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Old 1st January 2010, 13:51   #1
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Default Stupid Questions on offroading thread

I am hoping off-roading experts here will help clarify some of these seemingly stupid questions from newbies like myself. While I dont do too many OTR trips, i do need to go into forests regularly and mostly alone and dont want to get stranded or worse break anything in the middle of nowhere! it came quite close to that some days back!

so here goes.

1. We are taught early on to never use 4WD on Hard surfaces as it causes wind-up or something? Fair enough. So we dont use it on tarmac roads and highways. But will it cause problems if we use it on dry forest trails?

The trails in question are mild to very steep and curvy trails dug out of the hill sides and covered with gravel and rocks: very typical of the Konkan. In the rainy season ofcourse there is water flowing down many of these trails making 4WD essential. But what about the dry season?

In 2WD mode, i find a lot of slipping: especially on the steeply climbing/descending curves and can hear noises suggesting the rear tyres are taking some deep cuts from the rocks. in 4H mode however the vehicle feels more stable riding over such terrain: climbs "feel" super smooth and i have never once stalled in the middle of a climbing turn: very common when in 2W mode.

2. What to do if we actually stall in the middle of steeply climbing TURN? The gradient is roughly 40 degrees plus atleast.

What i do now is to engage 4L and let the engine do its job. We are told that we should always keep the wheels straight when starting out of a stall in 4L. But what if straight ahead is a sheer drop? What is the best way to get out of a stall in a steeply curvy gradient situation?

More questions coming up!
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Old 1st January 2010, 14:27   #2
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I think what you are doing is fine. 4H for rutted/gravel sloping jungle trails should be ok.

In 2nd case also, if you can move up then fine, else one could also try backing off in reverse and then climbing again. Depending on how steep/condition of trail, one could use 4H/4L accordingly.

Let's see what others have to say here..
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Old 1st January 2010, 14:30   #3
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1. As long as tires can slip, its fine. Since you are seeing slipping, it means transmission windup won;t happen
2. Try to reverse a bit if possible, otherwise, keep steering wheel turned. But make sure you engage handbrake shift to neutral, depress clutch and then engage 4L. After that use the same technique you use for hill starts. Also take care to release clutch very slowly, as due to enourmous torque in 4L, wheelspin can occur.
But on a very sharp turn, where momentum is necessary, try to roll back a bit to a lesser gradient before starting again.
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Old 1st January 2010, 15:22   #4
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1) If you are slipping in 2WD, that is good enough reason to switch to 4WD. As long as terrain is providing slippage, engaging 4WD is fine.

2) If you stall in the middle of a climb. You have couple of options. Start the engine in gear while tapping the acclerator a little, this may not always work. Or you can start the engine in neutral while in brake and then toe-heel into accelerator. That is toe on the brakes and heel on the acclerator, and slowly lift the toe and press the heel.
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Old 1st January 2010, 23:13   #5
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Thanks a lot for the replies.

To continue: It is one thing to slot into 4H or 4L just at the beginning of a climb. this requires me to come to a full stop and then shift from 2H to 4H/L each time: too time consuming. Would it be safe to leave it in 4H as soon as i come to the "rock patch" where the series of climbs interspersed with regular sections begins? I noticed this time that the transfer case is heating up after some time of driving in 4H. Is this normal?
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Old 2nd January 2010, 12:12   #6
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Some heating up is okay, but if its hot to touch, it can be due to old transfer case oil, or wrong grade. Generally, for most cars SAE90 is good(Castrol Transpower is a good brand here).
Then you also have Dana SAE 90 oil.
However if you accidently put 75W140 etc., oils, this can lead to overheating.
So check out the owners manual and see whether its SAE 90 or 75W150 etc., that the transfer case requires.
That said, if you are using 4WD frequently, change transfer case oil atleast once every 25000kms
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Old 3rd January 2010, 14:46   #7
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Quote:
Originally Posted by COUGAR View Post
Thanks a lot for the replies.

To continue: It is one thing to slot into 4H or 4L just at the beginning of a climb. this requires me to come to a full stop and then shift from 2H to 4H/L each time: too time consuming. Would it be safe to leave it in 4H as soon as i come to the "rock patch" where the series of climbs interspersed with regular sections begins?
Hi,
My two bits.

If I thought I MIGHT need 4W/ L, always made the choice BEFORE needing it.
On good surfaces, absolutely not advised. But I see no options. Have done it before. Will continue to do so. Also am sure, have significantly reduced service life of UJs/ yokes etc. Fortunately, have not stripped teeth, or damaged splines etc so far.

You can try reversing from time to time on straight sections to unwind the transmission, but I think its effects will be more psychological than real as the transmission will wind up in no time at all. However your "too time consuming" statement shows a degree of impatience which might get you in trouble

Regards
Sutripta
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Old 4th January 2010, 12:51   #8
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Default Basic S

Quote:
Originally Posted by COUGAR View Post
I am hoping off-roading experts here will help clarify some of these seemingly stupid questions from newbies like myself. While I dont do too many OTR trips, i do need to go into forests regularly and mostly alone and dont want to get stranded or worse break anything in the middle of nowhere! it came quite close to that some days back!

so here goes.

