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Old 6th June 2008, 14:05   #76
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Originally Posted by headers View Post
This is a great technique even in 2wd when one gets stuck and both wheels are spinning. Apply brake gently until one of the wheels stop rotating and the vehicle will move forward!
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Or maybe you need the right technique, Tanveer Sir!
Headers, am I missing something?
Your post makes 4WD completely redundant!
The vehicle WILL MOVE FORWARD!!

Can we allow for a bit of circumstances, situation or terrain?
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Old 6th June 2008, 20:31   #77
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Originally Posted by anupmathur View Post
Headers, am I missing something?
Your post makes 4WD completely redundant!
The vehicle WILL MOVE FORWARD!!

Can we allow for a bit of circumstances, situation or terrain?
http://www.team-bhp.com/forum/techni...tml#post454850 (Driving on beach sand)

Hope that clears it..I learnt it from there ..
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Old 6th June 2008, 20:58   #78
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Thanks. That's for a specific kind of terrain - beach sand.
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Old 22nd June 2008, 19:30   #79
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Content here supplied by Courtesy 4WD Encounter - Australia.

4WD explained for no-brainers i like me


Four wheel drive vehicles come in all shapes, sizes and body styles with different types of features and equipment. However, there are several basic functions that all 4WDrives have in common.

Drivetrain

A 4WD can be a constant 4WD, part-time 4WD or both. An example of a constant 4WD is a Range Rover. It is always in 4WD and cannot select 2WD at all. A Nissan Patrol is an example of a part-time 4WD, which means that it can switch between 2WD and 4WD. However 4WD can only be selected when on slippery surfaces. A Mitsubishi Pajero is an example of a 4WD that can be both a constant 4WD and a part-time 4WD. It can select 2WD, constant 4WD and locked 4WD. The difference between the Patrol and the Pajero is that the Pajero has a centre differential. A centre differential allows 4WD to be used on normal roads (constant 4WD) and can be locked for off-road use (part-time 4WD). The "axle/transmission windup" text below explains why a part-time 4WD cannot be driven in 4WD on the bitumen

Axle/Transmission Windup

When a 4WD is travelling in a straight line all four wheels rotate at the same speed, but during cornering each wheel travels at a different speed due to the radius of the turn. All vehicles have a differential on the front and rear axles to allow the wheels on the same axle to rotate at a different speed. Constant 4WDs have a central differential fitted to allow for different speeds between front and back wheels, but most part-time four wheel drives do not.
When a part-time 4WD (without a centre differential) is in 4WD an attempts to corner on bitumen, all wheels need to rotate at different speeds, but without a centre differential they cannot. This creates the phenomena called "axle windup" or "transmission windup". High strain is placed on the drive shafts and transmission, eventually causing one of two things to happen. Either one of the wheels slips or spins to overcome the stress or the drive-shaft/transmission breaks. This is why part time 4WDs should never select 4WD on bitumen.
Constant 4WDs have a central differential within the transmission to overcome this problem. However once in the dirt a constant four wheel drive can be bogged with only one wheel spinning. This is why they have a central differential lock that stops the action of the centre diff and makes it like a part-time four wheel drive in 4WD mode. The centre diff lock should never be used on bitumen or non-slip surfaces for the reasons mentioned above.
In reality, a 4WD is only a two wheel drive with one front and one back wheel driving when traction is lost. One wheel on each axle spins while the other receives no drive at all due to the action of the differential. The exception to this is where a limited slip or locking differential is fitted. A limited slip diff allows a limited amount of drive to be applied to the stationary wheel before the other wheel on the same axle spins. A locking diff allows no slip at all and both wheels on the same axle turn at the same speed, regardless of the amount of traction.

High/Low Range

To enable a 4WD to travel at lower speeds while travelling on rough terrain it needs lower gear ratios. Not all 4WDs have low range gearing and this restricts their ability to tackle rough terrain. However 4WDs that lack low range gearing are generally not built for severe off-road conditions or sometimes have a "crawler" 1st gear to compensate for the lack of low range gearing.
The high range ratios in 4WD mode are the same as the gear ratios in 2WD. When low range 4WD is selected, the gear ratios are approximately half that of high range, although the exact ratio varies for each vehicle manufacturer.
For example this means that if an engine speed of 3000 rpm in high range fourth gear is 100 km/h, then in low range at the same engine speed and the same gear, the speed would be around 50 km/h.

Some points to note about low range gearing are:

You cannot select low range in 2WD mode.
  • You do not have to use low range as soon as you put the vehicle in 4WD, but only if the terrain requires it.
  • On most vehicles you have to be stationary when changing from high to low range, check your owners manual for your particular vehicle.
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Old 22nd June 2008, 20:22   #80
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Post deleted by the Team-BHP Support : Please do NOT SPAM the forum. One-liners that add absolutely no value to the thread are strictly prohibited on Team-BHP.

We advise you to visit our board rules section before proceeding any further.

