformed. The vehicle in front of me was certainly travelling in 2x4 and was corrugating the soft sand to such an extent that I had to move off the line and try to keep on the shoulder. This is a tweespoor and 50km of it. The longer I travel the more the m0$r in I got. At some stage Trudie said she hopes that guy is not at Bitterpan.

    And he was!! An elderly guy who used to own a 200VX and recently swopped it for a LC Bakkie with an AHA top. He was travelling in 2x4 and quite proudly stated his truck did it without difficulty. When I explained what actually happened behind him in the track with the rear diff continuously throwing power from one wheel to the other to overcome the heavy drag that the front wheels are causing he was quite surprised. We actually took a stroll to the track entering the campsite and showed him his track and mine. Then he apologised profusely. He really did not know.

    This happens on ANY gravel road, whether slight or extensive and this is what is starting a corrugation immediately after a grading and gets worsened as wheels go over more and more.

    A rule should be that a 4x4- vehicle must ALWAYS be shifted to 4x4 (if not permanent) when on gravel. ANY GRAVEL.
    And then you get the cheapscates that doesn't think 4 wheel drive is necessary on soft gravel and drive the gravel everyday with a rear wheel drive or front wheel drive.....shocks don't last on corrugated roads....even shock mounts break....

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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    In my humble opinion, it is more a function of incorrect tire pressure and speed, than 2x4 vs 4x4

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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by Estee View Post
    Johan, I dont want to detract from your observations. My impression is that corrugations are caused (mainly) by similarity in wheel base of vehicles using the road and harmonic resonation of the suspension over time. This being the reason why some vehicles, at the right speed, dont find the corrugations as bad as others.
    Maybe so after the first corrugations were created, Estee.

    When you one day get the opportunity go ride on smooth sand and play it through. You will be surprised.

    Then try with diff lock on. Nothing, zero, nada, zilch. Proven! (OK, I don't say drive with diff lock on. Just to show what the diff does on gravel when fighting the drag of the other axle)

    We should also mention that the guy who operates that CAT grader monster usually just covers the core with soft matter and the solidified corrugation underneath gets opened up very quick again. He should always cut the crown off the corrugation without touching base - if you understand what I am trying to say here.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by SAND View Post
    In my humble opinion, it is more a function of incorrect tire pressure and speed, than 2x4 vs 4x4
    I'm driving my car tyres at 1.3 to 1.5 bar....what pressure would you suggest for a 195 R 15 tyre in a lightweight permanent 4*4...?

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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by SAND View Post
    In my humble opinion, it is more a function of incorrect tire pressure and speed, than 2x4 vs 4x4

    Errrrrrmmm…

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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Bit of both.

    Johan is correct in what he is stating on the surface discussed. On softer surface go for 4x4.

    Tire pressure plays a huge role when it comes to the harder surfaces. We had huge issues on a contract on the Mupane Gold Mine outside Francistown. Corrugated roads was causing lots of issues on trucks, brackets and v-stays breaking off due to vibration. Adjusted tire pressure and the corrugation was a thing of the past.

    Then on 4x4 vs. 4x2. I'm guilty. Traveled to Malengane in the past with my 4x2 Diff-lock. Quite east to see. Compare your tracks with a person in 4x4 at the same time and you will see.

    Thanks Johan, I am one of those that used to be ignorant on this topic.


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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    For safety reasons anyway do 4x4 when hitting gravel, any gravel. That should be a rule!!!
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Edit
    Last edited by K2l2h2r1; 2020/04/10 at 10:31 AM.

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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by SAND View Post
    In my humble opinion, it is more a function of incorrect tire pressure and speed, than 2x4 vs 4x4
    Agreed

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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by Nys View Post
    For safety reasons anyway do 4x4 when hitting gravel, any gravel. That should be a rule!!!
    I was waiting for someone else to mention this. So much more control.

    That should be a rule!!! Cannot underline more.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Biggest problem is tyre pressure. I can take anyone to hundreds of private farm roads that are traveled only with 2wd vehicles that have zero corrugations.
    Some being traveled 50 years plus.
    All these farmers run reduce tyre pressures.

    On a Namib trip in 2011 it were clearly evident when doing the large dunes. One guy in the group refused to go lower than 1.5. He made corrugations up ever Dune. I hated driving behind him.

