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Old 19th July 2010, 16:13   #91
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Hopping is okay in a gypsy. in a 2.5 ton SUV, hopping is very difficult(due to soft suspension), and risk of damage is high.
right now I use this technique.
Go in 1st low, rpm around 2500, as the front wheels are about to come to the road, I slowly go left and as one front wheel reaches the road I give more steering input.
It is good where traction is good, but when there is less traction, I have to do the same at more speed.
At low speeds, I can easily time the steering turn to the front wheels hitting the road, but at higher speed its not easy.
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Old 19th July 2010, 16:20   #92
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Default Hop, Skip or Jump

Quote:
Originally Posted by robinson.s View Post
Arka,

I think the success rate is comparatively less by taping the accelerator when your front wheels cross the climb.
As your front wheel losses complete traction in such inclines, and unless the vehicle has front dif locks, or the surface of the track has enough grip to give traction in all four wheels, will end up spinning wheels and burning the clutch.
To avoid spin on the edge of the incline or take the risk of hitting the cross member or skid plate, one should take it with the momentum and hop over the edge.

Can you give more insight on this. Really keen to know more, as its one of the most challenging obstacle in a trail.

Regards
Hi Robinson,

From my experience, I have seen, that if you give additional throttle input, just before the front wheels cross the edge the vehicle jumps very violent and the landing is quite stressful.

On the Other hand if you give additional throttle input, just after the front wheels cross the edge, the vehicle hops/flicks over the edge.

It is obviously understood that the vehicle will be under regular/normal/procedural throttle input through out the process of exiting the climb.

What you describe hold good in a situation where a vehicle is stopped or relatively slow.

Why should the Front Wheels loose traction just after is has cleared the edge, the Vehicle will loose 50% of the traction if the front wheels catch air i.e Jump, then even Diff-Locks wont matter neither will the terrain or what tyre we are using.

In Short, keep all the wheels on the ground for as long as possible or give the wheels minimum airtime

Regards,

Arka
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Old 19th July 2010, 16:29   #93
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Quote:
Originally Posted by tsk1979 View Post
Hopping is okay in a gypsy. in a 2.5 ton SUV, hopping is very difficult(due to soft suspension), and risk of damage is high.
right now I use this technique.
Go in 1st low, rpm around 2500, as the front wheels are about to come to the road, I slowly go left and as one front wheel reaches the road I give more steering input.
It is good where traction is good, but when there is less traction, I have to do the same at more speed.
At low speeds, I can easily time the steering turn to the front wheels hitting the road, but at higher speed its not easy.
TSK,

I mentioned hopping, for something more dramatic, I would have said jump.

On a steep slope you will risk the chance of ruining your running boards.

And again considering the WB in question and IFS, at higher Speed up the climb, the chances of lifting a wheel and landing on it increase.

Regards,

Arka
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Old 19th July 2010, 16:33   #94
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Originally Posted by Baburajs View Post
This thread can be a treasure trove is people contribute to it well. I wanted to know this and I know there will be many noobs who wants to know this.

What is the tyre pressures for various kinds of terrain. I know it can vary from vehicle to vehicle and driver to driver. But want to know a generic recommendation. This will help us noobs to atleast know if we need to deflate or inflate.

babu
Hi Babu...

Considering that you already have factored the specificity/subjectivity of using different tire pressures in different circumstances (and terrains) may be you can use the below info as added deliberations;

Sand, mud+slush and rocks combined: ~15psi for non radial tires with taller side walls and 10+ ply rating and ~20psi for radials or off road use purpose brands.

Predominantly Sand: 13-16psi for any tire.

Predominantly Mud+slush: ~17psi for non radial tires with taller side walls and ~22psi for radials or off road use purpose brands.

Predominantly Rocks: ~13psi for non radial tires with taller side walls/10+ ply rating and ~18psi for radials or off road use purpose brands.

