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Arctic



Member Since: 25 Aug 2010
Location: Europe
Posts: 45

Traction control or diff. locks?
I just watched a youtube video which compared various models of AWD cars on a ramp which simulated a loss of traction on the front wheel initially and then on three wheels. Although clearly biased towards Subaru, it did get me thinking and a few questions came to my mind, as follows:

-In a similar sitation, e.g. 3 wheels on ice, would the Defender (diff. locked and with traction control) be able to send enough torque to 1 wheel in order to move the vehicle up an incline?

-How much (%) torque can the Defender send to 1 wheel?

-Why have Land Rover chosen to use traction control rather than manually lockable front and rear differentials like Mercedes offer on their G wagon?

-Finally, any idea why the Defender doesn't have a centre differential that can vary the torque distributed to the front and rear axles like say the Audi Quattro or Subaru system? Surely this would make more use of the four wheel drive system in on-road situations when it is not possible to have the centre diff. fully locked. Or have I misunderstood how these systems work?!
Post #40412 13th Sep 2010 3:20pm
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mse



Member Since: 06 Apr 2008
Location: UK
Posts: 5034

United Kingdom 2016 Defender 110 Puma 2.2 XS CSW Scotia Grey
I suppose you can spend ours discussing this - im sure some will.

I personally never undersood why LR didnt put locking rear and/or front diffs on the defender as a cost option, i would have paid.

TC is a cheaper compromise. But dont forget the rest of the line up has locking rears.

However, i can say Defenders are one of the more capable off road vehicles ever invented...so you have to ask does it need it to the degree others do? Mike
Post #40414 13th Sep 2010 4:59pm
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johnnyturbo2002



Member Since: 21 May 2009
Location: Poniente Granadino
Posts: 371

Spain 2008 Defender 110 Puma 2.4 CSW Java Black
some time ago, one of our more intelligent gents put up a very nice and easy to understand graphic for us laymen to understand...sure it is still around to get our minds around it. 2008 Defender 110 60 year Edition (sold unfortunately)
IN the hunt for another Puma for the wifey!
2008 Kia Sorento LX 😁 2.5crdi
Post #40417 13th Sep 2010 5:36pm
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johnnyturbo2002



Member Since: 21 May 2009
Location: Poniente Granadino
Posts: 371

Spain 2008 Defender 110 Puma 2.4 CSW Java Black
and here it is
http://www.defender2.net/forum/topic2427.html

thanks to AndrewS...what a chap! 2008 Defender 110 60 year Edition (sold unfortunately)
IN the hunt for another Puma for the wifey!
2008 Kia Sorento LX 😁 2.5crdi
Post #40418 13th Sep 2010 5:39pm
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Arctic



Member Since: 25 Aug 2010
Location: Europe
Posts: 45

That was good, thanks. So, could you just confirm that max 25% of available torque can be sent to the one wheel with traction using the traction control system? Would this be sufficient for a loaded vehicle on an incline?
Post #40425 13th Sep 2010 6:45pm
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MK



Member Since: 28 Aug 2008
Location: Santiago
Posts: 2409

Chile 2007 Defender 110 Puma 2.4 SW Chawton White
Lockers need to be operated by drivers with some training and a Defender being a work vehicle, not all the time are driven by capable people. Also, Defenders not have the best quality drivetrain shafts. G-Wagen on the other side are unlikely to be used and abused as a Defender would. The exceptions are those with special specs for the army. Puma 110" SW

.............................................................
Earth first. Other planets later
Post #40435 13th Sep 2010 8:08pm
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Naks



Member Since: 27 Jan 2009
Location: Stellenbosch, ZA
Posts: 2633

South Africa 2010 Defender 90 Puma 2.4 SW Alpine White
The one issue with TC is that it is a reactive system, i.e., you must first lose traction before it engages, which sometimes is not so good. On the other hand, a locker ensures that you will have optimum traction before attempting an obstacle.

A Defender with a rear locker is a formidable offroader, I have seen what they can do and it is impressive - where a standard Defender needs some momentum, a Defender with a rear locker can idle through.

My previous landy was a D2 Td5 and the TC on that was impressive - when you lose traction, you simply keep your foot steady on the accelerator and 2-3 seconds later the TC engages and you crawl out of there without any fuss.

A number of SA guys are now putting KAM rear lockers on, they seem to be really good. I would get one if they weren't so expensive (-+R12K), but I don't do enough offroading to justify the expense!
Post #40437 13th Sep 2010 8:17pm
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bm52



Member Since: 04 Apr 2010
Location: Kent
Posts: 2189

United Kingdom 2014 Defender 110 Puma 2.2 XS CSW Havana
i was at Peterborough yesterday and went on the off road course and did all the red routes.

this was the 1st time i had taken my Puma properly off road, if you know what i mean.

i am certain that if i did the course in my previous 90 [a 300tdi] i would have been cross axled near the camera peeps and struggled a bit in one or two other places in standard mode, probably have to have used diff lock on one or two of the climbs.

the Puma with TC just poodled over anything there - it was almost too easy if you know what i mean. And yeah i appreciate that it was'nt the toughest of routes. But it was enough for me to see just how good the TC was and even when i tried a couple of the undulations on anti-stall it just carried on effortlessly .........and then is cruised 130 miles home without any fuss.

i am utterly sold on the Puma - as some of you said i would be when i was trying to make up my mind.

