Improving the ABS

[suzie650]

Hi there!
I've got some kind of an issue with the abs on my car... As quite often noticed by e30 drivers, it kicks in too early.
This will soon be worse, as I will be uprating to a 300mm kit (540 caliper) und bigger tyres -> could brake even harder, which the abs won't let you do due to its programming.

On the other side, this car is not used on the track only, and the abs is a very important safety factor, even for good drivers, which I'm probably not anyway. Actually, with the right set up, an abs is even helpful on the track as I don't know any racing driver who's able to vary the pressure between the two front wheels. -> I'd like to keep it.

From there comes the idea: Is it possible to improve the ABS? Remapping it/changing it?

Do you know of anybody who had a play with the standard ecu chip?

Otherwise, if I've done my homework correctly, the group N E30 M3's were fitted with a specific teves ABS unit and a "group N" chip.
Has anybody got more info about the teves unit?
Does anybody know who could source/copy the group N ABS ECU chip, as these are apparently nla from BMW?

Or otherwise, is it possible to install a later setup (e36/z3/...?/non-bmw?) without going through the hassle of changing all the ABS hubs and sensors? (I know for sure that e36 m3 had a specific group N mapping of their abs ecu, but never saw one myself, and don't know anything about the setup)
The added bonus would be the upgrade onto a 4 way abs. But most of them come with traction control built-in, which goes *** if not connected to an engine ECU.

Any information would be greatly appreciated!
cheers
Seb

And sorry for the long boring write-up...

[suzie650]

I know it's long. Sorry. But does somebody have some (even partial) information?

[blitz877]

get rid of the abs i say, i dont have it and dont need it

[Brianmoooore]

I can point you towards some wiring diagrams: http://www.autolib.diakom.ru/CARS2/

[murran]

if your a good observant driver, how is abs helpful.......... at all?

[Brianmoooore]

if your a good observant driver, how is abs helpful.......... at all?

When you are forced to brake in a corner, or when one front wheel is on a less grippy surface than the other.

[murran]

if your a good observant driver, how is abs helpful.......... at all?

When you are forced to brake in a corner, or when one front wheel is on a less grippy surface than the other.

my question repeated. drive according to your person skill level, the conditions, and the road ahead.
full stop.
dumb people relying on these driver aids to replace their skill (lack of) is what causes so many modern car accident........

[Jon_Bmw]

Murran, everytime you drive you rely on people around you not to do something stupid.

I'll give you an example: You are driving along a major road and there is a car in a minor road indicating to come out. You spot it, note it, and reduce your speed from30mph down to 25mph. If for some strange reason the car pulls out when you are 5 meters away i'd rather have the ABS. Doesn't matter how cautious and good a driver you are, if someone else wants to crash into you, they will. Safety aids reduce the level of pain experienced by the victims.

As for the thread, on track I just don't see the point of ABS I'm afraid. Conditions are constant, cars are only going one way...etc etc.

[Brianmoooore]

drive according to your person skill level, the conditions, and the road ahead.

I do, and have not had an 'at fault' accident in 35 years.
Unfortunately there are other road users around, and some of them don't. ABS helps me avoid them (and them, me!)

[murran]

Murran, everytime you drive you rely on people around you not to do something stupid.

when you start relying on other people not to crash into you, thats when they do!
on todays roads youve got to look at and study the manners of every car your approching or thats coming near you, cus 90% of people on the road havent a clue. never assume anything!
i dont know anyone around my age (27) with an accident free 7 years behind them and its cus i dont trust anyone on the road to do what i expect them to do.

[ShakeyC]

Do you think your locking the wheels when braking? If so there is mechanical fault and going to bigger brakes and tyres will only increase UNLESS there is a fault/binding calipers then issue be fixed once replaced. Not too sure how BMW do the ABS but if one wheel spins faster than another triggers ABS under braking (front to back or left to right ratio wheel speed difference) that tells me somethings needs attention first.

[Cha_Maan]

drive according to your person skill level, the conditions, and the road ahead.

Where's the fun in that?

Unless you have a crystal ball you'll get into an accident sooner or later. Adjusting your driving style to accommodate every eventuality means either you don't ever get into your car or you drive at 5mph everywhere in a state of constant paranoia.

You don't have ABS do you.