Note:
1. The above are cold tire pressures. Continuous running can increase the tire temperatures pushing the tire pressure automatically to a couple of more pounds [per square inch] (psi). Variance in excess if 2psi will require re-adjusting.
2. The above estimates are only ballpark numbers, rely on your personal experience with your tires to use the optimum tire pressure.
3. The above estimates should NOT be used for weak or damaged tires.
4. "~" equates to variance up to 1.5psi.
5. Tire deflation results in loss of ground clearance (GC), if a particular terrain required higher GC, use your discretion wisely on whether you want to preserve one for another as an off-set.
6. Always best to hear from others what has worked for them if they are using your model tire, have a keen ear to something that didnt work...ex, "I tore my side wall" or "my tires kept spinning in that rock surface" or "my tire came off the wheels" etc

Last edited by The Wolf : 19th July 2010 at 16:50.
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Old 19th July 2010, 16:41   #95
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Quote:
Originally Posted by ex670c View Post
Hi Robinson,

From my experience, I have seen, that if you give additional throttle input, just before the front wheels cross the edge the vehicle jumps very violent and the landing is quite stressful.

On the Other hand if you give additional throttle input, just after the front wheels cross the edge, the vehicle hops/flicks over the edge.

It is obviously understood that the vehicle will be under regular/normal/procedural throttle input through out the process of exiting the climb.

What you describe hold good in a situation where a vehicle is stopped or relatively slow.

Why should the Front Wheels loose traction just after is has cleared the edge, the Vehicle will loose 50% of the traction if the front wheels catch air i.e Jump, then even Diff-Locks wont matter neither will the terrain or what tyre we are using.

In Short, keep all the wheels on the ground for as long as possible or give the wheels minimum airtime

Regards,

Arka
Arka,

Absolutely, I agree to that point, additional throttle input before the edge, will make the front wheel jump which is risky.
I want to know, you give the throttle input on 1L or 2L once you cross the front wheel on the edge?

Regards
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Old 19th July 2010, 16:54   #96
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Quote:
Originally Posted by robinson.s View Post
Arka,

Absolutely, I agree to that point, additional throttle input before the edge, will make the front wheel jump which is risky.
I want to know, you give the throttle input on 1L or 2L once you cross the front wheel on the edge?

Regards
Hi Robinson,

Sometimes the vehicle crosses the edge, only just. Then if more than half the vehicle has crossed, I switch from 3rd Lo to 1st Low and tap-release-tap the accelerator to spin the wheels and walk the vehicle across, the edge.

I prefer and suggest the Lowest Gear Possible to prevent the propeller shafts and universal joints from getting stressed, in a lower gear(2nd-Lo/3rd Lo) in the above situation the vehicles sometimes starts to hunt or shudder, because the resistance (Slope/Surface) and weight (Slope/Surface combined with Vehicle Weight) is too large for the gearing, hence the lowest gear ensures maximum torque, and by tap-release-tap the throttle I ensure, that the wheels don't dig in, and turn the steering Left-to-right, to get the side wall to bit and the treads to clear out.

If in the above situation if this does not work then its Reverse-Lo and start all over.

Regards,

Arka
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Old 19th July 2010, 17:45   #97
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Quote:
Originally Posted by ex670c View Post
Hi Robinson,

Sometimes the vehicle crosses the edge, only just. Then if more than half the vehicle has crossed, I switch from 3rd Lo to 1st Low and tap-release-tap the accelerator to spin the wheels and walk the vehicle across, the edge.

I prefer and suggest the Lowest Gear Possible to prevent the propeller shafts and universal joints from getting stressed, in a lower gear(2nd-Lo/3rd Lo) in the above situation the vehicles sometimes starts to hunt or shudder, because the resistance (Slope/Surface) and weight (Slope/Surface combined with Vehicle Weight) is too large for the gearing, hence the lowest gear ensures maximum torque, and by tap-release-tap the throttle I ensure, that the wheels don't dig in, and turn the steering Left-to-right, to get the side wall to bit and the treads to clear out.

If in the above situation if this does not work then its Reverse-Lo and start all over.

Regards,

Arka
Hi Arka,

Thanks for the input; it looks really unique for me, as I have never tried this combination.
But, when you shift from 3Low to 1Low, dont you lose your momentum completely?

And I would like to know, is this same technique used in sandy terrain?


