Agressive ABS???

[Widge]

OK so I was on the way home from work yesterday, country roads I know quite well - trying to save fuel as I'm broke and I get overtaken by a tosser in a gazzed up blacked out punto Big exhaust and all that, so I speed up to follow him, he's not really going that fast So the overtaking opportunity arises- 3rd gear down to 2nd I overtake and get up to 80ish, come over a hill to be confronted by a junction I don't remember being so soon. Slam on the brakes and to my horror the car does not seem to be stopping quick enough I push the pedal harder and it makes no differance as the ABS has alreaady cut it quick down changes and a bit of revving that I wouldn't usually subject my engine to and I manage to stop at the T junction...just
I have had this problem with the ABS before too, it's great on the motorway and stuff but on country lanes etc I'd rather have it cut in later and get a bit more feel.

So my question is - is the any mod that will allow me to change the cut in point of the ABS? Brian electronics genius where are you? I'd rather not just pull out the ABS fuse cos I do still want it to work when totally needed. Any ideas? And has anyone else had any similar experiences?

[Lordschleife]

OK so I was on the way home from work yesterday, country roads I know quite well - trying to save fuel as I'm broke and I get overtaken by a tosser in a gazzed up blacked out punto Big exhaust and all that, so I speed up to follow him, he's not really going that fast So the overtaking opportunity arises- 3rd gear down to 2nd I overtake and get up to 80ish, come over a hill to be confronted by a junction I don't remember being so soon. Slam on the brakes and to my horror the car does not seem to be stopping quick enough I push the pedal harder and it makes no differance as the ABS has alreaady cut it quick down changes and a bit of revving that I wouldn't usually subject my engine to and I manage to stop at the T junction...just
I have had this problem with the ABS before too, it's great on the motorway and stuff but on country lanes etc I'd rather have it cut in later and get a bit more feel.

So my question is - is the any mod that will allow me to change the cut in point of the ABS? Brian electronics genius where are you? I'd rather not just pull out the ABS fuse cos I do still want it to work when totally needed. Any ideas? And has anyone else had any similar experiences?

Modern ABS can easily out brake any human as it can modulate all 4 wheels independantly at a vey high rate

However the ABS on an e30 is very primative, it modulates at a slow rate and is quite on/off. I much prefer the non ABS of my 318is to the ABS I had on my 325i
But it has to be said in a situation like that you probably couldnt have stopped much quicker yourself anyway as if the ABS cuts in you're stepping over the amount of braking force the tyres can transfer to the road. If you had no ABS and as you said pressed the brakes harder then you would have locked up and slid even further, what you need to do is slightly lift off the brakes then gently apply a bit more pressure again
Try better tyres as a start (what are you running now?)

[Lordschleife]

Oh and dont forget you were just over a crest so your braking potential was probably a little less than normal too

[Dan318-is]

lordschelife is right as usual. and yet agian i agree, i do prefer non ABS.

it sounded fookin scary what happened manb, hope ur ok, glad u nailed a punto tho

On the abs front, are u sure it was ABS messing up and not the rest of the brake system e.g. fluid or brake parts

im not that good on ABS systems but maybe the sensors?

Hope im of some help lol

[astondg]

I have to agree with those comments. The ABS is probably only 2 channel as well (one for front wheels and one for rear wheels) not 4 channel or whatever they have now (one for each wheel). So braking force is limitted to the wheel with the least traction at the front and the same at the back. Even so it will still stop you fairly quickly and unless you are very good at braking (feeling for lockup and modulating the pedal) it would probably stop just as quickly.

Like everyone else said, some good pads, brake fluid, tyres, and maybe discs, would make a big difference to the stopping distance with or without ABS.

Aston

[Brianmoooore]

Pretty sure the ABS is three channel. Backs together, but fronts seperate.
A lot of the roads I drive on are single track and the hedges are frequently damaged by tractors, so that when you meet a grockle speeding down the centre of the road you have to brake with your left wheels on mud with hardly any grip.
If the ABS grouped the two front wheels together, I would get hardly any braking at all.

[Jon_Bmw]

Pretty sure the ABS is three channel. Backs together, but fronts seperate.
A lot of the roads I drive on are single track and the hedges are frequently damaged by tractors, so that when you meet a grockle speeding down the centre of the road you have to brake with your left wheels on mud with hardly any grip.
If the ABS grouped the two front wheels together, I would get hardly any braking at all.

