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Old 21st September 2008, 23:25   #106
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Originally Posted by Motocoorg View Post
His name is Aiyanna, these guys know jeeps like back of thr hands and have some serious skills .
Hmm, is this the same Aiyanna who once went head-on against an elephant with just a knife?
(the elephant apparently backed-off ).
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Old 22nd September 2008, 07:56   #107
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Gurkha can survive even with 3 wheels spinning, but here all four wheels were spinning.
How come, does it have a centre diff too? Else it is sure to get bogged down!
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Old 22nd September 2008, 08:01   #108
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How come, does it have a center diff too? Else it is sure to get bogged down!
Why does Gurkha need center diff? Center diff (with LSD) is useful for driving on-road with 4x4 engaged. Off the road center diff is a liability. That's why GV has the option to lock the center diff while going off-road. No-center-diff is same as locked center diff.

Last edited by Samurai : 22nd September 2008 at 08:02.
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Old 22nd September 2008, 08:08   #109
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OK, but if 3 wheels are stuck and spinning, then one wheel is not enough to power the vehicle with or without centre diff, IMO, unless you are on ROCKY terrain!
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Old 22nd September 2008, 08:13   #110
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OK, but if 3 wheels are stuck and spinning, then one wheel is not enough to power the vehicle with or without centre diff, IMO, unless you are on ROCKY terrain!
With both diffs locks and no center-diff, you will get 25% power on each wheel irrespective of their status.
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Old 22nd September 2008, 08:24   #111
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agreed, but that ain't enough to get you out of slush!
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Old 18th June 2009, 15:59   #112
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Sear Sharath ( Samurai )

Got an opportunity to read the article and see the pics only today. Coorg is a beautiful area. I long for an oportunity to drive in this scenic area along the forest trails. That would be some fun.

Diff Locks.

Full time 4WD vehicles come with central diff locks.
My Landcruiser Prados had Central diff locks. Central Diff lock engaged is used only offroad in soft ground. With the central diff locked 50 % of the power goes to the front and rear axles.

In sand in Central diff lock is not engaged, once any wheel lifts, particularly a rear wheel where there is an LSD, the free wheel with no traction will start whirring with a zipping sound as all the power of the rear axle is transferred to it by the LSD.

When Central Diff lock is engaged this stops.

Vehicles with a rear diff lock instead of LSD are better in serious off road situation. Here 25 % power goes to each of the rear wheels and any wheel grounded will pull the vehicle out.

Some Landcruiser 80 Series vehicles had a front diff lock too, this once engaged would similarly pull the vehicle out of bad stucks.

The trip was fun I can see that. Would have loved to be on it.

Due to previous inexperience I can see too many people huddled close to the stuck or rescue vehicle.

In one picture there is even a camera on a tripod right next to a winch cable. This is dangerous.

If a 50 m winch line has been pulled out, all standers by must be pushed back atleast 50 m , a radius of 50 m must be absolutely clear of people. A winch cable god forbid if it snaps then with a 6000 lb load on it , it can cut a human being in two pieces. This has happened before. It is always adviced to put a towel or blanket on the winch cable to bear a downward weight on it and prevent it from flying upwards.

The person winching a stuck vehicle should also take the remote unit and winch from inside his vehicle. The windscreen will protect him from a snapped cable.

I saw a picture of the tyres on your Jeep. In that slush and stream, your tyres would get bogged because of mud clinging in the grooves. If such terrain is to be encountered nothing does better than an NDMS of A/T tread tyre like Micky Thopmson or NIKKO.

Also if a winch is used with a tackle block, the rescue will be much simpler and faster.

I was not surprised that a CJ3B with a Hurricane Petrol Engine and an experienced driver made it across the stream. It is one of the best vehicles for these situations.

You guys had a rocking trip. Wish I too could get to go on an OTR like this one.

With best regards,

Shahid
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Old 18th June 2009, 16:52   #113
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Thanks for your remarks desertfox.

Quote:
Originally Posted by desertfox View Post
Full time 4WD vehicles come with central diff locks.
My Landcruiser Prados had Central diff locks. Central Diff lock engaged is used only offroad in soft ground. With the central diff locked 50 % of the power goes to the front and rear axles.
My Grand Vitara is a full time 4WD with LSD + central diff locks. If your prado didn't have central LSD, how can it be fulltime 4WD?

