Traction control

Quote:

---

Originally Posted by rovercare

If you play on more difficult terrain, it becomes an issue, may not where you take your vehicles, but that's not necessarily the same as others

---

Out of interest which model LR's have you experienced this behaviour with?

I'm curious because in 1993 WABCO was granted a patent on logic for an all-terrain mode of ABS operation which allows more wheel slip to occur. The description of the patent makes note of the wedge of built up material in front of the locked wheel "causing substantial braking". The invention described in the patent attempts to balance the retention of steering control derived from abs while maximising braking forces on soft and slippery surfaces. The all-terrain mode allows the brakes to lock for short periods.

The technical material for the Wabco Type-D braking system makes mention of the availability of this optional all-terrain mode. While I don't have any hard evidence to support the claim I suspect that LR have used either low range or locked CDL to trigger all-terrain abs operation in vehicles equipped with derivatives of the Type-D system.

If I am correct then the loose surface braking behaviour of post 1998 Defenders, post-1999 P38a's, pre-2001 Freelanders, and Discovery 2's will be quite different in low range|locked cdl operation to earlier vehicles.

I've noticed that Disco 1 and early P38a drivers tend to be the most vociferous opponents of ABS and I wonder if this is one of the reasons?

cheers
Paul

Not that too many of us in this section gets to use it, but that is one of Terrain Response's functions...

I've personally witnessed a D4 on trials with a full payload and max trailer weight stop perfectly safely on a skid pan using all it's electronic trickery. The test was specially aimed at European ice conditions, but gravel would be a breeze in comparison to that.

Fair enough that the Defenders TC is significantly simplified in comparison, but the MY12's system is again a major leap on the MY10's for example.

As I said my previous post was fairly speculative, and having found a "prior art" description in a later WABCO patent I'm not sure that LR have implemented the off-road feature.

It will be easy enough to confirm however. Below 25mph/40kph off-road mode should selectively lock brakes to enhance stopping power, and below 10mph/16kph it should be possible to lock the brakes without any ABS intervention.

Quote:

---

Originally Posted by OffTrack

Out of interest which model LR's have you experienced this behaviour with?

I'm curious because in 1993 WABCO was granted a patent on logic for an all-terrain mode of ABS operation which allows more wheel slip to occur. The description of the patent makes note of the wedge of built up material in front of the locked wheel "causing substantial braking". The invention described in the patent attempts to balance the retention of steering control derived from abs while maximising braking forces on soft and slippery surfaces. The all-terrain mode allows the brakes to lock for short periods.

The technical material for the Wabco Type-D braking system makes mention of the availability of this optional all-terrain mode. While I don't have any hard evidence to support the claim I suspect that LR have used either low range or locked CDL to trigger all-terrain abs operation in vehicles equipped with derivatives of the Type-D system.

If I am correct then the loose surface braking behaviour of post 1998 Defenders, post-1999 P38a's, pre-2001 Freelanders, and Discovery 2's will be quite different in low range|locked cdl operation to earlier vehicles.

I've noticed that Disco 1 and early P38a drivers tend to be the most vociferous opponents of ABS and I wonder if this is one of the reasons?

cheers
Paul

---

Predominantly d2 and early p38s

Quote:

---

Originally Posted by OffTrack

As I said my previous post was fairly speculative, and having found a "prior art" description in a later WABCO patent I'm not sure that LR have implemented the off-road feature.

It will be easy enough to confirm however. Below 25mph/40kph off-road mode should selectively lock brakes to enhance stopping power, and below 10mph/16kph it should be possible to lock the brakes without any ABS intervention.

---

You've got to get below 16kph though:D

I haven't played with later stuff in the bush, I'll be disabling the abs in my own p38 for bush work

Quote:

---

Originally Posted by rovercare

You've got to get below 16kph though:D

I haven't played with later stuff in the bush, I'll be disabling the abs in my own p38 for bush work

---

Below 40kph the wabco off-road/all-terrain mode uses a "deep-cycle" mode that allows the wheels to build up a "wedge" before unlocking to regain steering control. The big question is IF it is implemented by LR on Type-D abs systems :confused: Just need to find a quiet gravel road to play on - which is easier said than done when you live 5km from the GPO. :(


I've attached a chart from the patent showing the progression from normal abs, to deep-cycle, to fully locked.