Would have to completly agree with that, 2 channel would be dangerous, you could end up as brian rightly said with no braking force whatsoever.

The abs is better than an M reg cavalier i used to drive, its much quicker at modulating on and off. I personally don't have a problem with it, and think on britsh roads you would be nutter to disengage it. On a track it maybe a different matter were things are more predictable.

[astondg]

Your probably right about that. I was just guessing given the age of the cars but I am sure BMW was ahead of the average cars of the time.

That is a situation where 3 or 4 channel ABS really helps. A driver doing it by themselves would have to lock the wheels on the mud and loose a bit of braking force from them in order to get the most braking from the ones on the bitumen. That might also require some corrective steering work too. Unless of course the driver has 4 brake pedals .

Aston

[Brianmoooore]

I have a non ABS E30 as well that I drive on the same roads, and the technique is to lock the left wheels and do all the braking with the right (but thet tend to be on loose gravel as well).
Cadenz braking is the best technique with non ABS on surfaces like these.

[calder]

i would say the ABS is two channel only - there are only two brake pipes through the ABS pump; one for front, one for rear. The left/right split for the front happens back at the bulkhead near the master cylinder.
Another factor in the ABS/slowing down would be the country roads, possible gravel on surface, mud etc as its getting to harvest time, tractors on the roads and so on - and maybe the weather.
I've also had a few "ABS moments" (not in the bm) when i've braked hard, ABS has cut in and i've realised that i'm a passenger at the mercy of the ABS and the road surface and had to hope that the white line at the junction didn't arrive too soon. At the time, modulating the brake pressure wasn't an option I had in mind.

I've seen some very impessive demonstrations of a driver outbraking ABS by about a car length (not sure how many channels). This was on an airfield so it had a predictable surface and it helps if the driver is an ex-F1 test pilot. For general road use probaly best to stick to ABS for those panic moments and it also allows you to steer.

[astondg]

I have a non ABS E30 as well that I drive on the same roads, and the technique is to lock the left wheels and do all the braking with the right (but thet tend to be on loose gravel as well).
Cadenz braking is the best technique with non ABS on surfaces like these.

Yeah that's what I was meaning. And depending on the situation the locked wheels might cause the car to slide around a bit.

I've seen some very impessive demonstrations of a driver outbraking ABS by about a car length (not sure how many channels). This was on an airfield so it had a predictable surface and it helps if the driver is an ex-F1 test pilot. For general road use probaly best to stick to ABS for those panic moments and it also allows you to steer.

Definately possible, especially on gravel or some other loose surfaces where locking the wheels can be a good thing because it helps to get through the loose top layer and down to a layer with more grip.

Aston

[TheDutch]

I haven't had a chance to play with many new ABS systems, but certainly the old ones were great for keeping you in control of the car, but dire if you actually want to stop. OK they were better than just locking up, but it was easy to stop considerably quicker if you can avoid it cutting in. I'm sure this is definitely true of the E30 system, especially if it has a tendency to come on prematurely then not go off again like Widge seems to suggest.

[calder]

I've seen some very impessive demonstrations of a driver outbraking ABS by about a car length (not sure how many channels). This was on an airfield so it had a predictable surface and it helps if the driver is an ex-F1 test pilot. For general road use probaly best to stick to ABS for those panic moments and it also allows you to steer.

Definately possible, especially on gravel or some other loose surfaces where locking the wheels can be a good thing because it helps to get through the loose top layer and down to a layer with more grip.

Aston

Aston, sorry, the airfield that I meant has a tarmac surface like probably most in the UK; i should have been more specific on surface and I forgot that grass or dirt airfield surfaces are common outside the uk - especially i guess in Oz. I gather that your experience with your race car is on mixed surfaces?
i don't really know about mixed/loose surface but understand what you mean about digging into loose surface to find more grip, this can build up a "bow wave" of loose material to help slow down the car. I believe that this can also work in snow - hence ABS is not much use in snow - but don't try this at home.
On tarmac if you can feel the optimum braking tyre slip angle then a, you're a driving god and b, you can outbrake simple ABS systems as the ABS is set to operate at a tyre slip angle over the optimum and hence is less efficient at braking. Most of us will have seen the ABS skid marks on the road where you get about 4" of skid, 4" with no marks, 4" of skid, 4" of no marks etc so the tyre is skidding around 50% of the time and being alternately over and under the optimum slip angle [technical bit over].
(PS i'm definitely not claiming to be able to do this myself).