This is the same incline which I tried, and the combination was, with the short run up 1st Low, give the throttle input and get the pace and just few feet before the edge, shift to 2nd Low and give throttle, Once the wheels cross the edge, then tap-release-tap and clear the obstacle in the same gear.
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Off Road Driving Techniques-examm-1.jpg  

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Old 19th July 2010, 18:03   #98
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Quote:
Originally Posted by robinson.s View Post
Hi Arka,

Thanks for the input; it looks really unique for me, as I have never tried this combination.
But, when you shift from 3Low to 1Low, dont you lose your momentum completely?

And I would like to know, is this same technique used in sandy terrain?


This is the same incline which I tried, and the combination was, with the short run up 1st Low, give the throttle input and get the pace and just few feet before the edge, shift to 2nd Low and give throttle, Once the wheels cross the edge, then tap-release-tap and clear the obstacle in the same gear.
Hi Robinson,

In my Previous Post "Sometimes the vehicle crosses the edge, only just. Then if more than half the vehicle has crossed, I switch from 3rd Lo to 1st Low and tap-release-tap the accelerator to spin the wheels and walk the vehicle across, the edge."

I should have added after the vehicle stops on the edge of the climb, and more than half the vehicle has crossed the edge.

The Above incline in EXAMM I did it in 3rd-Lo, and the same climb from 6-10ft from the edge in the UBS's Willys MB was in 1st Lo.

I not yet tried out your interpretation of the above technique in sandy terrain.

Regards,

Arka

Last edited by ex670c : 19th July 2010 at 18:16.
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Old 19th July 2010, 19:20   #99
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Quote:
Originally Posted by robinson.s View Post
But, when you shift from 3Low to 1Low, dont you lose your momentum completely?
The vehicle comes to a complete stop in this situation AFAIK.

Quote:
Originally Posted by robinson.s View Post
This is the same incline which I tried, and the combination was, with the short run up 1st Low, give the throttle input and get the pace and just few feet before the edge, shift to 2nd Low and give throttle,
When you shift gears, you've lost considerable momentum and in certain terrain, the vehicle stops!!
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Old 19th July 2010, 21:05   #100
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Originally Posted by ex670c View Post
I switch from 3rd Lo to 1st Low and tap-release-tap the accelerator to spin the wheels and walk the vehicle across, the edge."
Dear Arka,
This is Thar at Hyderabad prior to AKC, Deepak took it up effortlessly without the tap-release-tap technique... I think. The weight of the vehicle provided enough traction and the power of the engine very easily took it up in one go.

My questions are,
1 Would not momentum be broken in the tap-release-tap technique?
2 Is 1Lo not a better ratio option for such an incline?
3 Engines with less compression/ power, would make it to the top with what technique?
4As the weight would at this angle be about 80% on the rear wheels, how would the front wheels bite the ground in the tap-release-tap technique?
5 How important is momentum? (as I have read that you took UBS Sir's, 3B up, from dead halt very close to the incline).

Also please enlighten what are the best options (gears) from the red-yellow-blue area of travel.

Thanks,
Off Road Driving Techniques-img_6613.jpg
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Old 19th July 2010, 22:26   #101
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Originally Posted by fazalaliadil View Post
Dear Arka,
This is Thar at Hyderabad prior to AKC, Deepak took it up effortlessly without the tap-release-tap technique... I think. The weight of the vehicle provided enough traction and the power of the engine very easily took it up in one go.
The length and degree of incline will decide, along with the power, wheel base and weight of the vehicle, ie the technique. In a CJ3B tap and crawl helps alot/in most of the situations, until its very extreme climb without traction. At that point of time i have moved away from crawl/tapping technique to lil more momentum and a slightly more aggressive throttle input to clear the obstacle.

In day 3 Examm there was this pit where we shared the second technique to DKG, who was not very comfortable and wanted to use tap and crawl. But eventually the momentum technique did the trick.

In short i agree with many it depends on the vehicle and terrain to decide on the technique and most often there are many methods.

Babu reg air pressure, on your vehicles (CJ) tyre's (radials)- for hard muck and rock, go with 20-25 and for really soft slush and sand try 18 psi. Should work fine. If it was NDMS definitely 5 psi pounds less can be experimented. In a typical trail with a mix terrain i would keep it safe at around 20-22 as a compromise which will work in most situations.

ps: I still am more comfortable with AT/MT radials over NDMS. NDMS are very VFM tires, but tyre technology has advanced and i think we should accept it and move on.