Attachment 46129

Once the wheel are fully locked they'll slide regardless of abs.

cheers
Paul

Quote:

---

Originally Posted by rovercare

If you play on more difficult terrain, it becomes an issue, may not where you take your vehicles, but that's not necessarily the same as others

---

No issues on any terrain if you are driving sensibly.

I dont have an issue with Abs, I have never had a vehicle with it.
My decision to buy a Defender rather than use my Disco is because it is a V8, 3.5, cant sleep in it, cant carry enough fuel for extended long trips unless overweight and besides, I love it and nowadays I would not want to risk causing it any pain.
My decision to go without the ABS TC option is not based on their ability question but purely financial, I dont think I need it. I think for what I plan to use it for, the diff lock and winch is a better option. I want to revisit the Canning, Madison, pop over to the geographical Simpson centre and check out the Gunbarrel. I also like to bush bash, I intend some of that in Lenny country. In the eighties I bush bashed around the Lake Amadeas region for a few weeks, came in from the north. Always wanted to go back for another look.
I travel on my own not in convoy ( but in time if anyone wants to tagalong on a trip, fine ) so a new reliable truck with the right capability so as not to be a burden on others for rescue, needs some thought. That's why I ask questions and appreciate answers.

I rather like the idea of putting in D1 axles, front and rear ( not mine )
Fitted with Ashcroft lockers and HD stuff. I didn't know they would fit.
I will talk to Graeme at LandRover Spares as he would know about such things.
Nuh, must be new, you have solved the problem re: service so I will take pot luck with warranty. Dont think they would want to know anyway with the conversions that I would make !!!

Thanks.

Robert.

Quote:

---

Originally Posted by Drover

Bailey Morris link provided -

http://www.baileymorris.co.uk/4x4.asp

I ordered mine, arrived 6 days latter, about $650 to the door.

These are a very nice piece of kit
.

---

I forgot to mention.
Thanks Drover.

Robert.

PS: I will be fitting that style of bullbar also and winch with plasma.

Quote:

---

Originally Posted by garrycol

Please explain what??? How ABS works.
.................................................. ......

---

No, your statement that ............'with decent tyres (ABS) is not such an issue when braking offroad'.


Locking wheel(s) on a firm surface increases braking distance (as traction is reduced), ABS compensates for this by releasing and re-applying the brakes to a point before traction is lost thus improving braking efficiency and vehicle control.
In a situation where there is less traction available (loose surfaces) wheel lock up is more prevalent when braking which leads to longer braking distances. In this situation the build up of material in front of the wheels becomes the major factor in slowing down. The wheel may be locked up and skiding but the vehicle is slowing because of this 'wall' in front of the tyre(s). ABS in releasing and re applying the brakes causes the vehicle to drive over the wall thereby reducing braking efficiency. This effect is very noticable when towing a trailer on a typical outback loose dirt/gravel surface. The reason ABS is ineffective on loose surfaces is because it 'assumes' traction is the main contributor in slowing the vehicle.
Whilst tread choice effects traction on firm surfaces it becomes less relevant as traction decreases on loose surfaces.
When you're braking heavily on a ball bearing surface and being slowed by your 'bow wave' tread type doesn't matter as much. Whether you've got HT's, AT's or MT's isn't as important as traction is not the main player in slowing down.
There could be an argument that skinny tyres could give more effective braking (than wider tyres) as they may more easily cut through the loose layer to an underlying firm surface therby increasing traction. eg. My old SII with its factory 6.00 X 16 pizza cutters was suprisingly good in mud as its really skinny wheels readily cut through mud to the underlying hard surface providing traction.
Re the Wabco system, it certainly is not on SWMBO's 2004 D2a but may be fitted to something like the RRS. I don't know. What I do know is that ABS can be a very dangerous, even potentially lethal on loose surfaces regardless of what tyres you've got.

Deano:)