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Old 26th March 2012, 23:20   #196
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Default Re: Off Road Driving Techniques

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Originally Posted by kshivaa View Post
can someone please comment on what would have been the right way to tackle this position?

I am planning to re-visit the same place in April 21/28, and would try out whatever is recommended.

thanks
Siva
Are you running Bridgestone H/T?
if you keep doing such terrains in these tires, you will loose the tires.
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Old 27th March 2012, 13:54   #197
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Default Re: Off Road Driving Techniques

Thanks tsk1979, ignored the tire specification. Going through all the threads on off-roading tires. Thinking between Geolander AT and MRF Wanderer. Anyone has suggestions / positive-negative feedback about these two ?
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Old 27th March 2012, 14:07   #198
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Arrow Re: Off Road Driving Techniques

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Originally Posted by kshivaa View Post
...I believe that it is something with the technique, due to which the vehicle did not climb over that rock & the wheels spun.

can someone please comment on what would have been the right way to tackle this position?
...
It is generally difficult to judge the terrain from pics, hence I wouldn't want to give suggestions based on the pics you have posted.

BUT, please do remember that the Thar has a lot of power/torque on tap. The key is to use that power/torque effectively (and the key word in the previous statement is 'tap'). I think you should be able to clear that rock without making the front wheels spin, if you give correct throttle inputs at the appropriate times (without having to use 4L).

Last edited by Blue Thunder : 27th March 2012 at 14:13.
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Old 27th March 2012, 14:52   #199
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Default Re: Off Road Driving Techniques

If you were running 17-20 Psi tyre pressure, nothing would have stopped you on rocks...
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Old 27th March 2012, 14:55   #200
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Default Re: Off Road Driving Techniques

To me, going by that pic, it is simple.

The rock in front of the rear tyre was acting as a "chock" which effectively blocked the wheel and prevented it from climbing over it.

Consider that the rock seems quite large and it is so close to the wheel that there is no chance of any momentum being built up either in order to climb over it (forget for a moment what the tyres would be going through!!).

Hence, even by shoving the Jeep in 4L and trying to accelerate, you couldnt climb over that rock owing to the relatively loose surface and less traction being available for the front wheels themselves. Added to that, you appear to have turned the front wheels, thereby causing them to dig in a bit deeper.

What is worth remembering is that atleast one if not two of the wheels of your 4WD vehicle need to have some amount of traction, in order to get out of a sticky situation or to go over an obstacle such as the one indicated. Just because it is a 4WD doesnt mean that it can automatically leap over such large rocks like a mountain goat can.

Even in a 4WD, one can get stuck nicely in deep slush as I have experienced in the past. If one accelerates one will simply end up digging one's self in deeper. The same goes for loose gravel, loose rocky surfaces etc. Yes the 4WD has a distinct advantage over a 2WD in situations of this nature, but lets remember that 4WD alone is by no means a "cure-all" panacea!



Quote:
Originally Posted by kshivaa View Post
Hi,

I tried to attempt a mini OTR kind of driving over small stones on the empty stream-bed near Puthur. While I switched over to 4WD H, 1 Gear and started the drive

Attachment 907656

in the middle, got struck at one point, with a big rock below my left rear tyre - see photo below:

Attachment 907653

I tried to switch to 4WD Low, 1st Gear and tried to accelerate. This only resulted in the front wheels spinning and getting into the gravel:

Attachment 907654


Finally, I reversed the vehicle, and then went further straight ahead of the rock that was getting below the left tyre and then moved out.

I believe that it is something with the technique, due to which the vehicle did not climb over that rock & the wheels spun.

can someone please comment on what would have been the right way to tackle this position?

I am planning to re-visit the same place in April 21/28, and would try out whatever is recommended.

thanks
Siva
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Old 27th March 2012, 15:00   #201
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Default Re: Off Road Driving Techniques

I need some tips on travercing thick ice with no snow chains.
I have seen, that the rear tends to slide. Most himalyan roads are banked towards the valley side, and this gets even more banked when snow piles on these roads.
So when proceeding forward, the rear of the vehicle slides towards the cliff.

I do not have snow chains. Any tips on minimizing the slip? On softer ice where ice breaks, its not a big problem as wheels dig in, but hard old ice is a big problem.
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Old 27th March 2012, 16:01   #202
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Post Re: Off Road Driving Techniques

Quote:
Originally Posted by kshivaa View Post

I tried to attempt a mini OTR kind of driving over small stones on the empty stream-bed near Puthur.
What about recovery if something goes wrong?

Quote:
I tried to switch to 4WD Low, 1st Gear and tried to accelerate. This only resulted in the front wheels spinning and getting into the gravel:
When your front wheels are digging in without much help, try to 'swerve' the front wheels towards left and right, this will help gaining some 'bite'.

Quote:
Originally Posted by Blue Thunder View Post
It is generally difficult to judge the terrain from pics, hence I wouldn't want to give suggestions based on the pics you have posted.
Quite true, by looking at the pics, it even makes me feel whether the smaller gear lever must be deployed?

Spike
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Old 27th March 2012, 16:35   #203
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Default Re: Off Road Driving Techniques

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Originally Posted by tsk1979 View Post
I do not have snow chains. Any tips on minimizing the slip? On softer ice where ice breaks, its not a big problem as wheels dig in, but hard old ice is a big problem.
Few things that comes to my mind. Just an attempt.

