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View Poll Results: Diff locks or Articulation, what do you choose?
Diff locks - I think they are more important than articulation 21 61.76%
Articulation - With excellent articulation, diff locks are not really needed 13 38.24%
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Old 25th March 2010, 22:03   #76
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Quote:
Originally Posted by ex670c View Post
Hi ADC,

Locker - Auto-Locker/Dog Clutch LSD/Aussie Locker/Lokka
Diff-Lock - Selectable (On/Off) ARB/OX/ECTED

Regards,

Arka


Quote:
Originally Posted by ex670c View Post
Even if the Differential is the Same the front is weaker Due to
i) Steering Components i.e Steering Knuckle
ii) UJ & CV Joints
iii) IFS

If the Front Diff is Locked then with an LSD in the Rear the Front Diff will provide more traction and end up doing more work, which it shouldn't, including steering and then you can guess where what will happen especially with an IFS and the additional UJ & CV Joint.

Hello Arka

Exactly the worries have been reflected and written quite convincingly in this article about why no front locker in IFS.

Front Locking Differentials - 4Wheel & Off-Road Magazine


And again conversely and convincingly the FAQ section of Lokka is absolutely to go ahead with a front locker particularly for a IFS.

4WD Systems | LOKKA FAQ | Gear to Goannawhere


Quote:
Q7. Which end should I fit first? (if buying one)
This is dependent on the vehicle, its existing diff types, the type of suspension system and the model availability. However the front is usually the first choice.

a. If the vehicle is an IFS (Independent Front Suspension) model then the front fitment will result in the greatest increase in 4WD ability. This is because all IFS vehicles have very limited suspension movement (hence limited wheel travel and articulation) resulting in easily lifted wheels and total loss of front traction. Fitting a LOKKA to the front will solve this serious deficiency. (Pajero, Isuzu, 4Runner, B2600 etc)

b. If a vehicle has a good quality LSD in the rear, then a front fitment will obviously provide the best total traction ie one locker and one LSD is better than one locker and one standard diff. (GQ)

c. If a vehicle has a poor quality LSD then the issue becomes less clear and personal preference or ease of installation often become the more important criteria. However one LSD and one locker is still a better choice - if that is possible. (Landcruiser, Hilux, F100/150)

d. If the vehicle is a constant 4WD then a rear fitment is the easiest and best solution (Landcruiser 80,100 series etc)

e. A front fitment will actually yield the greatest improvement in off road ability. This is because, most vehicles require the increase in traction (that a locker gives) when hill climbing. Under hill climbing conditions, due to the angle of the vehicle, the rear wheels are carrying a much greater weight (weight transfer) and the front wheels are therefore carrying a lessor weight and tend to break traction very easily. Once one front wheel starts to spin, the other front wheel stops turning and the whole front diff ceases to provide traction. At this point all load is transferred onto the rear as if it were a 2WD and due to the increased load the rear wheels are encouraged to spin and the vehicle stops.
If you can solve the problem of the front wheels spinning, you have solved the traction problem. Another advantage is that on road there are no changes to normal driving characteristics at all.

Q8. Will it affect my steering?
Unlike manual lockers which do not provide differential action when locked and severely hamper steering and directional manoeuvrability, LOKKA's smooth sensitive operation allows differential action resulting in almost uncompromised steering irrespective of uphill or downhill, soft or hard surfaces. This means you can select the best path and negotiate tight bends easily. You can feel a mild tightening in the steering wheel which is a result of having both front wheels biting into the terrain driving more equally and occasionally on hard surfaces the effects of front to rear tailshaft windup (which happens anyway) and may lose some degree of turning circle under some situations. There will be a self centering effect on the steering wheel in sand and offroad track driving.

The front fitment is one of the single biggest advantages over manual lockers and is the reason why LOKKA is not susceptible to the drive line failures and wear present with manual lockers.

Other than that, as searched on net, people are divided all through about locker [selectable or auto] plus IFS.
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Old 26th March 2010, 11:20   #77
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Default Conclusion

Quote:
Originally Posted by adc View Post
Exactly the worries have been reflected and written quite convincingly in this article about why no front locker in IFS.

