13 replies to this topic

[mariner]

As Tony Matthews and other brits here might testify the roads in southern Uk are now full of potholes, not just random ones but whole areas of deep ruts. The hi grip safety coatings are also breaking up.

Now this post isn't to ask for sympathy but to ask if anybody knows how good ABS is at handling serious potholes and long patches of surface break up?

I ask because I came acoss an article from the 1970's at the birth of ABS which suggested it is not very good on broken road surfaces. This seems counter intuitive as it relaeses locked up wheels but I have also seen that on very loose surfaces like snow or gravel ABS might make stopping distances extend and not shorten.

Does anybody have any information or evidence on this question?

[giskard]

As Tony Matthews and other brits here might testify the roads in southern Uk are now full of potholes, not just random ones but whole areas of deep ruts. The hi grip safety coatings are also breaking up.

Now this post isn't to ask for sympathy but to ask if anybody knows how good ABS is at handling serious potholes and long patches of surface break up?

I ask because I came acoss an article from the 1970's at the birth of ABS which suggested it is not very good on broken road surfaces. This seems counter intuitive as it relaeses locked up wheels but I have also seen that on very loose surfaces like snow or gravel ABS might make stopping distances extend and not shorten.

Does anybody have any information or evidence on this question?

Just personal observation, hitting a sharp bump or rut under heavy braking can invoke "ice mode" which drops braking force dramatically. There was one on my daily commute with which I practiced releasing and stepping on the brake again to get it out of ice mode.

[sblick]

ABS systems are very good going from surface to surface and also split mu (left to right friction changes). As stated above if you happen to hit ice mode the abs should react in a couple cycles to a higher mu surface. I use to lock up my fronts over train tracks and then the rears would hit and lock up. By the time my fronts were a couple feet onto high mu (high friction surface) I was at full braking power on the fronts with rears clicking. Once the rears were over I was out of ABS since the ABS sensors noted they weren't needed anymore.
All the first world OEMs have tests for split mu and surface to surface mu changes. These would be snow to pavement, gravel to pavement, ice to pavement and variations there of. There are also bump tests or pothole tests. The hard part is getting the ABS, TC and Stability Control to work seamlessly together when you are driving a car hard on multiple surfaces. That is where the really good engineers separate themselves.

[kikiturbo2]

I get repeated problems on my car with ABS going into "ice mode" when braking heavily on the track, if the brake zones are rough or have small ripples.. I hear several porsche owners having the same issue on the track..

I have experienced similar on the road, again for the same reason.. I just with there was the bloody ABS off button..

[Lee Nicolle]

While never a fan of ABS some systems are far better than others. I have found it works pretty well on rough surfaces, it does make the cars tend to be idiot proof. Though I know I could stop quicker by pure size 9 only, but very carefully!!
This is on a diverse range of vehicles, rear drive, front drive and all wheel drive.
My only experience with ice the ABS seemed to do an ok job. Probably better than me as it was dark and I could not see it, not pleasant at all.It really got my attention!!

[Dipster]

While never a fan of ABS some systems are far better than others. I have found it works pretty well on rough surfaces, it does make the cars tend to be idiot proof. Though I know I could stop quicker by pure size 9 only, but very carefully!!
This is on a diverse range of vehicles, rear drive, front drive and all wheel drive.
My only experience with ice the ABS seemed to do an ok job. Probably better than me as it was dark and I could not see it, not pleasant at all.It really got my attention!!

ABS on a Ford Mondeo I owned some years ago saved me from a possibly awful situation. I was in an industrial area of Warsaw, Poland. It was winter, at night, no street lights working, snowing onto ice. Driving carefully and quite sobre (honest) I suddenly saw a man appear from in front of me, "out of nowhere". With ABS I was able to brake and avoid this (presumaby) drunken idiot. Had I hit him I would have had the nghtmare of local bureaucracy to deal with not to mention the personal upset it would doubtless have caused me.