300tdi = huge respect, have one anyday
Puma = Bow down Bow down BM52
Post #40440 13th Sep 2010 8:36pm
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jst



Member Since: 14 Jan 2008
Location: Taunton
Posts: 7992

 2011 Defender 110 Puma 2.4 USW Stornoway Grey
you can send 50% of torque to one wheel with middle diff locked and TC stopping the other wheel on the axle rotating.

remember on the Def TC works across axles not over all 4 wheels so if Difflock is not in you could loose momentum with just one axle having two wheels turning at the same speed and the other axle wheels doing nothing.

As mentioned axle lockers require some knowledge of when to use them, maybe there is a liable point there as to why a front locker isint offered on any LR? That along with chocolate drive trains especially when big wheels are added.

Andrews pics are from LRE - try a course if you dont understand all the in and outs of how to make the most of your defender off road, including how to make the most out of TC.

the 50/50 split is a manual pre empted move by the driver to engage diff lock. to have a different split to improve on road driving such as suggested you would need electronics to control the middle diff and degree of 'lock up' - ie TR and DSC control systems. i wouldnt want that on my defender. Remember the market that the def is aimed at. Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop
Post #40538 15th Sep 2010 8:46am
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Arctic



Member Since: 25 Aug 2010
Location: Europe
Posts: 45

Thanks for all the replies, it makes a lot more sense now. Doesn't Audi use a mechanical (torsen) system to send torque to either the front or rear, as required? That said, it is of course not designed for an off-road vehicle.
The mechanical difflock makes sense for a Defender, though, as said, I would have expected them to have offered at least a mechanical rear difflock as an option long ago. I suppose TC takes care of it now though. Is this still an option or standard on all new Daefenders these days?
Post #40543 15th Sep 2010 9:30am
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Naks



Member Since: 27 Jan 2009
Location: Stellenbosch, ZA
Posts: 2633

South Africa 2010 Defender 90 Puma 2.4 SW Alpine White
jst wrote:
remember on the Def TC works across axles not over all 4 wheels


Incorrect, I have had TC intervene when driving on a gravel road without CDL locked Wink
Post #40545 15th Sep 2010 9:47am
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jst



Member Since: 14 Jan 2008
Location: Taunton
Posts: 7992

 2011 Defender 110 Puma 2.4 USW Stornoway Grey
Naks wrote:
jst wrote:
remember on the Def TC works across axles not over all 4 wheels


Incorrect,


sorry i should of clarified it more, pre11MY def it works across each axle, post 11MY it works on all 4 wheels.

Naks wrote:
jst wrote:
remember on the Def TC works across axles not over all 4 wheels


I have had TC intervene when driving on a gravel road without CDL locked Wink


i didn't say it only worked with CDL locked i said it worked across axles. think about it - it doesnt need the CDL locked to come on to work across an axle. Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop
Post #40551 15th Sep 2010 1:01pm
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mse



Member Since: 06 Apr 2008
Location: UK
Posts: 5034

United Kingdom 2016 Defender 110 Puma 2.2 XS CSW Scotia Grey
Im sorry i dont agree - i understand and have experienced TC working on all 4 wheels on all MY's Mike
Post #40589 15th Sep 2010 11:22pm
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jst



Member Since: 14 Jan 2008
Location: Taunton
Posts: 7992

 2011 Defender 110 Puma 2.4 USW Stornoway Grey
i understand forums and i understand people don't and shouldn't take things at face value and should always question. So i will attempt to explain using my job, this one and last one for 6 years, plus pre production work we completed on 11MY TC systems.

TC will work on all 4 wheels. what i am saying is that it only senses across axles on pre 11MY. so:

CDL unlocked;

front axle left is spinning, TC will brake the front left to divert power to the front Right. regardless of what the rear is doing. the rear axle wheels could be stationary and no TC working. all the power is taking the easy route through the mid diff to the front diff. TC is then splitting that power at the front diff. (power being used as a generic term)

or the rears could say have right hand wheel also spinning, in which case TC will brake rear right and divert power to rear left. TC is working and it is working on all four wheels but it is not sensing the speed differences between front and rear axle wheels.

to continue this same example, therefore, if the front TC interacted and ended up with both front wheels doing say 5mph, the rear could of interacted and ended up with the rears wheels both doing 10mph. there is nothing to (pre 11MY) to make them all do the same speed from a TC perspective. (TC aims to have the wheels turning at the same speed within tolerances, the system obviously allows for turning corners, hence the delay at slow speeds when you loose traction before TC cuts in, you need to exceed the expected turning speed of one wheel for it to be going around a corner at a set engine speed)

The reason the original system was across axle only was the CDL, this should be engaged prior to conditions where you feel you may loose traction. you then get power 50% power front and rear. the TC is still working across each axle, but these are now joined by the CDL will mean all 4 wheels will have TC interaction as required to turn them all at the same speed.

On your loose gravel tracks or wet tarmac you can still get TC working. see the first para example. Go into a corner, loose traction on a front wheel as you apply power and TC will cut in. There is no CDL locked then.

on 11MY defenders the TC senses speed across all 4 wheel stations, such as D2, T5 platform and LR2s. It is therefore more efficient as it does not need the CDL to be locked as it can mimic this, granted from a reactive point of view. Use of the CDL is a preventative measure.

Now i am beyond caring if you dont agree or say incorrect. Very Happy Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop
Post #40609 16th Sep 2010 8:32am
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MK



Member Since: 28 Aug 2008
Location: Santiago
Posts: 2409

Chile 2007 Defender 110 Puma 2.4 SW Chawton White
Trying to address the original question, here is a video:

http://www.arbchile.com/air-locker-vs-lsd-vs-traction-control/

Thumbs Up Puma 110" SW

.............................................................
Earth first. Other planets later
Post #40611 16th Sep 2010 10:08am
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