Thread: Is my Traction Control working???

If any of you have a CDL equiped D2 with no lever when you go off-road find a bank or similar to drive up (to give yourself room) get underneath and lock that CDL with a 10mm spanner.You will be pleasantly surprised just how much better you go with the CDL locked.Keep the motor running whilst doing it as a full restart disables your TC/ABS,a stall is OK it wont cause the TC/ABS to disable.
Build your own CDL lever or buy a kit,well worth the $$$/time to get a heap more off-road capability.
Andrew

Thanks again,

As a result of what you’ve told me I posted another question in this forum http://www.aulro.com/afvb/discovery/...covery-ii.html As a result, I’ve decided a genuine D2a Hi/Lo CDL lever from a D2a is the only way to go. I’ve found a supplier (4x4Discovery.com.au - "think outside ...") who is going to confirm price and availability in due course.

I’ll post a new thread with all the confirmed details when I get them.

Milney

The techniques required to negotiate cross axle type obstacles in a Disco II can seem counter-intuitive to someone that has learned in a normal 4wd. In a regular 4x4, spinning wheels and loss of forward momentum dictate backing off the throttle & trying again, lest you dig yourself a bigger hole with your spinning wheels.

The traction control system of the D2 operates by comparing the rotational speed of each wheel with the average rotational speed of all wheels. If any wheel rotates significantly faster than the average, the system applies the brake to that wheel to transfer torque back to the wheels that need it.

In a cross axled situation, any 4x4 will come to a stop, even the D2. A regular 4x4 would require backing off & trying again, but the D2 can drive through if the right technique is applied.

If you use light throttle, the free spinning wheels will spin slowly and the traction control only activates hard enough to slow the free spinning wheels below the activation threshold.

This is where the counter intuitive part comes in. Feed in more power and the free spinning wheels spin much faster than the average rotational speed of all the wheels. The traction control will activate the brakes much harder on those wheels and hence useful amounts of torque are transferred to the wheels on the ground.

I have easily driven through many a cross axled situation with this technique. Try it & you will see. The trick is to induce enough difference in wheel speed to get a robust application of the traction control. This system of getting traction to the ground is not exactly track friendly though. For this reason alone I have now fitted the CDL linkage to my D2, NOT because it couldn't negotiate a cross axle obstacle.

It should be noted that a centre diff lock WILL NOT get you any further in a cross axle situation. Anyone with knowledge of the theory behind diffs & 4x4 systems will understand this. Without the aid of traction aids like traction control or front or rear diff locks, if one front and one rear wheel is in the air, then NO torque will be transferred to ground. All that a centre diff lock means is that two wheels, rather than one, must be free spinning to lose forward drive.

Believe it or not, after all this time, just as you SmokyBear have posted your thread, I’ve today received an email from Ashcroft Transmissions in the UK who can supply the CDL lever for a really good price. I’ll also be to 4X4intelligence.com.au for recovery points, a lift and a few other things.

Thanks SmokyBear for the info. On the occasions I’ve been stuck I HAVE reduced revs and tried to reverse out as you have indicated many people do. What you’re saying simply is that next time I should bag ‘em up!?!?!?!?

Cheers,

Milney

Well, don't bag it up, just don't be afraid to gently feed it a little more juice : )
You will feel the traction control grab the brake on the spinning wheels, and the car will almost "walk" forward off the obstacle.

Try feeding different amounts of power, you will soon get a feel for how much is needed to get the traction control to do it's job.

I was lucky enough to secure the cdl linkage from an '04 model for $385 and it's certainly much more track friendly.

Originally Posted by Franz

The omission of CDL was major msitake by Land Rover (as evidenced by it's reintroduction in the 03MY) and makes the vehicle downright dangerous if reversing down a steep slope (I have a video of this somewhwere and the results are frightening)

This is the very reason that Landrover introduced their Hill Descent system.

In an all wheel drive vehicle with open diffs all round, it only takes ONE slipping wheel to lose all motive power. Likewise, in a hill descent situation, it only takes ONE slipping wheel to lose ALL engine braking effect.

Without a locking centre diff, it is therefore necessary to use traction control to fix the first situation, and hill descent control to remedy the second.

With the centre diff lock engaged the front & rear axles are locked together (just like a normal 4x4) and it takes both one front and one rear wheel slipping to lose either forward motive power or engine braking.

With a CDL engaged it is therefore quite possible to descend a steep hill without HDC, but it is certainly still useful, especially with an auto transmission.

I think it was the other way round actually, LR got a bit cocky with their HDC etc and felt a CDL was redundant.


Of course they was wrong...

Hi I just noticed tonight that my CDL light is coming on when I brake.
is there something specific I should look for to rectify this ? I have the model wihout the CDL Linkage fitted

I have a Nanocom but have had problems down loading the ABS and other updates so its back to basics for me .

Thanks in anticipation
George