However I agree with Lee that I really believe that I could normaly out perform ABS, But I have no doubt that it out performed me that night. To get back to the topic the roads of Poland at that time were pretty awful. But I imagine that the layer of ice and snow had left a reasonably smooth surface, so doubt that the ABS had a particularly difficult situation to contend with.

[Tony Matthews]

ABS is for the 99% of drivers who can't brake properly. I don't mind having it on my vehicle if it means a lot of idiots have less chance of driving into me.

Edited to say that Dipster is right, there are times when it can get you out of trouble.

Edited by Tony Matthews, 22 February 2013 - 10:10.

[Ross Stonefeld]

ABS is fine. Most of the time it's engaged in reactive stops and even amongst us expert drivers we may forget to threshold brake in the suddenness of the moment.

[Imperial]

I can confirm that having tested my missus' Citroen C3 on our road (which has become a horrid mix of broken up bits of gravel and slick tarmac) the wheels did indeed lock up while trying to stop on the mixed surface.

My Nissan Xtrail also unhandily locks up on ice.

Not wanting to die in a car accident I don't subscribe to the Nigel Roebuck-esque "ABS is for people who can't drive" BS. I can drive, but it's nice to know backup is there, however....my ABS experiences suggest it's not all it's cracked up to be.

[Imperial]

To get back to the topic the roads of Poland at that time were pretty awful.

I take it you haven't been back recently?

The Xtrail journeys all the way to near the border with Belarus, two times a year usually, and I've long since stopped bothering to pay to get my tracking reset after 100s of kms of smacking into holes in village after village when the motorway/any hope of a decent road ends at Warsaw (which itself remains awful on the dual carriageway on the eastern-side).

In Polands defence, the tarmac does have to put up with +40 degree summers and -10 winters.

[Dipster]

I take it you haven't been back recently?

The Xtrail journeys all the way to near the border with Belarus, two times a year usually, and I've long since stopped bothering to pay to get my tracking reset after 100s of kms of smacking into holes in village after village when the motorway/any hope of a decent road ends at Warsaw (which itself remains awful on the dual carriageway on the eastern-side).

In Polands defence, the tarmac does have to put up with +40 degree summers and -10 winters.

No I have not been back recently. But I got so fed up dealing wih the ravages of poor roads (I tended to work in developing coutries) I ended up with a Land Rover Defender. It takes potholes in its stride. It took crashing down manholes in tropical storms (the covers were nicked and the flooded streets meant you couldn't see the manhole) in its stride too. A slightly more civilised version (I describe mine as a JCB wth seats) and perhaps only 2WD and no transfer box woud be ideal for many people on modern Britain's roads! My one has no ABS of course....

[Lee Nicolle]

No I have not been back recently. But I got so fed up dealing wih the ravages of poor roads (I tended to work in developing coutries) I ended up with a Land Rover Defender. It takes potholes in its stride. It took crashing down manholes in tropical storms (the covers were nicked and the flooded streets meant you couldn't see the manhole) in its stride too. A slightly more civilised version (I describe mine as a JCB wth seats) and perhaps only 2WD and no transfer box woud be ideal for many people on modern Britain's roads! My one has no ABS of course....

For slightly different reasons I own a Landcruiser. Far more civilised. V8 Auto, air cond, Cruise control, ABS brakes. Plus a decent ride and handling. And this one is even Independent front suspension!
While not the ideal bush basher it is Ideal for covering a lot of km in the Aussie bush, ideal for towing a racecar. And very handy in traffic too as you can see over it!
In the country 900km from a refuel, not nearly so good around town though unfortunatly.

[GreenMachine]

.. I just with there was the bloody ABS off button..

Try lifting the handbrake a little, just until the warning light comes on ...

The bill is in the mail.;)

[kikiturbo2]

Try lifting the handbrake a little, just until the warning light comes on ...

The bill is in the mail.;)

well, on my car that would disengage the centre diff lock, so that is no good.. sorry.. .

also, ABS and active diff's ECU share some sensors, so taking out the ABS fuse is no good also.. (although I did that with much success on various other cars.. )

I think a ABS ECU remap looks more and more interesting..