No ABS?

[Jean]

ABS is the anti-blocking system. It keeps the wheels for locking up. A locked wheel will have much less stopping power than a wheel at the threshold. Older cars such as e30s had a rather primitive ABS programming (still much better than its US counter part of the days). If one wheel locks, it kicks back on the rake pedal releasing all four wheels.

Personally, I think it is still great for most everyone driving on the street or with only average rack experience. But people who track their car may prefer to regain full control on their brakes. It is possible to remove the relay to disable ABS, or install a switch.

I was kidding :) My 318i does not have ABS, I've only been in 1 close call when I locked my brakes up in rain and quickly got off the brakes and applied the brakes gently to stop sliding into a truck in-front of me that slammed on his brakes....

No issues in auto-x either ....

[RangerGress]

I followed the ABS thread at Bimmerforums but stayed clear of it so as not to get crushed. My perception is that ABS was designed to help the driver retain control, not to stop the car quickly. I'm not convinced that ABS will stop you faster then genuine threshold braking.

The ABS in my car didn't work for months. I tried hard to perceive lock up because flat- spotting tires was a problem. What I found is that it was not always easy to detect that one of the 4 wheels had gone beyond threshold and was now locked up. The changing variables of weight on that tire, car speed, and the nature of the road's surface made detection of a wheel locked up occasionally challenging. The experienced racers at BimmerForums all made it sound like it was easy to detect lockup. Ok, I'm a relative newby, but there were times when it wasn't easy. There were times when I could not feel it thru the wheel, pedal nor butt, especially when the road was smooth. What I had to detect was a sudden unexpected and slight change in braking g's, that couldn't be accounted for by all the other things that were happening. I was blowing thru a tire each weekend.

A SpecE30 is not that tightly sprung. Maybe that is another reason that it was harder for me to detect a locked up wheel, then some of the anti-ABS racers at BF.

Finally I got my ABS working. All it took was reconnecting the light in the dash and replacing a relay. ABS makes it obvious that you are on the brakes too hard. So it's the perfect signal that you need to back off a little. I don't know that I would use ABS to stop me, but I'll certainly use it as an indicator to back off the brakes a little.

[E30 Racer]

ABS is the anti-blocking system. It keeps the wheels for locking up. A locked wheel will have much less stopping power than a wheel at the threshold. Older cars such as e30s had a rather primitive ABS programming (still much better than its US counter part of the days). If one wheel locks, it kicks back on the rake pedal releasing all four wheels.

This is absolutely false. The ABS (antilock braking system) monitors wheel speed via hall effect sensors at each corner of the vehicle. When a wheel begins to lock (known as longitudinal wheel slip), the ABS will reduce the amount of brake line pressure of the effected brake circuit (NOT necessarily at each wheel unless each wheel is demonstrating a propensity to lock). The reduced brake line pressure allows the effected wheel to regain some rotation, and the cycle repeats. On dry pavement, maximum braking occurs at approximately 15-20% wheel slip.

Generally speaking, even professional drivers will be unable to outperform the stopping distances achieved by ABS.

I would, without question, encourage drivers to retain ABS on their cars (especially if they are street driven). Once you are able to achieve consistent lap times, and feel like ABS may be adversely affecting your lap times, disable it and see what happens. Only then will you be able to conclusively determine whether *you* are better off without it.

[BrewCity11]

^ good comments

I would have to agree.

I would disable it first before completely removing it. Did anyone answer the OP's question about how to correctly disable it?

[SimonH]

This thread is making the rounds :D. He's my take. I'm faster with the ABS period. I love hearing people turning off their ABS because they "think" they are faster or can brake better. Honestly if you can threshold brake better than the ABS system lap after lap then you should be driving professionally. I could go on but I won't bore you. Now your braking system is a little different since you don't have a booster and it is a custom setup. At least with that setup i'm guessing you will have an easier time driving with out the abs and being able to feel the lock up. Having said that being able to drive without the ABS is a good skill to have, it will give you a good understanding of where the real threshold is without it being masked by the ABS and if heaven forbid your ABS does fail you won't flat spot all 4 tires in the very next corner. If you want to try that go for it, put on some old tires though . Overall I don't recommend running without it, unless there is something wrong with your system.

[RangerGress]

Disable ABS by removing the little rectangular relay that is under the dash above driver's left knee. The relay is not on a board of relay's, it's by itself.

E30 Racer, I figure that anyone that knows what a "Hall Affect" is, is worth listening to. But just to doublecheck that I understand...lets say that max braking occurs at 10% wheel slip...at what point does E30 ABS kick in? Maybe 1% slip? Maybe 50% slip? That's the crux of the issue. In order for ABS to be more effective, it has to restrain itself from kicking in too early, and then only reduce wheel slip to 10% (in this example). If it reduces wheel slip to 0, then the potential for being a hinderence is there.

