Zinke wrote:

I seem to remember something about going down very steep muddy hills that it can cause some problems too with the ABS. Think LRO picked up on it when the Defender first got ABS/TC.

Pete.

Complete rubbish. It is from a Aussie guy who looses control because of the tires and the way he drives. The link has been used on this forum many times before. Or 'Youtube' 'Defender v Land Cruiser' and it is on there in 2 parts.

It is about the Anti-stall rather than ABS or TC

Glyn

Glynparry25 wrote:

Zinke wrote:

I seem to remember something about going down very steep muddy hills that it can cause some problems too with the ABS. Think LRO picked up on it when the Defender first got ABS/TC.

Pete.

Complete rubbish. It is from a Aussie guy who looses control because of the tires and the way he drives. The link has been used on this forum many times before. Or 'Youtube' 'Defender v Land Cruiser' and it is on there in 2 parts.

It is about the Anti-stall rather than ABS or TC

Glyn

mse wrote:

Zinke wrote:

Works up to 2010MY for sure, think they have changed from wabco to bosch (think its bosch?) for the 2011MY so not had chance to try it out yet on the newer system.

Pete.

You are right Wabco to Bosch at July 2010 for the 2011MY...i have the Wabco; but still not tried it yet (but never had a need)

I was testing ABS on my weekend racer and defender a year ago : performing some tests
stoping on tarmac, grass , mud...

and im sure abs wil cause longer stopping distance´s in general except dry...
Off course after reading a lot about abs in racing and in general , I ditched it from my weekend racer (old 520i)

I will try to explain what I found : sorry for the bad grammar and please feel free to correct me, that´s why there are discussion boards .

Let´s say you are driving on grass at a reasonable speed : and suddenly brake as hard as you can , the abs wile intervene and will not lockup any wheels : it simply doesn't allow the pedal to go any further !

I tried several times to put almost my whole weight on the pedal, it wouldn't move an inch more!
Now you say ; that´s normal that´s abs , you can steer then ... But!

if your tire while cruising is using let´s say 5% of it´s potential grip
and if you brake you will use 95%-100% of the tire´s grip between abs impulses to brake...
Then you will have a remaining 5%-0% for steering ... and also count the laws of physics into that (a moving object always travels straight) and also weight transfer is an important variable (inside wheels lock faster)

Now most newer cars with their ESP are much... much... more aware about some factors : they have Gyroscope´s ,accelerometers,clutch sensor,even a gear sensor nowadays (shift display) and also have a steering wheel position sensor .

those new cars can adjust their braking really accurately ,based on the inputs of the steering wheel sensor , wheel sensors, and brake,clutch and accelerator pedal.

this combined with the gyroscope , and accelerometers: The ECU know´s which direction the car is moving .
and if the direction doesn't match the steering wheel senor : the car will try to brake individual wheels and steer the vehicle :

example:
If you brake really hard and steer : the ESP ECU knows you want to go that way and brake. it will try to figure out the needed grip to steer lets say 30% , and the left over grip to brake 70%

now we all now that a defender does not have all those gizmo´s and thank god who knows what will hapen!

A defender´s abs is Analogue ... it always wants to stop as quickly as possible and it try´s to do that realy hard .
It works in dry in a straight line : and u can maneuver a bit
but in the wet... please . there´s almost no steering...

now the biggest drawback for me with almost all ABS systems is :
if you are braking hard ... and 1 wheel hits a sheet of ice or mud even those white roadmarkings ,track curbs and the other 3 wheels have 100% grip.
The abs will push up your pedal and make sure the car is going to go straight and does not deviate . because of 1 wheel having less grip

also the rear left will most likely hit the patch!

And like I earlier said the ABS pushes the pedal back... ! So when you got full grip again , it takes some time the push the pedal back down... (maybe 0,1sec delay)

basic math´s:

So there u have 1000N of stopping grip per on the front wheels 500N on the backwheels
3000max total on perfect dry conditions with non locking wheels

Lets say the left front hits a slippery patch(with 50% grip) and decreases to : 500N
right front also goes to 500N to keep the car straight 2x = 1000N
and the two rears go to 250 each (logic) x2 =500N
this is aproxx 1500N

let´s sum it up : 3000N = with no abs intervention
ABS you have 1500N and you drive straight but you have an intervention of +-0,5 seconds

and let´s say the driver feathers the brake try to not lock the wheels (and feels when they lock)
non ABS you have 2100N and possible risk of oversteer .

that´s +-600N extra 28% stopping power

now you can do the math for a stop from 25m/s 90km/h
dry road, perfect grip, no locking : 55m
dry road, perfect grip, no locking +1sec l : 80m
dry road, perfect grip, good driver so you lose +-15% : +1sec : 92m
Abs dry road, perfect grip : 5% loss of grip abs locking pulse (you wont notice the loss) +1sec : 84m
patch 1,0sec 78% no abs good and a good driver : = 85,55m
patch 1,1sec 50% with abs +1sec : = 93.5m

these calculations are probably not perfect...
if I made a mistake feel free to correct , I am not studying math

so if my basic math´s are correct :
even if there´s no black ice or ice , ABS can cause longer braking distance´s

And about ABS on ice :
Ice has at leas some friction : if you lock your wheels wouldn´t that create more friction and heat , so the can cut in the ice? or is the friction too low?

greetz ! Discovery 4 SDV6 Landmark
F31 320dA Msport xDrive
LR Defender 90SW TD4 Stornoway grey
320d E46
E70 X5 3.0d Sold!
FFRR TD6 - Sold

Glynparry25 wrote:

First time I have heared of anything like that. Sounds like something faulty..... otherwise it would have ended up in a recall.