1. We are taught early on to never use 4WD on Hard surfaces as it causes wind-up or something? Fair enough. So we dont use it on tarmac roads and highways. But will it cause problems if we use it on dry forest trails?

The trails in question are mild to very steep and curvy trails dug out of the hill sides and covered with gravel and rocks: very typical of the Konkan. In the rainy season ofcourse there is water flowing down many of these trails making 4WD essential. But what about the dry season?

In 2WD mode, i find a lot of slipping: especially on the steeply climbing/descending curves and can hear noises suggesting the rear tyres are taking some deep cuts from the rocks. in 4H mode however the vehicle feels more stable riding over such terrain: climbs "feel" super smooth and i have never once stalled in the middle of a climbing turn: very common when in 2W mode.

2. What to do if we actually stall in the middle of steeply climbing TURN? The gradient is roughly 40 degrees plus atleast.

What i do now is to engage 4L and let the engine do its job. We are told that we should always keep the wheels straight when starting out of a stall in 4L. But what if straight ahead is a sheer drop? What is the best way to get out of a stall in a steeply curvy gradient situation?

Hi Roy,

I will answer in points

1) If the wheels slip or catch air your can use 4WD.

2) If you have to engage 4WD High, then you can also engage 4WD-Lo and select higher gears from the Gearbox, this prevent clutch wear and you get a wider range of gearing while driving, rather than stopping and changing.

3) If you stall while climbing= REVERSE 4WD Lo
i) Press the brakes
ii) engage reverse & 4WD Low and release the clutch.
iii) Release brakes and let gearing hold the vehicle
iv) crank and gently accelerate. if the vehicle reverses too fast/uncomfortable, tap the brakes, and guide her down.

Regards,

Arka

PS - The attachment is from the CJ3B Page.
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Old 4th January 2010, 13:24   #9
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Another Noob question:
What exactly is a transmission wind-up? What exactly happens, how does reversing help? Any other harmful effects happen if 4WD is engaged on the tarmac?
Any thumb rules to follow when one should / shouldn't engage 4WD?
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Old 4th January 2010, 13:41   #10
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arka

Noob followup question on your attachment.

I had asked this question on scorp 4wd as well - I need to control the downslope speed which is about 75-100 meters long and fairly steep gravel path.


The manual you have attached (assuming part time 4WD system) talks of engaging 4wd lo and first gear and not using brakes. The question then is if this path turns and has a few twists, is there an impact on 4WD system like windup? Or will going down at low speeds reduce chance of such an occurence


Cheers
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Old 4th January 2010, 14:04   #11
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Default Transmission Wind-Up

Hi Guys,

Transmission Windup occurs when, there is no differential action between the Front Differential and Rear Differential.

But if the Centre Differential is OPEN, then the vehicle becomes and All-Wheel Drive .

So All 4WD vehicles Suffer from Transmission Wind Up .

Additional Factors which attribute to wind-Up

1) Steep Drive-Line Angles

2) LSD & Differential Locks

3) Front Axle - Universal Joint Type. The Rzeppa Joints/Benedix -Weiss Type aka Constant velocity types reduce Transmission Wind Up.

Effects of Transmission Windup.

1) Wears out the Drive Line Components.

2) T-Case slips out occasionally.

3) Damages the Front Axle (Steering Axle).

How to minimize Transmission Windup.

1) DO NOT take sharp Turns Off-Road in 4WD Hi/Lo e.g as we turn on the road.

2) DO NOT force the steering while turning, In the UJ Type Front-Axle the steering kickback; tap the accelerator and turn a bit, allow the steering to re-center, and repeat.

FRONT AXLE DAMAGE.
1) NEVER Park the vehicle in 4WD with the steering turned.

2) If the Steering has to be turned and parked i.e slope or gradient to prevent the vehicle from rolling; then start the vehicle and reverse and straighten out the steering, this unloads the universal joints in the Front-Axle and prevent them from breaking.

Regards,

Arka
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Old 4th January 2010, 14:10   #12
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Default Transmission Wind-Up - pt2

Quote:
Originally Posted by adzegeek View Post
arka

Noob followup question on your attachment.

I had asked this question on scorp 4wd as well - I need to control the downslope speed which is about 75-100 meters long and fairly steep gravel path.


The manual you have attached (assuming part time 4WD system) talks of engaging 4wd lo and first gear and not using brakes. The question then is if this path turns and has a few twists, is there an impact on 4WD system like windup? Or will going down at low speeds reduce chance of such an occurence


Cheers
Hi Adzgeek,

The Faster we go in 4WD or the Tighter we turn; the transmission winds up.

Don't force the steering to turn, turn and allow it to re-center and tap the accelerator, while turning.

IIRC the 4WD Scorpio has a Rack & Pinion Steering, so you have to be more careful.

Also if you feel the vehicle is descending faster than you like in 1st 4WD-Lo, then gently tap the brakes in cadence, with your descent.

Regards,

Arka
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