I'm not disagreeing overall. I'm happier now that my ABS is working again. But it's good to understand exactly how things work, instead of just sort of understanding how things work. And the way to understanding is to ask questions. So I'm asking.

[E30 Racer]

...lets say that max braking occurs at 10% wheel slip...at what point does E30 ABS kick in? Maybe 1% slip? Maybe 50% slip? That's the crux of the issue. In order for ABS to be more effective, it has to restrain itself from kicking in too early, and then only reduce wheel slip to 10% (in this example). If it reduces wheel slip to 0, then the potential for being a hinderence is there.

The ABS threshold will vary somewhat, depending on how much friction is available (i.e., what surface you're on). That said, ABS should be expected to activate once an allowable slip level has been exceeded, not before.

Just a point of reference, 0% slip = a free rolling wheel. 100% = a locked wheel.

[danny325is]

Erik,
I would disable the ABS for now and see how you like it and you better test it for a while in both the WET and the Dry. You may be great in the dry but the moment the track gets wet you will be sliding all over the place.

You can disable it by pulling the ABS relay. see pics of the relay here. http://peakracer.com/peak-racer-race...abs-relay.html

my 2cents, unless your a pro driver, there nothing that can hurt you by keeping the ABS. I know we all dream about being that pro driver ( just ask Ranger) those rides are few and far between. when you turn pro you can have your pit crew take out the ABS while you sit in the motorhome with all the babes.

[einstein57]

i've never had any e30 with functional ABS. Come to think of it inly one out of the 10+ cars i've owned had ABS. I think if one day my ABS actually worked it would scare the crap out of me.

[Lance Racing]

What are your goals for driving? If your goal is to be a better driver, then lose the ABS. If you are going to keep ABS, then might as well drive an automatic so you don't have to learn the art of shifting either!

I've raced an E30 for 7 years and instructed with our local BMW club for 15. My race car has never run with ABS. And I never felt I was being out-braked by other E30s on the track with ABS. In fact, a couple of them have had the dreaded ABS lockout and had no brakes at the worst possible moment and had big crashes.

Our class (PRO-3) last year banned ABS (there are 25+ E30s in the class), in part because our class is about driving skill and we wanted everyone in the class to be able to really learn to use the brake pedal and not just stand on the brake pedal and have the ABS do the work for them. For those that fear flat spotting a couple of tires, just learn to use the brakes skillfully. I've only flat spotted 2 tires in 7 years. Also, you won't flat spot 4 tires at once. If you are marginally over-braking the car, only one tire will lock up. If you are locking up 2 or more tires you are over-braking the car WAY to much.

Oh, because we run a spec class, the brake rotors and calipers must be stock. We are able to run an aftermarket pad.

Anyone can drive the car from apex to track-out. Anyone can go down the straight and go through the gears. Good drivers are able to brake and carry good speed through the first third of the turn. That is what separates the good from merely average drivers.

[Hallen]

Shouldn't you be unpacking your car at Portland right now? :)
I hope to be up there on Sunday, I will try and stop by and say hi.
Monday will be my first track day with my dedicated track rat E30 that I have been building for the last three months. The ABS is non-functional right now... it's most likely the relay but I haven't checked.
What is this "dreaded ABS lockout" that you mentioned?

[PiercedE30]

"Dreaded ABS Lockout" is when the ABS system fails for one reason or another.

I will be excited to try out the 4 channel ABS that I will start working on later this summer.

[george graves]

details(on the 4 channel ABS)?

[Lance Racing]

What is this "dreaded ABS lockout" that you mentioned?

In my context, we've seen problems with an E30 going into a braking zone and when you go to the pedal, the pedal is rock hard and you have no braking at all. Not a good feeling when you are 10/10ths on track doing 120+ at the end of the straight. You have to get off the brakes for a slight moment, somehow they cycle, then you get back on the brakes and you have brakes. Problem is if you really leave your braking to the last bit, then to have to get off the brakes means there is no way you will make the turn. Thus the big off and possibly a wrecked car if there is not good runoff.

The ABS on an E30 is really rudimentary. We think it is more designed for the occasional use in the wet, but not in a high performance setting as a routine way to slow the car.

I've experienced it once while driving another PRO-3 car in an enduro, when we had 4 drivers doing stints in the car. Got the rock hard brake pedal going into T1 at Portland. It does not happen every lap, so you don't know when you'll get it, and when the brakes will be OK.

[Emre]

I currently have ABS in my track car (a '91 318is). But I still threshold brake. The ABS hardly ever comes on. If I start to feel it coming in, I'll back off a bit until I'm threshold braking again. I've gotten to the point where I literally cannot remember the last time I've triggered my ABS in the dry, though it does kick in from time to time in the wet.

Basically, the system is there in case of emergencies, but not something I rely on. I think this is in keeping with how the system was designed to be used.