Front Locking Differentials - 4Wheel & Off-Road Magazine


And again conversely and convincingly the FAQ section of Lokka is absolutely to go ahead with a front locker particularly for a IFS.

4WD Systems | LOKKA FAQ | Gear to Goannawhere

Other than that, as searched on net, people are divided all through about locker [selectable or auto] plus IFS.
Hi ADC,

Since you have so convincing placed both arguments, please conclude this discussion.

i.e fixing an Auto-Locker in the Front IFS differential.

i) Is it worth the gain in traction.
ii) Reliability.
iii) Is it possible to keep driving keeping in mind the IFS & Locker Effect.

Regards,

Arka
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Old 26th March 2010, 14:44   #78
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Quote:
Originally Posted by ex670c View Post
Hi ADC,

Since you have so convincing placed both arguments, please conclude this discussion.

i.e fixing an Auto-Locker in the Front IFS differential.

i) Is it worth the gain in traction.
ii) Reliability.
iii) Is it possible to keep driving keeping in mind the IFS & Locker Effect.

Regards,

Arka

Hello Arka

Having read [since most probably everyone is on theoritical now on front lockers and front LSD], these are the conclusions.



Quote:
i) Is it worth the gain in traction .
Yes it is and I will take this reasoning word to word from Lokka FAQ and has been corroborated by the majority out there who are moving on with IFS and lockers [selectable or auto]. From an OTR viewpoint, someone with a front locker will surely leave a mark.

Quote:
A front fitment will actually yield the greatest improvement in off road ability. This is because, most vehicles require the increase in traction (that a locker gives) when hill climbing. Under hill climbing conditions, due to the angle of the vehicle, the rear wheels are carrying a much greater weight (weight transfer) and the front wheels are therefore carrying a lessor weight and tend to break traction very easily. Once one front wheel starts to spin, the other front wheel stops turning and the whole front diff ceases to provide traction. At this point all load is transferred onto the rear as if it were a 2WD and due to the increased load the rear wheels are encouraged to spin and the vehicle stops.

If you can solve the problem of the front wheels spinning, you have solved the traction problem. Another advantage is that on road there are no changes to normal driving characteristics at all. [this most probably will be a sales pitch, one has to use to find out
Quote:
ii) Reliability.
With improving techonology, reliablity is only increasing. Of all the brand names you have given, Lokka seems to be getting the maximum "traction" with the 4wd people due to cost-benefit vs the disadvantages.


Quote:
But, for most casual 4WDers, the benefits of the Lokka/SoftLocker, coupled with the lower cost and lack of any required future maintenance (outside of regular diff maintenance) is the winner. Given that the way it works can actually be more beneficial offroad (in that you retain your steering ability with it locked), it's a shame that they're seen as the poorer cousin of the AirLocker.
Quote:


iii) Is it possible to keep driving keeping in mind the IFS & Locker Effect.
With front Locker installed [auto or Selectable], crawl mode is guarranteed because you care for the vehicle more than the photop, and in the slow mode the thinking process is more faster. With a locker, the responsibility make one to go slow and think over an obstacle rather than push it up in air through momentum.

Quote:
Originally Posted by adc
with selectable locker [diff lock], I am seeing the terrain, thought process is there and then selecting it as and when necessary, most probably in very short bursts of few seconds duration.




As for LSD at front, the benefits are less, steering will be a problem in thin ice and slimy mud. Not for touring purposes when we get this kind of road.

Do Diff locks compensate for lack of articulation?-img_3687ee.jpg

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Quote:
Try smooth shiny packed snow, or ice. The front wants to go straight. The rear doesn't want you turn either. There isn't enough traction to force the LSDs to slip, so it's just like having lockers fully engaged - initially it fights your turn, then the front tires - BOTH of them - break loose. Since the rear has an lsd too, you continue going straight.

Having something in the front but not in the rear doesn't work either, because when you turn the wheels the track radius difference still causes the front tires to break loose.