    If you understand gravel travel speed up.
    If you are a novice stay lower than 60km/h and rattle you teeth out
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by Redman View Post

    Tire pressure plays a huge role when it comes to the harder surfaces. We had huge issues on a contract on the Mupane Gold Mine outside Francistown. Corrugated roads was causing lots of issues on trucks, brackets and v-stays breaking off due to vibration. Adjusted tire pressure and the corrugation was a thing of the past.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by Nys View Post
    For safety reasons anyway do 4x4 when hitting gravel, any gravel. That should be a rule!!!
    Quote Originally Posted by JohanMaree View Post
    I was waiting for someone else to mention this. So much more control.

    That should be a rule!!! Cannot underline more.
    Thanks Gents, I can't agree more. I fail to understand the "but I don't need to engage 4x4 for that route" argument. When your vehicle does have 4x4, use it. It's there, paid for. Specially in a part time 4x4 you basically half the torque delivered to each wheel, which can only be beneficial to any loose surface. It reduces the chance of a tyre losing traction, even momentarily. And I have yet to see a major impact on fuel consumption. The little increase in fuel consumption is probably countered by the fact that your rear wheels wear less.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by grips View Post
    Biggest problem is tyre pressure. I can take anyone to hundreds of private farm roads that are traveled only with 2wd vehicles that have zero corrugations.
    Some being traveled 50 years plus.
    All these farmers run reduce tyre pressures.

    On a Namib trip in 2011 it were clearly evident when doing the large dunes. One guy in the group refused to go lower than 1.5. He made corrugations up ever Dune. I hated driving behind him.

    If you understand gravel travel speed up.
    If you are a novice stay lower than 60km/h and rattle you teeth out
    Reducing tyre pressure on gravel or sand is just common sense. But it gets practiced less and less, just like common sense.
    I think that reduced tyre pressure has a very similar effect, the driven wheels got more grip and a larger contact patch and therefore don't skop up corrugation.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    I think there is a big difference between the "waves" being pushed up on soft sand by a 2x4 and the corrugation on hard gravel.

    They feel the same but are formed in different ways.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    Quote Originally Posted by HugoNotte View Post
    Thanks Gents, I can't agree more. I fail to understand the "but I don't need to engage 4x4 for that route" argument. When your vehicle does have 4x4, use it. It's there, paid for. Specially in a part time 4x4 you basically half the torque delivered to each wheel, which can only be beneficial to any loose surface. It reduces the chance of a tyre losing traction, even momentarily. And I have yet to see a major impact on fuel consumption. The little increase in fuel consumption is probably countered by the fact that your rear wheels wear less.
    It is because for some strange reason the manne around a braai rate an oke who can do an off road track only in 2wd as a hero. Again, for some strange reason it shows skill. In the "old days" of beach driving here, driving in 2wd would have earned you either a stern talking to or a klap or two. Or three if your tyres were still at 3bar as it F's up the at times dificult ramps off the beach.

    Another reason is that our cars these days have solenoids acitvating the diffs and these things need to work or they start sticking the day you really need drive tonall the wheels.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    We drive on Gravel every day. Our Farm is off the main Sappi gravel roads. Observations are that it is a smoother ride in 4x4 and there are 2 sweet spot speeds. 35 kms / hour and 70 kms / hour. We are unfortunate that the Sappi timber trucks destroy the roads very quickly even though Sappi grade and resurface 3 times a year. The old corrugations eventually come through. I agree with Johan that the grader should skim the crown before the road is resurfaced. I run my tyres at a lower pressure as well around 1,8 bar. Fortunately the Ford Ranger with OME suspension does give a good ride on most surfaces.
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    Default Re: Guys, PLEASE!!! ALWAYS 4x4 on gravel

    A study regarding corrugation was done in 1962.

    Some science is never a bad thing.

    Keith B. Mather from the University of Melbourne, way back in 1962, who did the experiment that finally gave the real answer. He attached a small wheel to an arm about one metre long, and then drove it around in circles with a variable-speed electric motor. The wheel travelled on a circular concrete track, which he covered with different materials. In fact, to be thorough, not only did he use a fine-sifted sand, but he used different coarse sands, and various dry products like gravel, rice grains, and even split peas and sugar! And he found that provided that these materials did not stick together, and were dry, he could always generate corrugations.
    He found that corrugations came quickly if he had hard tyres, but slowly with soft tyres. The corrugations came readily in dry materials, but very slowly, if at all, in wet sand. It made no difference to the corrugations if the wheel was a driving wheel, or a driven (or rolling or idling) wheel. And he found that the major factor in generating corrugations was the road speed of the vehicle.
    Last edited by Cyclone101; 2020/04/10 at 12:30 PM.

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