*Edit*.... when the wheels would have started turning when the abs released it the sensors on the hub would have detected movement again and re-applied the brakes.

Talking about recalls...... did you know that 2 years ago it was recognised that the large glass on the roof on the Ford Galaxy was prone to comming free and there were incidents of it either coming off whilst driving at speed or falling into the vehicle..... they kept that one quiet.

Glyn

Zinke wrote:

Not saying it right, just what ive read. Most likely driver error but trying to blame land rover.

Pete.

Yeah, the whole.... I did everything right but the vehicle just crashed into the hedge that jamp out in front of me

Glyn

Glynparry25 wrote:

Alexke,

Yes and no. What you have to remember is that when a tyre locks up you aren't getting the potential out of it therefore less friction, so look at it this way:

A. You are braking to hard already if have locked up/ ABS is kicking in (Bad driving)

B. We will say on a scale from 1-10 the friction of a tyre 1 being none, 10 being loads of friction. A tyre that is locked/ skidding will have a friction of say 3 where normally it will be 7.

So a locked up tyre will take longer to stop than one that has contact?

ABS isn't 100%.0%.100%.0%..... it works its way up and down so friction will be more of a staged 7.5.3.5.7.5.3.5. which means it will have an average of say 5.

I have tried to keep it simple (my brain is hurting today).

Abs dry road, perfect grip : 5% loss of grip abs locking pulse (you wont notice the loss) +1sec

As for Ice, yes you have a valid point.... but only if it is just single wheels rather than complete ice. Not so much for water as the whole surface is normally wet.

Glyn

Alexke wrote:

Abs dry road, perfect grip : 5% loss of grip from abs locking pulse (you wont notice the loss) +1sec

Glynparry25 wrote:

As for Ice, yes you have a valid point.... but only if it is just single wheels rather than complete ice. Not so much for water as the whole surface is normally wet.

I find this fascinating :if a wheel locks up on a wet road : the friction of rubbing a locked tire = massive heat road underneath tire heats up and give´s more grip.
And the friction heat will make the rubber more sticky and then shortining stopping distance
but the boiling of H²O underneath the tire can build up and expand , therefore reducing friction
just some food for tought!  Discovery 4 SDV6 Landmark
F31 320dA Msport xDrive
LR Defender 90SW TD4 Stornoway grey
320d E46
E70 X5 3.0d Sold!
FFRR TD6 - Sold

Alexke wrote:

I find this fascinating :if a wheel locks up on a wet road : the friction of rubbing a locked tire = massive heat road underneath tire heats up and give´s more grip.
And the friction heat will make the rubber more sticky and then shortining stopping distance
but the boiling of H²O underneath the tire can build up and expand , therefore reducing friction
just some food for tought!

To be honest I don't think the Heating up/ cooling down would make enough of a difference unless you were doing considerable speed... also remember that the tyre is heating up but the road, and the rain is cooling..

All depends on tyre compounds etc.. Cheap tyre will not produce much heat as the rubber is so hard and it will 'slide' along the surface where if you had a set of Yokohama or Toyo R888 then you will have loads of friction/ heat and the need to go back to the tyre shop to buy a new set.

Basic moral of the story is to think about the way you drive..... ABS ISN'T a form of breaking and more of a safety feature that kicks in to help you out when all else has gone to Sh!t.

Just a quick reminder to all the folks out there who have done the UK driving test.... what is the first thing you are supposed to do if you lock the brakes on a car (dunno if they teach the same in other countries)?

A- push the pedal through the floor and close your eyes and pray.
B- release the brake and re-apply a force so that the vehicle doesn't skid.


What is the rule with driving tests now... when I did it you had to do the good old emergency stop where you had to come to a controlled stop as short as possible without skidding or if you did skid you had to do the off and on tecnique as above....... what if the car has ABS... as the testee could just jump on the brakes and let the ABS control it (or is ABS not considered as under control?).
Glyn

Quote:

Complete rubbish. It is from a Aussie guy who looses control because of the tires and the way he drives. The link has been used on this forum many times before. Or 'Youtube' 'Defender v Land Cruiser' and it is on there in 2 parts.

It is about the Anti-stall rather than ABS or TC

Glyn

Seth Afrikan I believe, not an Aussie.

Cheers
KarlB

KarlB wrote:

Seth Afrikan I believe, not an Aussie.
Cheers
KarlB

Yes you are right. I stand corrected. I keep thinking Aussie because my Bro is as good as one now and looks like I will be looking down that route in the near future.

Glyn

mse wrote:

First of all lets remember what ABS is and does.

ABS is a driver aid that maintains the maximum controllable traction to the wheels to enable proper vehicle control.

Land Rover have been putting ABS in cars long before any manufacture - you will recall its in the Range Rover Classic - they spent a lot of money working out a system that wouldnt screw up off road...some manufactures still have sussed that (properly).

There are some occasions in some setups where you will, by skidding, probably stop shorter than an abs car...but ignoring you are out of control, you wont be able to control the car

in the majority of situations, ABS will ensure you retain control and stop in the fastest time possible.

it´s true.. less drama with ABS in the end ,: but it wont save you

i had 1 senor replaced...

i am gonna try to push my pedal 10 times tomorrow : but do i have to do this in short pulses or long pulses?

grtz Discovery 4 SDV6 Landmark
F31 320dA Msport xDrive
LR Defender 90SW TD4 Stornoway grey
320d E46
E70 X5 3.0d Sold!
FFRR TD6 - Sold