I learned 2 things - drive VERY gently, and to "pitch" it into corners, sort of letting the rear end drift around, then getting on the gas (gently) and getting it to carve the turn like a rally car does.

Even going in a straight line you could lose traction on icy roads, all 4 wheels just loose their grip together and you slowly slide off towards the shoulder.

Best thing you can have when it's really slippery is open diffs front and rear. Excellent control. You need that more than traction
All said and done, and as per "my" conclusions:


1. A selectable locker would be great at front but with careful use - for once in while use or in short burts looking at the terrain, but the cost is quite a lot

2. Definitely not an LSD at front.


3. The best middle point is autolocker [Lokka] thinking about the cost and disadvantages.


4. As a tourer - Not to do anything at the front - not a locker or surely not a LSD. Selectable locker would have been good but costs thrice the money of a auto locker.


So, for me, reading other peoples experiences, the practical decision on our context :

For touring - Rear Auto locker and open diff.

For OTR in sports mode and having the funds - Rear LSD and front selectable lockers used in short bursts when needed. With no funds, at least the autolocker


Again, people are divided right in the middle about what to do at the front.

Last edited by adc : 26th March 2010 at 14:59.
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Old 27th March 2010, 00:19   #79
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My comments in bold.


Quote:
Originally Posted by adc View Post
Hello Arka


All said and done, and as per "my" conclusions:


1. A selectable locker would be great at front but with careful use - for once in while use or in short burts looking at the terrain, but the cost is quite a lot- Agreed

2. Definitely not an LSD at front.- Okaaay


3. The best middle point is autolocker [Lokka] thinking about the cost and disadvantages.- So are you saying that an auto locker is the middle point between LSD and an Selectable locker?

That is a wrong assumption. The the LSD (viscous coupling) will release a lot sooner than your auto locker will.

The only difference between an auto locker and a selectable locker is ..well, it is selectable.


4. As a tourer - Not to do anything at the front - not a locker or surely not a LSD. Selectable locker would have been good but costs thrice the money of a auto locker.- Agreed.


So, for me, reading other peoples experiences, the practical decision on our context :

For touring - Rear Auto locker and open diff.

For me it would be Rear Selectable locker and open diff or if I can't afford it, Rear LSD and open diff. Having a rear locker for touring will put unnecessary strain on the rear diff in the long run because it is always engaged.

For OTR in sports mode and having the funds - Rear LSD and front selectable lockers used in short bursts when needed. With no funds, at least the autolocker - I would go for Rear Auto locker and Front LSD.


Last edited by fiery enzyme : 27th March 2010 at 00:22.
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Old 27th March 2010, 16:33   #80
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Thanks FE, for carrying the discussion further.

Hope you all jeepers understand, No way should my doubts be taken as me being pompous or something negative. Definitely acknowledge and admire what all you guys are doing out at there, really nurturing the 4wd situation slowly and surely against all odds.

What prompted me these queries is feeling that the front [LSD or locked or selectable] throws some amazing probabilities and almost like the unknown frontier in 4wd offroading, and no particular one line answer is answering the questions. The input of the driver is limitless [thus the joys of offroading] with a front modfied.

Quote:
3. The best middle point is autolocker [Lokka] thinking about the cost and disadvantages.- So are you saying that an auto locker is the middle point between LSD and an Selectable locker?
That is a wrong assumption. The the LSD (viscous coupling) will release a lot sooner than your auto locker will.
Yes, if there is no active driver input and thought. But these are thoughts I agree with and how with a front LSD and a autolocker will be different.



Quote:
There is a problem with clutch-driven limited-slip differentials in IFS though, where the clutch-driven limited slip will constantly want to pull forward, more so even than an automatic locker that would disengage around a corner. This will make steering input difficult to say the least.

