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Old 27th August 2013, 15:01   #226
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by Sutripta View Post
I wonder what it is about the Fortuner that makes most owners hypersensitive?

Anyway, right from the start we have been 'told' that the our Fortuner comes with a Torsen centre diff. Till now, it has never been questioned, so has been accepted on faith. And with passage of time without challenge, that faith grows. Now that it has been questioned, it needs to be resolved.
Why does it matter much either way?! It isn't like it makes the vehicle hugely more or less capable. It is just another mechanical version of a lockable center diff. A little more advanced, is all.

What would be interesting is a comparison of the Fortuner 4x4 running gear with that of the current Landcruiser, a car in a very different league as far as off roadability is concerned. Or anything else for that matter.
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Old 27th August 2013, 17:21   #227
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by Sutripta View Post
...we have been 'told' that the our Fortuner comes with a Torsen centre diff. Till now, it has never been questioned, so has been accepted on faith. And with passage of time without challenge, that faith grows. Now that it has been questioned, it needs to be resolved. The 'I say, you say' method is not going to resolve the issue. And so far, that is all we have. From both sides.

Our 'operational tests' will not satisfy the diehard believers of whichever side comes worse off.
The following videos may offer some insights about the Indian Fortuner's centre diff and its LSD abilities. I presume the drivers haven't locked the centre diff.



And this is a South African Fortuner, where the driver seems to know what he is doing.


A Middle -Eastern Fortuner, definitely not stuck (nor stock!)
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Old 27th August 2013, 17:46   #228
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by SS-Traveller View Post
The following videos may offer some insights about the Indian Fortuner's centre diff and its LSD abilities. I presume the drivers haven't locked the centre diff.
Apart from the specs of the vehicles, driver skill and tyres would play a big role right?
  • Locked the central differential?
  • Reduced tyre pressure?
  • Right tyres?
  • Appropriate momentum?
The South African one would have a rear diff lock too.

Edit: in the first video, the driver - in spite of not being able to advance initially - went ahead, into wet soft sand near the water, at an angle! Literally digging oneself into a hole?

Last edited by nilanjanray : 27th August 2013 at 17:51.
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Old 27th August 2013, 17:55   #229
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by nilanjanray View Post
The South African one would have a rear diff lock too.
Does it - that's interesting. I would guess it would need a different axle, it isn't a simple matter to add/remove the diff lockers? How is it enabled - manually?
As to the Torsen center diff, I suspect that it would be cheaper for Toyota to standardise the center diff across the world for the Fortuner than to have variants. With/without Torsen - I don't know enough to fuel that debate.
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Old 27th August 2013, 18:11   #230
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by Sawyer View Post
Does it - that's interesting. I would guess it would need a different axle, it isn't a simple matter to add/remove the diff lockers? How is it enabled - manually?
As to the Torsen center diff, I suspect that it would be cheaper for Toyota to standardise the center diff across the world for the Fortuner than to have variants. With/without Torsen - I don't know enough to fuel that debate.
CDL is done through the same small lever present in our Fortuners. For RDL, there is a switch at the right.

I agree about standardization for the 4WD version.
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Old 27th August 2013, 18:14   #231
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by nilanjanray View Post
...the first video...
That's the most interesting one. Look at how a single wheel loses traction in sand - yet, there seems to be no torque transfer to the wheels of the other axle (no sand being kicked up at the other axle). Happens at least 3-4 times. Not expected for a LSD or locked centre diff.
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Old 27th August 2013, 21:36   #232
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by tsk1979 View Post
Fortuner everywhere in the world(4wd) has a LSD center diff. I doubt they will create something "special" for such a small thing.
The Fortuner is available for different markets with at least 5 different engines, 3 different gearboxes, and 3 different rear differential configurations. Why not more than one centre differential (especially when Torsens cost a whole lot more than regular open diffs)?
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Old 27th August 2013, 21:46   #233
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by SS-Traveller View Post
That's the most interesting one. Look at how a single wheel loses traction in sand - yet, there seems to be no torque transfer to the wheels of the other axle (no sand being kicked up at the other axle). Happens at least 3-4 times. Not expected for a LSD or locked centre diff.
A LSD is not a locker. It will transfer some torque. I also drive a LSD vehicle (rear diff is LSD). Often one tire is spinning freely while other tire is stationary.

