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Old 1st December 2013, 18:30   #241
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by Sheel View Post
I am going to read this thread as part of my home work. BTW, what does MLD mean? How it helps ?
Manual Locking Differential. Left and right wheels of same axle (in this case the rear axle) turn at the same rate - so even if one wheel loses traction, it will not spin out all the torque to that axle. If the other wheel has enough grip to pull out the car, it will.

If both wheels of the same axle lose traction, you're stuck in a 2wd vehicle, without 4wd to engage the other axle.
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Old 1st December 2013, 18:36   #242
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Default Re: Driving all four wheels: how is it done?

Does this feature, feature as OE in a Scorpio 4Wd?
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Old 1st December 2013, 18:42   #243
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Default Re: Driving all four wheels: how is it done?

Not OE in the Scorpio for Indian markets, but it's a direct fit without modifying the differential. Around 35k is the cost IIRC - ask 1100D or devdath.
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Old 1st December 2013, 19:16   #244
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Default Re: Driving all four wheels: how is it done?

Isn't MLD = Mechanical locking differential ?
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Old 1st December 2013, 19:44   #245
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Default Re: Driving all four wheels: how is it done?

You know guys, I am on page 8 and I didn't understand much.

In short, can 4H or 4L be engaged in a moving car having part time 4WD? Or to shift to to 4L, you have to stop, shift to neutral and then engage?

How will MLD be of help in a Scorpio?

Any precautions to be taken while servicing a part time 4WD apart from changing differential oil?

Thanks

^More questions as I get wiser
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Old 2nd December 2013, 08:06   #246
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by Sheel View Post
In short, can 4H or 4L be engaged in a moving car having part time 4WD? Or to shift to to 4L, you have to stop, shift to neutral and then engage?
4H can usually be engaged at speeds lower than ~40kmph. However, for engaging 4L, you need to stop, shift the 4WD gear box (Transfer Case) to neutral and then shift to 4L. The main gearbox doesnt need to be in Neutral.
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How will MLD be of help in a Scorpio?
MLD is definitely a nice add-on to have, however, considering the road scenario, a 4WD is MORE than the enough for most of the purposes. Diff-Locks are for extreme offroading. However, if you are serious about off-roading, then having diff-locks help you go slow, thereby saving clutch, suspension and fuel.
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Any precautions to be taken while servicing a part time 4WD apart from changing differential oil?
You just get a transfer case, a front differential and a propshafts more. So, nothing much. Just make sure all the joints are proper and FWH's working etc..
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Old 2nd December 2013, 10:50   #247
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by Samurai View Post
Isn't MLD = Mechanical locking differential ?
Can mean either. With respect to the Scorpio, it's 'mechanical', but w.r.t. to the Gurkha it's 'manual'. I stand corrected!
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Old 2nd December 2013, 21:32   #248
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Default Re: Driving all four wheels: how is it done?

^^^
1100Ds Eaton unit is an autolocker. Which certainly locks mechanically. Automatically, not manually.

In my vocabulary, autolockers are not MLDs.

Regards
Sutripta
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Old 4th December 2013, 08:44   #249
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Default Re: Driving all four wheels: how is it done?

Quote:
Originally Posted by dhanushs View Post
4H can usually be engaged at speeds lower than ~40kmph. However, for engaging 4L, you need to stop, shift the 4WD gear box (Transfer Case) to neutral and then shift to 4L. The main gearbox doesnt need to be in Neutral.
From what I see, there is just one gear lever in the Scorpio or Storme. And a rotary switch for 2H, 4H and 4L.

(There is one additional lever in the SFX, but its gone, for good & I am not bothered now.)

Quote:
MLD is definitely a nice add-on to have, however, considering the road scenario, a 4WD is MORE than the enough for most of the purposes. Diff-Locks are for extreme offroading. However, if you are serious about off-roading, then having diff-locks help you go slow, thereby saving clutch, suspension and fuel.
I don't plan any OTR's. Just normal off road scenarios one comes across while commuting.

Quote:
You just get a transfer case, a front differential and a propshafts more. So, nothing much. Just make sure all the joints are proper and FWH's working etc..
Hmmm. Thanks on this. I will make a note of it & read the service manual as well.

SS-T & others - From 4L mode, to go back to 4H or 2H, I need to reverse a bit, after moving the lever to the desired position (4H, 2H & the light on the console goes off?)

Thanks everyone
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Old 4th December 2013, 15:19   #250
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Default Re: Driving all four wheels: how is it done?

Quote:
Originally Posted by Sheel View Post
From what I see, there is just one gear lever in the Scorpio or Storme. And a rotary switch for 2H, 4H and 4L.