The best alternative you have for an IFS front would be a helical-gear-type limited-slip differential that will free up and allow you to carve a steering wheel back and forth.
Quote:
If you want an auto locker to steer, back off. The beauty of an auto locker is that it will differentiate.
Quote:
With autolockers, if you don't throttle into turns it is easy to get along with, but can bump, pop, clunk, or whatever adjective you wish
Quote:
Auto locker in mud and snow will allow operation with maximum traction [much better than LSD] while giving good steering.
So, backing off throttle with autlocker can be okay but biggest drawback is what happens in hill slope sideways, one cannot back off throttle.


Quote:
You can easily roll your truck on loose sand for example if you engage a locker the wrong time.
Quote:
So, for me, reading other peoples experiences, the practical decision on our context :

For touring - Rear Auto locker and open diff.

For me it would be Rear Selectable locker and open diff or if I can't afford it, Rear LSD and open diff . Having a rear locker for touring will put unnecessary strain on the rear diff in the long run because it is always engaged.
Absolutely, and I should have clarified more clearly. As said, for me, so what I have right now - a 2wd Safari. And what is available at OEM level for a 4wd Safari - LSD rear and open diff.

If I am able to afford a 4wd tourer, i.e, a 4wd Safari with LSD rear is the choice - coming from OEM means good tolerances and issues. i.e., I would not change anything.

But, for me the realiity is, with a 2wd Safari, and if with no funds to buy a 4wd even in 2 years, I would go for a rear locker once the extended warranty goes away [in another 1.5 years] to do somewhat extensive trail touring for sure.


So, yes, all lockers put extra strain on drive axles [may be not like the Gurkha as they are OEM and I assume Force Motors must strengthened the parts], but the effect is long term, and that is a trade off that can be taken since it is in rear axle and also long term.

With these heavy vehicles, somewhat of a slow crawl can be introduced rather than momentum and pedal power - the last two give more service centre bills and, my guess, is that I will be protecting more and loosing less by taking it slow and also covering more trails by the great traction [i.e. the trade off for hard touring, again as said for myself].



So in summary for practical purposes, As tourer for myself

1. With a 4wd + LSD rear and open diff i.e OEM - eg Safari

2. With a 2wd Safari, a rear locker and open front diff. ie. that I have.

3. With 4wd but no LSD from OEM - a rear locker and open front differential


Quote:
For OTR in sports mode and having the funds - Rear LSD and front selectable lockers used in short bursts when needed. With no funds, at least the autolocker - I would go for Rear Auto locker and Front LSD.
Here I was putting myself like what would have happened If I was very avid offroader [eg KS and his Gypsy] , i.e OTR in sports and very serious hobby and what would be my thought process like:.

1. A rear locker already there and great traction, what I am inferring from that post is that he is able to do some 60% of the inclines with the rear autolocker in 2wd, such is the traction.

2. Good sequence of modifications done - Tyres, GC, and finally the lockers.

3. An avid offroader [OTR as serious sport and hobby], No LSD and also would agree no autolocker too.

Save for as many years as needed, but a front selectable locker - the probabilities and satisfaction of OTR will throw up numerous combinations for all kinds of terrain with a selectable front locker with the rear autolocker already installed.


One important conclusion is like, locker modifications come at last, First tyres, GC, engine power and other body mofidications for clearence and then lockers. A vehicle which has lockers and lacking in others will be a disappointment to some extent.


Again just thoughts, and the amazing unknown nature of the front diff with [LSD/auto locker/selectable locker] and how a driver's judgment is becoming very important [always been] is fascinating to say the least!

Last edited by adc : 27th March 2010 at 16:50.
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Old 29th March 2010, 18:04   #81
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The FJ Cruiser from Toyota does rear lockable diff and traction control up front. Apparently it works well without compromising steering
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Old 29th March 2010, 20:42   #82
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Originally Posted by DKG View Post
The FJ Cruiser from Toyota does rear lockable diff and traction control up front. Apparently it works well without compromising steering
TRAC system of FJs are hugely complicated [ECU dependent] and what not. It works in tandem with VSC and wheel sensors, plus the brakes and that whats makes it such a proprietary product. It so efficiently complicated and what and how it does, people still cant decide even what it is doing after reading the manual, off course, as said, its a trump card for FJs and comes in the high end models.

