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Old 30th September 2008, 12:29   #1
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Default How to tell whether electronic 4x4 is engaging : Easiest way

In city we often do not have any access to trails where significant wheelspin can happen due to slush.
So before heading for a trip to the wild, there is no way to tell whether the electronic 4x4 is working or not.
The 4H or 4L light may come on, but due to some glitch you may be in 2WD mode.
so in the city, whats the easiest way to tell whether 4x4 is engaging.
If course I can take a U turn on tarmac and make out from the dance, but thats bad for the car, so am looking for some easy, non damaging way of doing so.
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Old 30th September 2008, 12:34   #2
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Doesnt 4WD mode impact pickup? As compared to 2wd that is.
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Old 30th September 2008, 12:35   #3
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accelerate rapidly from stop see if you can wheel spin the back. If you can easily do then 2wd if it proceeds without spin then 4wd. But this wont work if you have traction control on your vehicle. just my 2 paise
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Old 30th September 2008, 12:54   #4
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Mall parking lot entry points, the ones with steep straight climbs / descents. Stop midway and switch to 4L here. Remember to reverse in 2H once you reach the top / bottom. This is the easiest way to find out.
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Old 30th September 2008, 13:04   #5
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How to check 4L
With 4L the gear ratio change makes it obvious.
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Old 30th September 2008, 14:02   #6
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Quote:
Originally Posted by tsk1979 View Post
How to check 4L
With 4L the gear ratio change makes it obvious.
I'm sure you meant 4H there. Anyway, no chance of a mud / gravel road, some sand in a construction lot? That would make it easy to check.
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Old 30th September 2008, 14:08   #7
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Yup, I meant 4H, I think I will look for some empty ground.
So when I go there. Do what
Engage 4H, rev engines and and see if I get wheelspin on front wheel?
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Old 30th September 2008, 14:39   #8
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no sir, just drive around in 2H, when you encounter the wheels spinning or the vehicle sliding, shift into 4H and see what happens - do you encounter the same behaviour?
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Old 30th September 2008, 14:48   #9
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Default How to Check the 4wd is engaging

The Basic electronic 4WD system have 2 circuits.
1) Engage the Front Axle - The solenoid actuated selector engages the front propellor shaft
2) Lock the Front Free-Wheeling Hubs - Solenoid actuated selector engage or disengage the front free-wheeling hubs.

If both the circuits are working then while turning the steering will have a kick-back due to the lack of differential action between the front & rear diffs.

The simplest way to check is to engage 4WD and take a half-turn left and a half-turn right.

Another method is to switch from 2H-4H-4L and check is the transfer-case is reducing the drive. This is not fool proof, doesnot indicate the locking of the front-freewheeling hubs.

Regards,

Arka
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Old 30th September 2008, 16:20   #10
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The moment a vehicle switches to 4wd, the pickup power will drop. The vehicle will feel more grippy, controlled and it's sound will change a bit too.

Better, try switching the same yourself sometimes and notice all the differences before you set off for that tour/trip.
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Old 30th September 2008, 17:37   #11
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Default 4WD - pickup or acceleration

Quote:
Originally Posted by speedzak View Post
The moment a vehicle switches to 4wd, the pickup power will drop. The vehicle will feel more grippy, controlled and it's sound will change a bit too.

Better, try switching the same yourself sometimes and notice all the differences before you set off for that tour/trip.
Pickup; if it is acceleration then it will improve in a straight line in 4H (4WD High)

In 4L (4WD-LO) the acceleration will improve considerable but will only be felt for the first few inches

Regards,

Arka
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Old 30th September 2008, 17:58   #12
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Tanveer, haven't you felt any perceptible difference after engaging 4H on "kutcha" road patches? With the amount of mud & slush we have around any construction site anywhere n the NCR, you should be able to feel it pretty clearly.

Apart from this, as Arka has suggested, try a half left or right lock on tarmac - you'll feel the difference immediately. Be careful you don't stall the engine with a violent jerk

Last edited by suman : 30th September 2008 at 18:01.
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Old 30th September 2008, 17:58   #13
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Quote:
Originally Posted by ex670c View Post
The simplest way to check is to engage 4WD and take a half-turn left and a half-turn right.
He said it all. Driving with 4x4 engaged on hard surfaces will cause wear only after prolonged use, there is no harm in taking a couple of turns on tarmac in 4WD.

The front hubs of the Safari (and maybe the Scorpio too) automatically lock through an independent internal mechanism whenever the front axle is driven. The Endy has electric hub locks.
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Old 30th September 2008, 21:25   #14
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Quote:
Originally Posted by Alfa_Kilo View Post
Driving with 4x4 engaged on hard surfaces will cause wear only after prolonged use, there is no harm in taking a couple of turns on tarmac in 4WD.
Be carefull there, Engaging 4wheel drive on a vehicle with a central differential will be no problem. But if you have a part time 4x4, which a majority of 4x4's in India are(and they dont have central differentials), you have be asking for trouble if you engage 4x4 on a hard surface, that is if you dont have good tires.
I mean, in a part time 4x4, the lack of a central differential in a transfer-case does not adjust between the revolutions of the front and rear axles, like the axle differential adjusts revolutions between both sides of the axle. Therefore,when a vehicle turns, every tire is turning in a different axis and therefore a different speed/revolution, and the front axle is actually turning a bit slower than the rear axle, with the inner front wheel traveling in the slowest, and thus having the least revolutions . If there was a central differential it would have adjusted the revolution between the front and rear axle, but since a part time 4wheel drive does not have it, it will depends only on wheel slip in such a case.

So if on a hard surface like a metalled road, with a good grip on the tires, turning a part time 4x4 is a sure recipe for breaking something. Since there is nothing to adjust revolutions between the front and rear axles, the entire system locks up and breaks if more power is applied. Here if you have a free-wheeling hub, it actually works as a pressure fuse, coz a chain is only as strong as its weakest link, and the free-wheeling hubs are weaker than atleast the axles and the gearboxes, so it takes the torque load and breaks.

Anyways, dont underestimate torque, even if it does break the hubs, it would have still caused some damage to the gearbox, the axles, the differential gears, etc. So my advise is, please be careful, its your money at stake.
Regards,
Bikram
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Old 30th September 2008, 23:24   #15
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Quote:
Originally Posted by brutus View Post
Here if you have a free-wheeling hub, it actually works as a pressure fuse, coz a chain is only as strong as its weakest link, and the free-wheeling hubs are weaker than atleast the axles and the gearboxes, so it takes the torque load and breaks.
Wow, didn't know about that benefit of free wheeling hub, thanks.
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