Last edited by GTO : 23rd June 2008 at 12:20.
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Old 26th June 2008, 18:36   #81
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Default Maintaining an Off roader in city environment

Hi,
I will be getting a 4x4 soon(Safari). In all probablity the 4x4 system will be put to use maybe 4-5 times in a year. Rest of the time she will be running on city roads.
I am worried, that due to lack of use, the system may go bad/jammed etc.,
The dealership guy is hell bent on convincing me to buy a 4x2 due to this reason, and says that ever since he's being working in the dealership(3 years+) he does not recollect a single person buying a 4x4.
Similar stories I heard from Mahindra dealers too, who gave me funny looks when I mentioned 4x4.
Is it really a big problem?
I think there are quite a few 4x4(non jeep) users who go offroad very rarely. So how do you make sure that the system stays in top notch position.
I am thinking that maybe on a straight road I can engage 4x4 for 20-30 meters and then disengage. Do this occasionally.
There is an empty ground near my house and I could practice drifting there when it rains.
So 4x4(softroader) owners, what do you do to make sure your system keeps on running good in the city.
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Old 26th June 2008, 20:52   #82
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tsk1979, you have 2 options:

1. try and find some empty construction lot (which will have sand dumped) or some spot off a highway where you can go once a month and offroad for a short distance. You don't have access to a beach otherwise this would have been easy.

2. In a straight line, you can switch to 4H or even 4L (on some steep inclines / declines) for a short distance. Remember to reverse a few metres in 2H, you can feel the steering heaviness (present when you engage 4H or 4L) disappear after some reversing.
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Old 26th June 2008, 21:02   #83
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I am worried, that due to lack of use, the system may go bad/jammed etc.
Is this for real? Does it help if the 4x4 is engaged on roads being constructed and full of pot-holes and stones?
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Old 26th June 2008, 21:13   #84
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Check your manual. Some types of 4x4 should be engaged on loose surfaces and not on hard pavement.

You dont need 4x4 to go thru potholes.
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Old 26th June 2008, 21:20   #85
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Quote:
Originally Posted by tsk1979 View Post
Hi,
I will be getting a 4x4 soon(Safari). In all probablity the 4x4 system will be put to use maybe 4-5 times in a year. Rest of the time she will be running on city roads.
I am worried, that due to lack of use, the system may go bad/jammed etc.,
The dealership guy is hell bent on convincing me to buy a 4x2 due to this reason, and says that ever since he's being working in the dealership(3 years+) he does not recollect a single person buying a 4x4.
Similar stories I heard from Mahindra dealers too, who gave me funny looks when I mentioned 4x4.
Is it really a big problem?

The sales people at the dealership do not have a clue about 4wd- its use & disuse. Neither have they driven one. He does not recollect a single person buying a 4wd because most people buying a suv in India do not use it as it is intended, therefore there is practically no 4wd application. 90% of the suv's are used on tarmac in city & highways where 4wd is not required.
Therfore selling a 2wd is easy since most buyers dont need 4wd. So when a buyer like you and me come along and demand 4wd there is a strange look on their face. Cant blame them.


I think there are quite a few 4x4(non jeep) users who go offroad very rarely. So how do you make sure that the system stays in top notch position.
Firstly nothing goes wrong with it. And ur going to use it 4-5 times a year so do not worry.

I am thinking that maybe on a straight road I can engage 4x4 for 20-30 meters and then disengage. Do this occasionally.
There is an empty ground near my house and I could practice drifting there when it rains.
Good if you want to try your skills , but does not make any difference to the 4wd setup if you dont engage 4wd.
So 4x4(softroader) owners, what do you do to make sure your system keeps on running good in the city.
The reason why you are buying a 4wd like you mentioned earlier is that you dont want to get stuck in a situation with a buffalo on 2 wheels. So thats that. MOst people do not encounter nor visualise the buffalo situation because they "play safe".
If you want to "play safe", then buy 2wd.
And please, please, do not ask or listen to sales talk. They are just trying to fill the order book as per their requirements, not yours!

I feel as of today that i can comfortable use 4wd on the highway in bombay. The mastic asphalt is so , so , so slippery that 4wd high does a good job on it. tried it twice already, super duper. And im dead sure im not killing my differentials.
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Old 26th June 2008, 21:25   #86
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Tanveer, I think we should ask Suman and Steer to post their thoughts about the usage or non-usage of 4x4 in the city. Suman, if I am correct, has not been out of town in the Safari for a long time and thus will be in a better position to clear this doubt.
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Old 26th June 2008, 21:27   #87
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Originally Posted by BUSA View Post
Real time AWD are mostly in 2WD mode and shift to AWD when there is loss of traction or when the mechanism senses the requirement.
there are quite a few vehicles like the audis (Q7, A6, A8 & new A4) which has full time AWD. so what in their case?
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Old 26th June 2008, 21:30   #88
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there are quite a few vehicles like the audis (Q7, A6, A8 & new A4) which has full time AWD. so what in their case?
If I am not mistaken, even the Grand Vitara has a full time AWD. Samurai and Sudev can confirm this.
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Old 26th June 2008, 21:34   #89
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Originally Posted by SumitB View Post
If I am not mistaken, even the Grand Vitara has a full time AWD. Samurai and Sudev can confirm this.
Yes, but AWD or fulltime 4WD vehicles like GV have limited slip central diff. So it is a non-issue. Meanwhile, I do exercise the 4WD on the CJ340 regularly in my office.

Last edited by Samurai : 26th June 2008 at 21:42.
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Old 27th June 2008, 00:01   #90
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When I had the gypsy I used to cross road dividers using 4WD.
But then I was in college. Guess I will practice in the empty ground.
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