[Morat]

Everyone crashes, eventually.
ABS can help on surfaces with poor and/or uneven grip. WHEN you crash, you may not have time to apply the perfectly modulated cadence braking that you've perfected on a track. You might just be too busy trying to identify and steer the only line that will save your life.
You WILL crash one day, and the option to just slam the brakes to the floor and concentrate on steering MIGHT save your life.

There are three places for cars without ABS. The forests, the racetrack and the scrapyard.

[Omi]

This has turned into an ABS or Non-ABS thread, can we get back on-topic, as I find this very interesting. About to M52 and my brakes aren't great, so very curious.

[Cha_Maan]

This has turned into an ABS or Non-ABS thread, can we get back on-topic, as I find this very interesting. About to M52 and my brakes aren't great, so very curious.

Agreed - and apologies.

There's a thread on here that mentioned the special race ABS set-up they used and I'm sure it's programable as it would have to have been for set-up on various tracks / drivers etc.

Problem is, that set-up was very very expensive.

And if you could get it, how would you tweak it as surely all the computers to do that work would be proprietary?

[Cha_Maan]

As for who supplied the shells and engines - BMW Motorsport. In 1989 a car kit (they were not supplied as fully built up cars from BMW) cost around £150'000. BMW M'sport even developed their own racing ABS system.
They pulled out of DTM at the right time just as costs were going mental (Formula 1 budgets).

[Turbo-Brown]

My understanding is that the chip used in things like MegaSquirt was originally developed by Motorolla (or someone like them) for use in ABS systems, which presumably means it's re-mappable just like Megasquirt is.

Re the great ABS debate, it's all well and good to say that every accident is avoidable and that cadence braking is just as effective as ABS etc. etc. but in that panic situation when you're sliding towards a child or something you're fairly unlikely to be letting off the brakes unless you've had LOTS of practice at cadence braking!

[suzie650]

Right... effectively gone a bit off topic.
Thanks to all for the input. I found the topic about official M3 racers. Thanks!

Effectively, on track the abs is not a must. But especially in wet conditions, if something stupid happens and you have to brake mid corner, you're happy to have it. Who can honestly say that they will always react in the correct way when in an emergency situation? I certainly can't. And if you're good enough to not need one, a correctly set-up abs shouldn't kick in.
It was however interesting to talk to a rallye specialist (worked for Tony Pond and Prodrive...) who said that on tarmac, they would run abs when ever allowed by the regs. (They obviously ditched it on loose surface.)

I found the latest racing abs from Bosch (M4)... 4000Euro. Waaay out of my price range!

Which means that the cheapest solution might be retrofitting a later abs. Seing the number of people fitting bits of e36 to their cars (5 stud conversion), are the e36 ABS triggers the same? Or does anybody have experience with other systems?
Edit: Turbo-Brown's answer arrived while I was writing this. Do you or anybody know of somebody who had a play with the mapping of an abs?

[Cha_Maan]

E36 ABS retro-fit is a good idea. I can't see why it would be an issue.

Unless the E36 braking system is somehow also governed not just by it's own ECU/sensors but also affected by input from the engine ECU?

[Brianmoooore]

The more modern the car, the more the various electronic modules talk to each other! All sorts of weird (and largely totaly unnecessary) interconnections on modern cars!

[suzie650]

I know for sure that all later versions with the asc traction control are connected to the engine ecu, and therefore best avoided. - Unless somebody knows what input to feed to the abs ecu to "keep him happy" without connection to an engine ecu?
Cheers
Seb

[Cha_Maan]

The more modern the car, the more the various electronic modules talk to each other! All sorts of weird (and largely totaly unnecessary) interconnections on modern cars!

Very true. Modern system also cut revs via the engine ECU so maybe the E36 was the last system viable before it got really complicated.

BMW (maybe from the E46 onward) also integrated all there wiring into shared looms - a sort of 'Serial Bus' system to save weight and complexity - but ruin home mechanics.

Perhaps a different manufacturer? They're all made by Bosch, Siemens and the like anyway.

The massive tank E-Class Mercedes-Benz (W124?) of the 90's uses the same ABS Hydro unit as E30's for example.

I guess it would be great to find a re-mapper type outfit for ABS. I've never called on my ABS but I know that the E30 system isn't held in high regard - how come?

[suzie650]

Modern system also cut revs via the engine ECU so maybe the E36 was the last system viable before it got really complicated.

