Diff lock vs. traction control

[David Anderson]

I've heard a lot of talk about traction control vs. diff locks in referance to the NT Pajero and always assumed the diff lock would be better for most things, but I came across a situation on a trip the other day where the traction proved better.

I was out with the Mudgee 4x4 club on a social trip with the kids in the Blue mountains and we came across this side track that had a couple fairly big sandstone steps - everything was also very wet.

The highly modded trucks went straight up and everyone ended up having a go with some help from the more experienced drivers in the club.
The second step (not really obvious in the shot) involved edging up to the lip and then easing up - pretty straight forward.

I locked the rear diff and went for it, but the back wheels couldn't quite manage and it was clear that it wasn't going to happen at low speed and without risking damage.
Out of curiosity, I unlocked the diff and tried with the traction control and it went straight up with just a slight chirp from the front.

Obviously not a scientific experiment, but interesting none the less.

[nj swb]

Thanks for the report - it's good to read first hand accounts of personal experiences.

I would argue this is a classic example of a rear diff-lock's weakest point. The front wheels were significantly unloaded, so there's very little weight left to flex the suspension. You don't say whether or not both front wheels were on the ground, but it's likely that one was either in the air, or very lightly loaded.

So the open front diff was doing next to no work, and the rear wheels probably couldn't grip real well on wet steep rock while trying to climb the step. Poor rear grip + very little (or no) drive from the front stopped your vehicle.

Once the traction control was allowed to work the front wheel with all the grip suddenly had a lot more drive, so the front end was able to pull the vehicle while the rears struggled on the steep bit.

I'd love to know how a front-only locked vehicle would've gone in the same circumstances, compared with the traction control.

[TheTaipan]

David I guess you have the factory diff lock. With the ARB the traction control is not turned of so problem solved. the best of both worlds, locked rear and traction control in the front.

[David Anderson]

Taipan, I have the factory rear diff lock because if was cheap, but I do like the idea of the ARB's + traction control - that would have to make a Pajero pretty hard to stop..

[Ranger J]

Originally Posted by David Anderson

Taipan, I have the factory rear diff lock because if was cheap, but I do like the idea of the ARB's + traction control - that would have to make a Pajero pretty hard to stop..

You'd be surprised.

I've got the ARB rear locker/front TC combo and I've had a few occasions now where the rear is locked and the front differential is going nuts to get traction to the right wheel. Nevertheless, it gets most places where I want to go, but IMO that locker is worth every cent.

[Pickle]

Traction Control will out perform locker in most cases. Once it gives up the ghost though you better start reaching for that switch....if you have one.
Dave

[4eP]

It's all about getting traction, is it not?

A good traction control system can emulate a locked diff., but a locked diff cannot emulate a good traction control system.

I ask myself this question:
If today is the first day of 4x4 vehicles (ever), would the designers opt for TC or mechanically locked differentials?

Diff locks were designed before electronic control of traction was available.

[Ranger J]

Originally Posted by 4eP

It's all about getting traction, is it not?

A good traction control system can emulate a locked diff., but a locked diff cannot emulate a good traction control system.

I ask myself this question:
If today is the first day of 4x4 vehicles (ever), would the designers opt for TC or mechanically locked differentials?

Diff locks were designed before electronic control of traction was available.

Originally Posted by Pickle

Traction Control will out perform locker in most cases. Once it gives up the ghost though you better start reaching for that switch....if you have one.
Dave

These are big calls fellas!

I still think you can get further with diff locks, than you can with TC. My train of thought is this, on any given differential:

-Diff lock - Best
-Traction Control - Better
-LSD - Good
-Open Differential

Traction control and LSD's are both re-active traction control aids (as opposed to diff locks being proactive). Yes they are fast (in the order of milliseconds) to react, but that can often be the difference between making it through an obstacle or failing to.

As a side note, with TC:
-you get less km's out of brake pads;
-if your working it hard the braking system is likely to overheat;
-your relying on electronics (which has proven to give up the ghost at times) and;
-it just sounds nasty when working!

[David Anderson]

Originally Posted by Ranger J

-Diff lock - Best
-Traction Control - Better
-LSD - Good
-Open Differential

That would have been my thinking as well, but now I'm not so sure and would like to do some more direct comparisons in a few different situations.

As to the noise, the system seems fairly quiet to me ?

(I bet I've lost my hearing since getting the Mickeys)

[bbeasley]

I do not think its a matter of one being better than the other. They are different tools for different jobs. I have a factory locker on the paj and prefer it to TC. My last vehicle had a locker and no TC so i think i am used to it and i do not like the noises TC makes. I can lock the rear and drive up with out the carry on so i do.....still working on trusting TC even though i have seen it do some great things it just makes me nervous.

Cheers,

Brett