ECU down of the rear seats???

[S2central.net]

I know that one - bit more elaborate than it needs to be, but yes it works if you do the translation from UrS4 to S2.

Had a quick look at S2 schematics - sure enough Fuse 31 kills the ABS, but it also supplies juice to the rear diff-lock controller (RDC)so that would also be disabled with the fuse out - not ideal in all situations.

The RDC disables ABS of course so some simple switching could also fool the ABS into being turned off whilst the rear-diff is open.

Another switch could override the speed-sensing function on the RDC for anyone wanting some locked diff fun above 25kph on a snowy day in Tesco's carpark !

So many switches, so little space - LOL

[Jas11n]

To be honest, I've used it once since fitting it. I switched jobs not long after doing it and the rather mahoosive steep bank I had to descend wasn't on my work route any more. ABS and that bank = scary times in winter.

[S2central.net]

Ahh there you go - a switch that pulls pin 13 on the later ABS controller (ie no ABS switch on the dashboard) to ground will disable it. This emulates the signal from the switch inside the diff housing when its locked... regardless of whether that is true or not.

The switch in the difflock is operated by the difflock mechanism which is actuated by vacuum when the difflock switch is operated... The RDC directs vacuum to a push/pull mechanism to lock/unlock the reardiff... In the factory config, the RDC only allows the diff to be locked at speeds under 25kph... A switch onto the blue/white wire (pin 1 ) on the RDC would disable that if you wish.

[aelred]

Believe it or not you stop quicker without ABS, even on slippery conditions.
ABS was designed for the lesser driver like OAPs, ladies and inexperienced drivers.
A good driver should not need it.

[aelred]

Snow

I always turn mine off in the snow too. Sooooo entertaining

The UR Quattro had the facility of an ABS switch. The owners manual recommended for the ABS to be off in snow conditions as the build up of snow in front of the tyres infact helps braking.
At the end of the day if you got no grip nothing will help.

[stiglet]

Tis true no ABS in snow will stop quicker as the snow builds up, but it's definately quicker stopping with the ABS in the dry and the wet. Main reason being that you can't control the front and rear wheels (plus individual front wheels) with one pedal. Maybe true with the primitive stuff in the Audis, but more modern stuff; definately not

[aelred]

Well I am speaking from personal experience doing tests in wet condition with and without ABS and the results were always the same. With no ABS the stopping distances were always shorter. This was also observed by me with different drivers and results always the same.
This was observed by others and they could hardly believe it as most people believe that ABS is the savior in slippery conditions.
This test were done in a straight line, no test was done on bends, but this is a different story as ABS will greatly help breaking in a bend without fear of loosing the car in the edge. Having said that you can replicate the ABS action yourself. I personaly like to be in control of the car and have a feel for what it is happening, so for me ABS is a very low priority and I do not miss it at all if I dont have it. I am sure others feel safer with it.

[ifa]

Without ABS braking distances are shorter on all circumstances.

[stiglet]

I can see this turning into a pistonheads style thread

In a straight line, on a perfect road with no grease patches, surface variations, etc etc then maybe you could manage to slow down quicker without the ABS interfering. However, in a real life situation where the friction coefficient of every wheel is changing constantly and you have to deal with varying weight transfer and loading conditions, i'll be suprised if you could hold all 4 wheels on the cusp of locking each and every time, especially when without the use of ABS the braking distribution to each wheel is set and will not adapt (I know this is partly EBD but still the same principle).

Like i said, i don't know how good the 15 year old ABS system is on the S2's (can't say i've ever really tested mine) but i can think of more times where the ABS has saved my *** than interffered.

That's my opinion anyway

[Rocco]

Without ABS braking distances are shorter on all circumstances.

and this is just why the 3b are better than the Aby,aa,adu....


aniway the ABS on "usually" its more "safer" true??? its a very very good thing for the girls at steering wheels..... ,no control,no feel nothing never¡¡¡

[ifa]

Abs does not set braking power individually on each wheel.

Example: if your drivers side wheels are on ice and passengers side wheels on dry asphalt. When braking ABS sets braking power on all wheels like they are on ice.

When driving on icy conditions braking distance can be over 10 meters longer with ABS lets say about 40-50km/h speed on start of braking.

[gedu]

ABS has in it's program a "maximum" deceleration figure, that will dictate how fast it allows wheels to slow down. That figure is chosen purely by manufacturer, with regard to different tires and so on. It's always a compromise. In S2/4/6 ABS is infact 3 channel, so it can operate front wheels independently but rear axle is with one brake circuit, so rear axle will be braking as hard, as the least grippy one.

When "original" DTM was up and running they had ABS in cars... made for some interesting maneuvers in late stages of race, as there was rubber all over the track. If you wandered from race line you had basically no brakes

[S2central.net]

This is really a moot argument... The reason ABS exists is a fundamental safety thing - to allow a driver to steer in an emergency where there is a very high chance of locked front wheels from extreme braking... Inexperienced drivers will not feel the onset of brakes locking and even experienced drivers will make mistakes in an emergency situation.

I have invoked the ABS in a couple of real-world sitautions with people pulling out in front of me - in both cases I found myself wanting to relax the brake pedal to prevent lockup at pretty much the time when I could feel the ABS modulating the pedal...

In test situation I suspect that experienced drivers could out-brake the ABS on our cars - as it must have some margin built in - but in a real-world emergency - especially in the wet - where you need to steer round a hazard after/during hard braking then I think its a task better performed by an ABS computer that can modulate the brake pedal much better than a mere mortal !

[stiglet]

This thread has gone so far from it's original point i think it would be wise to start another thread on the effectiveness of ABS.

Abs does not set braking power individually on each wheel.

Example: if your drivers side wheels are on ice and passengers side wheels on dry asphalt. When braking ABS sets braking power on all wheels like they are on ice.

When driving on icy conditions braking distance can be over 10 meters longer with ABS lets say about 40-50km/h speed on start of braking.

I know the phenomenon you're refering to, it prevents drivers from being catapulted into oncoming traffic. On modern ABS systems it balances the two sides of the vehicle at first then gradualy increases the braking force on the side with most grip giving the driver more time to react with counter-steer. However, it doesn't simply put all 4 wheels at the same rate. Because the car is retarding slower, the balance and weight transfer of the vehicle changes to regular braking in dry, therefore changing the force of both front wheels to prevent them from locking up.

This is a pretty extreme case and i reckon you are actually right, an experienced driver could probably retain a shorter distance with quicker reactions to to steering.

However, if ABS is only for grannies and idiots, then why was it used (very effectively) then banned in F1? The drivers probably could do better without, but not for hours at a time mistake free.

[stiglet]

Sorry Paul i didn't see your reply until after i posted!