Actually, on the e34 540, the throttle was not fly-by-wire but they had asc... You can cut the injection, but without reducing the air intake, you might get into detonation. Guess how they cut the revs?


Yep! A second throttle body further up in the intake!

I know that the E30 system isn't held in high regard - how come?

E30 system is mapped for safe road use, and therefore hardly allow wheel slip on the standard setup. Put better tyres on and the available grip is effectively changed, but not in the abs map. (not adaptive) Therefore, you can't take advantage of your better tyres/bigger brakes. That's why the complaint of an abs "kicking in early"

[Cha_Maan]

Well it only works on braking. I think traction control is what kills the real fun - something we don't have to worry about!

[BadgerSi]

Seb rip it all out like I did

[suzie650]

Seb rip it all out like I did

Simon and Julian, the "just f*** ditch it" squad! I'm not building a track slag! Although not doing a couple laps would be rude, seing where we are

Thing is, if I can't do anything with it, I'd rather put a switch to be able to disconnect it rather than throwing it away. What does it weigh anyway? Not a lot... And probably makes the piping easier as well.

And when I have to get it road legal (which ain't gonna be fun anyway), they will not like an abs car to run without it... Don't even compare it to an english MOT, the swiss procedure and regulations are much more annoying

[BadgerSi]

I might rip it out while you aint looking on thursday!

[Jon_Bmw]

The ABS relay would act like a switch. Remove it and its disabled.

[suzie650]

NOOOOO!
If you do that, make sure that you don't park in front of the green 2 ton scrapyard, or I might "release by mistake" the handbrake Then you would know for sure where your boot is leaking from
back on topic, now...

[Turbo-Brown]

Would it be possible to crudely modify the system by having the trigger points on the hub re-distributed?

You'd have to have them machined off I guess and then have an E36-style replacement made which you could just weld on.

If you had less triggers, the system would think you're going slower and as such that your deceleration rate was lower than it is.

I believe I read somewhere that the M3 had a higher threshold on it's ABS, would it be possible to swap ABS ECUs over?

[suzie650]

Would it be possible to crudely modify the system by having the trigger points on the hub re-distributed?

You'd have to have them machined off I guess and then have an E36-style replacement made which you could just weld on.

If you had less triggers, the system would think you're going slower and as such that your deceleration rate was lower than it is.

I believe I read somewhere that the M3 had a higher threshold on it's ABS, would it be possible to swap ABS ECUs over?

I think that with less triggers, the abs would think you go slower, but the difference in speed within a given time (deceleration of the wheel) would stay the same...
So e36 triggers are different? Are the sensors the same?

Good idea with the M3 ecu. I'll have a look into that!

[Turbo-Brown]

Think of it this way, if you're traveling at 60m/s and stop in 10s, you have decelerated at a rate of 6m/s^2 (I think )

If you were traveling at 30m/s and stop in 10s you've decelerated at a rate of 3m/s^2.

If the threshold for ABS was say 4m/s^2, then halving the number of trigger points would stop the ABS triggering.

Think the only difference between the E30 and E36 trigger wheels is that the E36 ones are cheaper to make as they're just stamped out of sheet steel and then welded on, rather than the machined E30 versions.

I think the E36 ones are ever so slightly larger in diameter too which makes them foul the E30 sensor.

[suzie650]

That's totally right. The deceleration obviously stays the same for us, but not for the abs ecu, which is the point of the possible modification

Realoem says that the abs is the same across the e30 range. M3 included

[Turbo-Brown]

Wonder if anyone has an M3 front hub kicking about which they could count the number of triggers on?

Got a standard car's hub at home to count too, be interesting to see if that's just what BMW did; reduce the number of triggers......SURELY not?!

[murran]

so what exactly are you trying to change about the abs system? the % of slip the wheels are allowed to have under braking before the abs cuts in and takes over??
the e36 system will be essentially the same, in the way it deals with you blindly clamping your foot on the brake as a cat runs out into the road.
m3 might be programmed to allow more slip before it cuts in? but not much, cus bmw still want you to have as much steering capability under braking as in a 325i.........
later systems are able to chatter the brakes in and out faster but still come in at around the same detected slip %.......

just strip the abs out and learn to drive.

its like abs, traction, esp and launch control on formula 1 cars..... drivers championship my ass........ whats the point? great ive just won the formula 1 car STEERING championship!