(There is one additional lever in the SFX, but its gone, for good & I am not bothered now.)
The gear lever is mechanical way of shifting gears in the transfer case, and the rotary knob is the electrically actuated way.
Quote:
I don't plan any OTR's. Just normal off road scenarios one comes across while commuting.
Then you really wont need the diff-locks.
Quote:
SS-T & others - From 4L mode, to go back to 4H or 2H, I need to reverse a bit, after moving the lever to the desired position (4H, 2H & the light on the console goes off?)
Well, not really. You have to be stationary. However, if there is a drivetrain wind up (by driving in 4WD in tarmac, with good grip), then yes, you need to reverse and forward for easy engaging of gears and to free the locking hubs.
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Old 10th December 2013, 18:50   #251
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Default Re: Driving all four wheels: how is it done?



Was going to book an XUV FWD until i saw this video. Now, considering off-roading is not in the list of things i would do with the car, does the AWD version of the XUV have considerable advantages over the FWD in terms of handling and safety? Also Both AWD and FWD versions have ESP which aids emergency steering.

Please advice.
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Old 22nd September 2014, 12:04   #252
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Default A technical 4x4 question on diff. locks and capabilities of Fortuner vs. Scorpio

First my assumptions:
1. Scorpio 4WD has two differentials and in the 4WD mode, the rear differential gets locked.

2. Fortuner has three differentials and in the 4WD mode, the central differential gets locked.

3. Just for comparison, an AWD like BMW X5 has three differentials (and lots of other xDrive gadgetry) but none of them gets locked as there is no "dedicated" 4WD mode.

Now, here is the situation: a SUV gets stuck on a narrow village road with the right two tyres on the tarmac and left two tyres in a deep and soft slushy paddy field.

Here is a crude picture depicting the same.


Driving all four wheels: how is it done?-4x4_stuck_in_paddy_field.png



Now the question is: in which car will be it be easiest to get out of this mess? Here is my attempt to answer this question based on my very limited knowledge and experience.

1. Fortuner. On locking into 4WD mode, the central differential gets locked but the front and rear differentials are still open. So the front and rear left tyres spin and the cars doesn't move.

2. Scorpio. On locking into 4WD mode, the rear differential gets locked(the front differential is still open). So the front and rear left tyres spin but the right rear tyre gets some traction and it can possibly pull the car out of this situation (depending on how deep the slush is and how high the tarmac "wall" is)

3. Other AWDs like BMW X5: No differential lock can happen and the car remains stuck.


Please let me know if I have understood this correctly. Theoretically, a similar situation may happen on a water crossing in the HP if two tyres on one side lose traction?
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Old 22nd September 2014, 12:11   #253
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Default Re: A technical 4x4 question on diff. locks and capabilities of Fortuner vs. Scorpio

Scorpio 4WD doesn't have any lock in the rear differential. So none of them get out of the situation you have described.

But Safari 4WD and Endeavour 4WD do have rear LSD, they have better chance at getting out.

Last edited by Samurai : 22nd September 2014 at 12:13.
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Old 22nd September 2014, 12:24   #254
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Default Re: A technical 4x4 question on diff. locks and capabilities of Fortuner vs. Scorpio

Quote:
Originally Posted by gragusha View Post


3. Other AWDs like BMW X5: No differential lock can happen and the car remains stuck.
If the X5 has LSD in the rear, and if one of the rear wheel is on the tarmac, it can come out.
AWDs like Forester are claimed to come out of slush even if any one of the wheel has traction.
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Old 22nd September 2014, 13:07   #255
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Default

Quote:
Originally Posted by Samurai View Post
Scorpio 4WD doesn't have any lock in the rear differential. So none of them get out of the situation you have described.

But Safari 4WD and Endeavour 4WD do have rear LSD, they have better chance at getting out.
Hi Samurai - I thought that in part time 4WD SUVs, when you engage the 4WD then two things happen -
1. Power is transferred to all four wheels
2. Rear Diff is locked

Based on your post I had two questions:
1. I understand you correctly then a Scorpio just transfers the power to all the wheels. Since there is no central differential, it works like a central diff. lock?

2. Apart from the Jeeps, Thar etc, is there any SUV in India (in the 10-30L range) that provides rear differential lock capability?

Sorry, if I sound stupid - I don's have deep knowledge or experience of this stuff.

Quote:
Originally Posted by Guna View Post
If the X5 has LSD in the rear, and if one of the rear wheel is on the tarmac, it can come out.
AWDs like Forester are claimed to come out of slush even if any one of the wheel has traction.
Well this happened to the X5 and ultimately had to be pulled out by a tractor. I guess the only thing that worked under these conditions in the LSD was the "S" part!

(How I got into this situation is somewhat stupid and embarrassing!)

Last edited by Samurai : 22nd September 2014 at 13:15.
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