Anyways, I guess its trivial for one of the owners to check and click a pic of the center diff.

Another way is to look at the Owners manual and see what kind of oil and what are the specifications in the owners manual.
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Old 27th August 2013, 22:07   #234
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Default Re: Driving all four wheels: how is it done?

Wow! a very healthy discussion and informative thread.

Thank you so very much as this is extremely useful for novices like me
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Old 27th August 2013, 22:20   #235
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by tsk1979 View Post
A LSD is not a locker. It will transfer some torque. I also drive a LSD vehicle (rear diff is LSD). Often one tire is spinning freely while other tire is stationary.
The limited slip differential in the rear axle of the Safari is a clutch pack type of LSD, whose behaviour when one of the sides is losing traction, is completely different to that of a Torsen LSD.

In a clutch pack type LSD, the faster spinning wheel continues to be fed all the torque, with the clutch trying to share a small percentage with the other side. With an LSD like yours, and with one tyre spinning freely, making it spin even faster can get you out of a stuck situation by forcing the clutch to grip more and transfer more torque (unless the clutch is worn out and can't grip any more).

Not the same with Torsen. The quantum of torque being delivered to the wheel that spins faster reduces at a fixed ratio in case of Torsen - a free spinning wheel means (approx.)0 torque on that wheel; so even if the Torsen transfers 5x the torque of the free-spinning wheel to the other side, 5x(approx.)0 is still (approx.)0 - not enough to move a >2tonne automobile.

I hope that explains Torsen and its (should I say it?) *quirks* a little better. As I was told right in the beginning of this thread,
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Originally Posted by Sutripta View Post
Quote:
Originally Posted by SS-Traveller (Driving all four wheels: how is it done?)
So what on earth is a Torsen limited slip differential??? I'll talk about it in the next post.
Good luck. You are a braver man than I.
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Old 27th August 2013, 22:48   #236
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Default Re: Driving all four wheels: how is it done?

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Originally Posted by SS-Traveller View Post
The limited slip differential in the rear axle of the Safari is a clutch pack type of LSD, whose behaviour when one of the sides is losing traction, is completely different to that of a Torsen LSD. ,
Thanks for the information. I guess now an owner can probably get under the vehicle and click a pic? However, if there is a protection plate, it may be more difficult.
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Old 29th August 2013, 12:04   #237
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Default Re: Driving all four wheels: how is it done?

Not sure if this is the right forum but I wanted to ask the experts a question. In rock crawling competitions in the US, before a tricky multi-boulder climb, the spotter attaches a snatch strap to the front tow hook and pulls down hard - from a safe distance of course. The theory is that even a 100 pounds of weight, will help keep the front wheels grounded so that the vehicle does not rear up, do a belly flop and ultimately beach itself. I was wondering if the same would hold true for the rock obstacles we encounter - like at TPC or the Bangalore OTR.
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Old 14th September 2013, 15:08   #238
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Default Re: Driving all four wheels: how is it done?

Wandering here into the debate a little late, but then...

About the Q of the central differential of the Toyota Fortuner here's the extract of the post I put up on Admiral's thread:

"And also got another point cleared - one which has been vexing some of the TBHPians.
Caught hold of the Chief Technician and asked him about the central differential system and also requested him to get the thick workshop manual. He got the manual and informed us that the Toyota Fortuner 4X4 has a Torsen LSD.
He then proceeded to show us the manual which read:
" Centre Differential Gear Type - Torsen 2 LSD."
Checked the underbellies of the two Fortuners and found that the TCs/centre diff units were exactly the same as well.

And so that's that."

And here's the link to Admiral's thread:
http://www.team-bhp.com/forum/long-t...sails-128.html (Fleet Admiral Togo Heihachiro - Toyota Fortuner. Life Sails On...)

Trust this clears the air !

Last edited by Guderian : 14th September 2013 at 15:24.
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Old 14th September 2013, 19:52   #239
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Default Re: Driving all four wheels: how is it done?

^^^
Pictures of the relevant pages of the manual and of the Xfer case would have been nice.
What about the parts catalogue?

Regards
Sutripta
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Old 1st December 2013, 18:08   #240
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Default Re: Driving all four wheels: how is it done?

I am going to read this thread as part of my home work. BTW, what does MLD mean? How it helps ?

Thanks
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