Thread: Bypassing Traction Control

Originally Posted by roverrescue

Just to put the place on the map
See attached
200m climb over 2200m

Interestingly the same 1:10 gradient as the sand hill off 14mile beach at Cape Flattery - but callcup is twice as long
Ouch!

I still think a rear ATB will be your hero


S

The first section seemed reasonably easy, with getting of the beach being the hardest bit. The real climb is on the second leg. The second leg starts just before the 1Km mark, at the 90? bend. This is where everyone get's their run up to tackle the super loose sand on that section. It is also chopped up pretty bad. There is also a limestone outcrop on the left side of the track at the kink, just after the 1.0 Km marker, that the ruts in the track will try to flick you into when you are flying along. But what stops you on this hill is that the sand gets looser the further you go up. There seems to be nothing binding it together, and it's too course to blow away. But that is what makes it a challenge.


I had a look at the Ashcroft ATB, and I can only say I now know what I want for Christmas.....

Thanks for putting me onto them Roverrescue.

I suppose now I need to justify them in my budget..... How long do the Rover diff's last? (I assume that is what is under my Puma 90.) If they normally only last 100K then I only have 12K to go.

Now ya talking!
If it was my money I'd buy a rear and LT230 ATB over rear and front
Or he'll - its Christmas grab all three

Steve

Long timer
Putting an ATB into the rover diffs by a competent installer ensures the mesh of the crown and pinion is good - hopefully lengthening their lifespan
The LT 230 diff on the other hand can be a problem child - replacing it with an ATB is a permanent and good improvement

Steve

Originally Posted by garrycol

Sorry - I read your post in its entirety before responding - if you meant to say something else then you need to explain further - I stand by my comments.

To maintain momentum on steep sand inclines requires you to go at a certain speed, in relation to the condition of the sand.

Where it has been chopped up and cross pitted, so that you are cross axleing (have I invented a new word here???), you are faced with a choice. Go slow and maintain maximum traction, and not be able to get up the hill. Or. Go fast enough that you are effectively skimming the tops of them, maintain speed and get up the hill.
When you are going fast, the wheels that are on the high points aren't spinning (opposite sides front and back). But the other 2 are. So the TC kicks in and applies the brakes to those two wheels. As we continue our slow motion timeline, now the braked wheels become the wheels on the high points, so the other wheels are now spinning. The TC applies the brakes to the other wheels as it releases the pressure on the first wheels. But the brakes haven't released from the first set yet. This process happens again and again, very quickly. Too quickly for the brakes to release from the disks. Effectively, this applies the brakes to all 4 wheels at once, because it happens all to fast for the TC and brakes too respond.

It is a similar process that does it, when your tyre pressures are too high in flat soft sand, and your tyres spin. The cross axleing is measured in mm, but the effect is the same. So there you are. You haven't gone far, and you're not really stuck, but you can smell the hot brakes.

So, when you decide to go fast enough to float over the chopped up sand hill track, you will get some wheel spin. It's inevitable. And as you are going fast and hitting lumps in the track, your tyre pressures need to be higher. And if it's cross pitted, you will get the brakes applying to all 4 wheels at once.
The cross pitted tracks are caused by multi vehicles amplifying the slipping of the first vehicle's wheels, by also slipping it's wheels on the way down each little lump while under power.

Did any of that clear it up? I know I got side tracked a couple of times there, but it's all relevant. I hope. :-)

When I owned a D2 I would always turn off traction control going up Calcup Hill. I was not the only one felt the need to do it in those circumstances either.

I would have thought turning off the TC so there are open diffs would have made it more, not less, likely you would get stuck. It has certainly gotten me out of trouble numerous times.
I'm a big fan. I think the TC plus anti-stall in our 2009 Defender is more effective than the rear auto locker plus open front diff in our previous D1.

Sent from my SM-G900I using AULRO mobile app

Traction control is off but CD still locked. Can be done on D2

Originally Posted by Longtimer

Thanks for this Scarry.
But now I have some questions.

Are you talking about just when he is sand driving? Because that is the only time I would turn mine off.

Just so you understand where I am coming from;
For everything else I was intending on leaving the TC on. In fact, I was intending to leave it on for most sand work too. But, for those chopped up challenges that nobody seems to be able to get up, I thought it might be better turned off. And rather than pull the fuse, I thought it would be better to fit a switch.
Plus, I can always remove the switch if it proves to cause more problems than it's worth.


Though, now that I have seen the data on the Ashcroft ATB.... I think I want 2. :-) And for the price, it would be probably worth it.

Yes sand driving only,two open diffs,centre locked, is nowhere near as capable as with the TC working.

It was repaired after the trip,so didn't have a chance to use it anywhere else.

Anyway,easy to sort out,pull the fuse or whatever,give it a go in the soft stuff and report back