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Originally Posted by desertfox View Post
In sand in Central diff lock is not engaged, once any wheel lifts, particularly a rear wheel where there is an LSD, the free wheel with no traction will start whirring with a zipping sound as all the power of the rear axle is transferred to it by the LSD.

When Central Diff lock is engaged this stops.
I am confused here, if you have rear LSD, how can all power transfer to the zero-traction wheel. There should be only limited slip (hence the name LSD), not 100% slip. Anyway, in case of GV locking won't work since both front and rear diffs are open, no LSD and no Diff locks. The wheel without traction will spin away to glory.

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Vehicles with a rear diff lock instead of LSD are better in serious off road situation. Here 25 % power goes to each of the rear wheels and any wheel grounded will pull the vehicle out.
Agree, but in India rear diff locks is a custom job except for Gurkha. I am not considering imported offroader here.

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Originally Posted by desertfox View Post
Due to previous inexperience I can see too many people huddled close to the stuck or rescue vehicle.

In one picture there is even a camera on a tripod right next to a winch cable. This is dangerous.
That's Jammy at the Tripod.

Quote:
Originally Posted by desertfox View Post
I saw a picture of the tyres on your Jeep. In that slush and stream, your tyres would get bogged because of mud clinging in the grooves. If such terrain is to be encountered nothing does better than an NDMS of A/T tread tyre like Micky Thopmson or NIKKO.
It is Apollo Storm AT tyres, similar to BFG TA/KO, the clayish mud makes it look like a sleek tyre. Most of us drive far distances to attend OTRs, that means we can't go full MT on our tyres, so we compromise with AT tyres.
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Old 19th June 2009, 17:03   #114
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Both my Prados and the Landcruiser VXR are full time 4WD. They have Central diff locks but the Central diff lock is not LSD. It is a normal central diff.

In the Prado Central diff lock is engaged by pushing the transfer case lever forward. The vehicle is always in 4 H. During normal running varying amount of power is transferred to front or rear axle as per terrain. Once Central diff lock is engaged, 50 % Power goes to each axle. In the Landcruiser it is done through an electronic switch to the right of the steering wheel.

The Prado has LSD in the rear differential. While negotiating dunes, if Central diff lock is not engaged all the power is transferred there and the wheel starts spinning and zipping.

Once central diff lock is engaged 50 % power goes to the front wheels which remains more on the ground due to engine weight. Only the power of the rear axle will go to the free wheel when only three are touching the ground and will prevent the zipping.

On the Fj cruiser the problem is solved with a rear diff lock instead of LSD, this is the reason it is the most capable desert machine. On landcruisers all three options are available. No diff locks, LSD or rear diff locks.

A rear diff lock can be fitted on Prado by Toyota instead of an LSD, a lot of serious offroaders have done this, then the SWB Prado becomes a world beater.

The Prado with its original Central Diff lock and LSD is very very capable on the rocks however.

When I launched the new Landcruiser 200 for Toyota I tested the KERR they have introduced in the topmost VXRmodels.

Once KERR is engaged, the driver just sits there controlling the steering while the vehicle acceleration and speed is decided by the ECU as per control, I engaged it on a dune descent which was not as good as manual 2nd or 1st gear selection in 4 H but on a bit of rocky ground when I applied it, I could actually drink a coke while the vehicle drove itself. Futuristic and OK for Gizmos, but I will never use these gimmics in actual tough off road situations.
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Old 20th June 2009, 08:05   #115
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Originally Posted by desertfox View Post
When I launched the new Landcruiser 200 for Toyota I tested the KERR they have introduced in the topmost VXRmodels.

Once KERR is engaged, the driver just sits there controlling the steering while the vehicle acceleration and speed is decided by the ECU as per control, I engaged it on a dune descent
Sir, what is KERR? Can you elaborate further on that Gizmo?
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Old 21st June 2009, 16:12   #116
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Simply put it is an electronic effort free rock and offroad automatic drive system developed by Toyota for their Landcruisers and perhaps Lexus 570 and top end Sequias to sell as a Gizmo. Now that hydlaulic lifting suspenson that lowers down to seat women and elderley passengers is no longer an option, this new gizmo is on offer

Practically it amounts to nothing.

An important consideration however is a switch to cancel deployment of airbacks in case of a hard knock offroad which is quite possible.
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