Just my observations.
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Old 19th July 2010, 22:35   #102
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Its all jeeps again. As you can see, a SWB can do it. I am trying to understand how to do it without touching undercarriage.
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Old 20th July 2010, 00:11   #103
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Tanveer i atleast don't think in a long wheel base vehicle like safari (even RR and Patrols for that matter) avoiding the under carriage is an option. Good part of the story the safari under carriage can take fair amount of abuse, all you need is some neat skid plates for additional buffer.

EDIT: Even with SWB we scrape alot when we go on OTR's. Then again these vehicles are designed keeping this in mind.

To clear with minimal damage, decent momentum and lift off so that the majority of chassis clears. But then suspension takes the toll. Attempting one wheel at a time beyond a certain angle is absolute NO NO in my books. I rather prefer some scars on the underbody.

Last edited by Jaggu : 20th July 2010 at 00:15.
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Old 20th July 2010, 10:30   #104
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Originally Posted by fazalaliadil View Post
Dear Arka,
This is Thar at Hyderabad prior to AKC, Deepak took it up effortlessly without the tap-release-tap technique... I think. The weight of the vehicle provided enough traction and the power of the engine very easily took it up in one go.

My questions are,
1 Would not momentum be broken in the tap-release-tap technique?
2 Is 1Lo not a better ratio option for such an incline?
3 Engines with less compression/ power, would make it to the top with what technique?
4As the weight would at this angle be about 80% on the rear wheels, how would the front wheels bite the ground in the tap-release-tap technique?
5 How important is momentum? (as I have read that you took UBS Sir's, 3B up, from dead halt very close to the incline).

Also please enlighten what are the best options (gears) from the red-yellow-blue area of travel.

Thanks,
Attachment 390254
Hi Fazal,

I will answer your question by points.

1) The Tap-Release-Tap(Repeat) method or Throttle Modulation is the best method to keep a very high flywheel speed hence momentum of the Flywheel is higher, the variation in throttle input prevent the wheels from digging in, and the change in wheel rpm, has a centrifuge effect to clear out the mud.

2)Gearing has 2 Functions
i) Slow the vehicle Down = Better Control
ii) Increase the Torque at the Wheels.

If I want better control i.e slower speed, I will do the above incline in 1Lo.

3) Power is nothing, Technique is Everything.

4) The 20% Weight on the front wheels have to be judiciously used to gain traction, that is why tap-release-tap (Repeat Can go on for few seconds)

5) I took UBS's Willy's MB, from an dead halt on the Incline all the way out of the climb, by Tap-Release-Tap(Repeat) in 1Lo. This technique rapidly build up Flywheel momentum, which is transferred to the wheel.

6) I don't prefer changing gears in an obstacle while the vehicle is moving. I would have done this in 2Lo, to be safe and comfortable, for a faster pitch 3Lo.

The Tap-Release-Tap(Repeat) can be done mildly or wildly, its like pumping the throttle than flooring the pedal.

Regards,

Arka

Last edited by ex670c : 20th July 2010 at 10:34.
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Old 20th July 2010, 10:35   #105
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Hi Robinson,

In my Previous Post "Sometimes the vehicle crosses the edge, only just. Then if more than half the vehicle has crossed, I switch from 3rd Lo to 1st Low and tap-release-tap the accelerator to spin the wheels and walk the vehicle across, the edge."

I should have added after the vehicle stops on the edge of the climb, and more than half the vehicle has crossed the edge.

The Above incline in EXAMM I did it in 3rd-Lo, and the same climb from 6-10ft from the edge in the UBS's Willys MB was in 1st Lo.

I not yet tried out your interpretation of the above technique in sandy terrain.

Regards,

Arka
Hi Arka,

Would like to know, on 3rd low did you take it in high RPM or just tap-release-tap. And am sure if you take it with aggressive throttle input, the front wheels will just fly.
Does the vehicle generate enough torque to take such incline by just tapping the accelerator?
Perhaps your axel ratio would have made the difference?

Man, thanks for these techniques. Got enough to experiment these combinations and see how it works with my machines.

Regards
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