[jmc330i]

The abs is better than an M reg cavalier i used to drive, its much quicker at modulating on and off. I personally don't have a problem with it, and think on britsh roads you would be nutter to disengage it. On a track it maybe a different matter were things are more predictable.

I went from a K reg Cav to the BMW and the BMW ABS is a lot better than that was, ok it was Vauxhall

The Vaux ABS did have slow 'on/off' modulation and this made it very harsh and I found it cut in a bit sooner than I would of liked. A friend of mine with a 51 plate Astra also complains that his cuts in too early.
The Cav was the first car I had with ABS, it was so harsh that when it cut in for the first time I stopped cause I thought something had broke - well, it was Vauxhall

I was surprised how quiet and gentle the BMW ABS was when I tried it for the first time. Thankfully Ive only had to use it once properly in anger (loads of steering with the anchors firmly planted), and it worked bloody well, I doubt my 325i would still be here if it didnt

[Widge]

Cheers Guys, it was just a though, there is no way I would disconnect it and the BMW ABS is years better than other cars of the same age.

[astondg]

Aston, sorry, the airfield that I meant has a tarmac surface like probably most in the UK; i should have been more specific on surface and I forgot that grass or dirt airfield surfaces are common outside the uk - especially i guess in Oz. I gather that your experience with your race car is on mixed surfaces?
i don't really know about mixed/loose surface but understand what you mean about digging into loose surface to find more grip, this can build up a "bow wave" of loose material to help slow down the car. I believe that this can also work in snow - hence ABS is not much use in snow - but don't try this at home.
On tarmac if you can feel the optimum braking tyre slip angle then a, you're a driving god and b, you can outbrake simple ABS systems as the ABS is set to operate at a tyre slip angle over the optimum and hence is less efficient at braking. Most of us will have seen the ABS skid marks on the road where you get about 4" of skid, 4" with no marks, 4" of skid, 4" of no marks etc so the tyre is skidding around 50% of the time and being alternately over and under the optimum slip angle [technical bit over].
(PS i'm definitely not claiming to be able to do this myself).

No it is me who should appologise (sp?). I understood you meant a tarmac surface, I was just adding to that by saying that it could also happen (and be even more likely) on loose surfaces. You are right about snow too. I do have a little bit of race experience, on tarmac and gravel/clay/mud like you said, but I doubt I could outbrake even a simple ABS system on a good tarmac surface. I'd like to have a go at that though .

Yes I am in Australia and we do have some dirt and grass airfields here but I live in a major city (capital city of the state I live in) so we do have a more conventional airfield . We even have domestic AND international aiports! And sometimes, at least a couple of times a year, they clear all the Kangaroos and Koalas off it and an aeroplane actually lands on it! The whole city turns out to watch it.


Aston

[jmc330i]

And sometimes, at least a couple of times a year, they clear all the Kangaroos and Koalas off it and an aeroplane actually lands on it! The whole city turns out to watch it.

Yeah, I found ABS to be useless for stopping on snow, but I was able to steer which is what its all about.

A couple years back now in the Cav, driving to the pub one Saturday night on compacted snow. I braked very lightly in a straight line, but just cruised past the turn for the car park with the ABS pumping strong, much to the amusement of my mates I only had to touch the brake pedal and the ABS would cut in.

[Jon_Bmw]

And sometimes, at least a couple of times a year, they clear all the Kangaroos and Koalas off it and an aeroplane actually lands on it! The whole city turns out to watch it.

Yeah, I found ABS to be useless for stopping on snow, but I was able to steer which is what its all about.

A couple years back now in the Cav, driving to the pub one Saturday night on compacted snow. I braked very lightly in a straight line, but just cruised past the turn for the car park with the ABS pumping strong, much to the amusement of my mates I only had to touch the brake pedal and the ABS would cut in.

In the snow abs is quite pointless, doesn't do anything at all.

I know what you mean about the vaux abs thing, when you said you pulled over because you thought you'd broke it. It makes the nastiest crunching noise ever! It sounds Criminal.