Its so efficient that motorsports area people have made it illegal to TRAC system as it takes away every bit of individual driver input.

Attaching pages from the FJ manual about VSC and TRAC, ATRAC is what is more offroading tuned.
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Do Diff locks compensate for lack of articulation?-394982206_zlsd5xl.jpg
Do Diff locks compensate for lack of articulation?-394982386_fxxcixl.jpg

VSC plays the most important part in controlling ATRAC along with the ECU, sensors, - and the very interesting fact - TRAC/ATRAC is disabled in 4-Low.

As said, enthusiasts are still discussing on not how well they work but how they work.



As for selectable locker probabilities, we can test it ourselves out , may be, Gurkha having both diff locks [selectable], are most of them being used by the owners together, in tandem?

What happens if the rear is locked and the front is kept open for a particular incline terrain and just when at the top may be front locker is used intermittently?

How does the diff components have been holding with the both diff locks used. How the stress is distributed with diff locked, with torque - more of it going at the rear?

How it can be dangerous to have only the front locked and the rear unlocked for a particular terrain, as sudden torque to the rear wheels as it finds traction will put stress on the selectively front locked?

How diff locks can be used proactively or does it become too overwhelming for a driver with 2 selectable lockers?

Rhandle and Dr Mohan are the best to come out the different probablities and situations that can be made out of the 2 differential lockers. It would be interesting but again careful considerations have to be done so that it is not done in no slippage conditions [for the rear or front or both] or in a turning.

But again, a vehicle with only lockers and lacking in others will disappoint, but lets see how "selective" diff lock operation overcomes its low torque and slippage problems.

Last edited by adc : 29th March 2010 at 20:56.
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Old 29th March 2010, 22:23   #83
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Quote:
Originally Posted by ex670c View Post
Hi Sharath,


We guys can try an experiment.

1 Jeep & 1 Slope (A Stock FFRA CJ3B )

i) Climb up in 4WD-HI.
ii) Climb up in 4WD-HI Reverse.
ii) Climb up in 2WD-HI.
iii) Climb up in 2WD-HI Reverse.
iv) Climb up in 4WD-HI Front Axle (Rear Axle Disconnected).
v) Climb up in 4WD-HI Front Axle (Rear Axle Disconnected) Reverse.

Lets see which attempt is successful or most efficient.

Spike, Sutripta & Samurai and other Scientific Minds can add to parameters.

Regards,

Arka

PS - Since we have to remove the rear Prop-Shaft, I already have a volunteer in mind
Hi,
Back to TBhp after some time. Feels nice.

If by scientific, you mean one rusty brain (like the inside of old fuel tanks:- leading to sputtering and total stoppages), then yes, I'm your guy!

Just for this (climbing vertical wall)experiment, I would think a central diff would be a must, and also doing it in reverse in a LWB would be easier.

Does anyone know the F/R weight bias of the various WBs?


Quote:
Originally Posted by Samurai View Post
Spike, you are the numbers guy. Can you calculate the amount of the force needed to make the front tyre move up by the push of rear axle only?
The mid point of the vehicle will describe as locus a 90 deg arc with r=WB/2. Initially, the only work of the rear (as non climbing) wheels is to provide "downforce" for the front wheels.

Regards
Sutripta
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Old 31st March 2010, 07:00   #84
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the arc would be slightly less i guess, 90-2*taninv(gc/wb*2)...
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Old 31st March 2010, 11:55   #85
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Originally Posted by k!ng_@thur View Post
the arc would be slightly less i guess, 90-2*taninv(gc/wb*2)...
My reasoning: The midpoint of the line joining the two axles will move in a 90 deg arc.

Out today. Next discussion after one week!

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Old 3rd April 2010, 11:57   #86
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Default LSD vs TCS vs Diff-Locks

Hi Guys,

An interesting Video from 4WD Monthly.





Regards,

Arka
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Old 3rd April 2010, 12:35   #87
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Default Articulation vs Locker

Leaf Spring + Lockers vs Coil Spring vs Coil Spring + LSD

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