-- Rock the steering so that it creates a decent wide track for rear wheels to follow. As much as possible keep to the side away from valley. Reversing and going forward also helps to level very high snow

-- Try counter steer and keep a slow but steady momentum with a close watch on how close the rear is towards the edge. Do not attempt tricky area with speed, its better to get stuck than to slip off and fall. Dig that snow out (front of the rear tyres esp) in the direction you want the rear wheel to go, if its in a nasty situation

-- Running a slightly lower pressure would also help.

-- Modulate A pedal when the rear starts to slip so that it catches some grip. Even in really precarious situation, if the vehicle is not tilted, a very gentle throttle with counter steer would help you. Of course use 4 wheel drive with 2 low (experts please comment).

But best thing to do would be to get that nasty snow chain installed.
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Old 27th March 2012, 17:07   #204
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Default Re: Off Road Driving Techniques

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Originally Posted by SPIKE ARRESTOR View Post
...it even makes me feel whether the smaller gear lever must be deployed?...
...if only to reduce the overload on just the rear axle.
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Old 27th March 2012, 17:21   #205
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Default Re: Off Road Driving Techniques

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Originally Posted by kshivaa View Post
I believe that it is something with the technique, due to which the vehicle did not climb over that rock & the wheels spun.
The terrain appears deceiving in photographs to me. Maybe you should NOT engage 4wd and try to just crawl without A, B and C in 1st or 2nd Gear. The THAR CRDe will do it
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Old 27th March 2012, 18:53   #206
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Default Re: Off Road Driving Techniques

Folks, a question:

Some dirt tracks are pretty rocky in stretches, and also steep. I often come across these tracks in the Nilgiris in the forests and hills. Example of such a trail is here: http://www.team-bhp.com/forum/attach...s-dsc_0327.jpg . This trail - though it seems somewhat flat in the picture - has a number of steep and sharp hairpin bends with largish rocks positioned right near the bends.

Climbing up in a Fortuner is no issue in normal 4H, but while climbing down e.g. a steep rocky hairpin bend, I am often in a dilemma: whether to engage low range or not.

When I use low range, going down is effortless without touching ABC due to the slow speed. If I don't use low range, I have to use brakes + clutch to slow the speed. Note: when I do use low range, I sometimes have to reverse for a few feet to make the differential locked icon go away.

Now, I am not fully sure whether these rocky surfaces have too much traction for transmission wind up in 4L. I need to have my speed slower than downhill 1st gear 4H crawl speed (speed attained without using ABC) to tackle some stretches.

The trade-off is between possible transmission windup and potential overuse of clutch.
In rainy season or when there is mud coating on such rocky trails, I can use 4L without worry due to the slipperiness. But what about dry season? My research tells me that it is not a very good idea to use locked centre differential in a turn on high traction surfaces. But if I don't, I will need to (ab)use the clutch more to regulate my speed.

Any recommendations? From my personal comfort feel and from what I have read on the net and in 4WD books, using 4L seems to be a better option. What do people do when crawling down high traction rocks or rocky surfaces? How do they avoid windup?

Last edited by nilanjanray : 27th March 2012 at 18:58.
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Old 27th March 2012, 19:00   #207
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Default Re: Off Road Driving Techniques

Use 4L but keep the speeds slow by using B pedal, that should help avoid wind ups. Its the speed that buggers up the tranny, if you do it slow, should not be a big issue to the tranny.

I sometimes shift to 4L on tarmac and crawl at idle, just to get the oil churning and gears moving in 4x4 crawl = very less than 5 kmph.
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Old 27th March 2012, 21:32   #208
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Default Re: Off Road Driving Techniques

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I sometimes shift to 4L on tarmac and crawl at idle, just to get the oil churning and gears moving in 4x4 crawl = very less than 5 kmph.
You can also achieve the same while waiting at the street signals. Slot the transfer case into neutral, engage 1st gear and lift you foot off the clutch. Repeat in the exact opposite order before take off.
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Old 27th March 2012, 22:07   #209
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Default Re: Off Road Driving Techniques

Quote:
Originally Posted by Jaggu View Post
Use 4L but keep the speeds slow by using B pedal, that should help avoid wind ups. Its the speed that buggers up the tranny, if you do it slow, should not be a big issue to the tranny.

I sometimes shift to 4L on tarmac and crawl at idle, just to get the oil churning and gears moving in 4x4 crawl = very less than 5 kmph.
In 1st gear 4L, the Fortuner goes very slowly - if I remember correctly, the transfer case ratio is 2.57. Don't need to use brakes that much, if at all. But for future (challenging) trails that I might come across some day, will practice left foot braking
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Old 27th March 2012, 23:25   #210
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Default Re: Off Road Driving Techniques

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Originally Posted by nilanjanray View Post
In 1st gear 4L, the Fortuner goes very slowly - if I remember correctly, the transfer case ratio is 2.57. Don't need to use brakes that much, if at all. But for future (challenging) trails that I might come across some day, will practice left foot braking
No need for left foot braking, just a tap with right foot will bring things in control. Depending on the ratio and engine RPM you can play with the A or B pedal to keep the vehicle rolling, but also to keep the RPM under control. Since its fortuner you have an RPM meter also to keep tab.
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