abs delete? worth it?

[M3 euro ltw]

This is one of the reasons I removed my abs, when I put a different master cylinder on the car, I was never sure the abs was working as planned. Of course then I need an adjustable bias valve.

If you substituted a 23/23 for a 25/25 master, you've not changed the bias at all in terms of front to rear bias. You've actually just decreased pedal travel and increased the force needed to achieve the same line pressure.

Ie a stiffer, shorter pedal. (fine if you're strong)

I'd personally be careful with adjustable bias valves. They do not really work as most people believe they do.

http://www.stoptech.com/technical-support/technical-white-papers/proportioning-valves

The technical papers on StopTech's website are incredible and very, very helpful to learn some of the basics about how brake systems work. Just be aware that adjustable bias valves and static bias valves are nearly a thing of the past given how even next gen BMW (E36) did away with them as the EBD became more powerful.

EBD is incredibly "better" most of the time for determining the bias you want on your car because it can adjust it on the fly based on pressure sensors as well as speed signals showing impending (not yet!) lock up.

While most people agree that a performance set up will be 60-70% front biased, a quick reference to more modern cars (say E46 and on) will show a puzzling trend to biases closer to 55-60.

Why? Well, the EBD is so damn powerful in modern cars that you can take advantage of more rear bias safely under less than ultimate braking situations where the weight is all forward, and you need all the bias up front. A simple mechanical system without ABS and its built-in EBD will never be able to supply the higher rear bias you might want in many situations because of the static (or adjustable) bias valve, or need to set it to a pre-set and unalterable bias of say 65% front. The downside to this? Well, if ABS fails, you lose the EBD, and you lock up the rear so damn fast that the car will spin and be hard to control in MANY braking situations. (Ask S54 MZ3 drivers who've tried to do without ABS, its a disaster for them)

At the end of the day, if you set up your calipers, masters, pad Cf and rotor size (and a bias valve if cursed with it originally) to approximate the original mechanical bias of the native ABS system, you should be within range of what the EBD built in can compensate for, and run WAY better than without the ABS computer.

Top notch (read professional) drivers will insist on having adjustable bias because they will be able to feel the threshold where ABS kicks in for either EBD or brake pulsing vs what they know the car is capable of with perfect bias. They can adjust the bias via a bias bar so less EBD goes on... they're that good....

Just like an engine management system in closed loop can run very well, it may have to zero in on the right fuel mix, it will perform just a bit better if the map is spot on in the first place, and no "zeroing in" is needed. Like wise for an adjustable balance bar set up in the hands of a pro.

Data-acquisition for the "non-pro" amongst us will guide balance bar set up if one's butt is not up to the task. It might also allow one to test and fine tune an adjustable bias valve for DE or race use.

[Herr Faust Schinken]

How did you test it? Snow/ice surface? Rain?

we dont have ice were i live i just did it by panic stoping and it never seemed like it went on but then again the tires never locked ether but maybe thats just because of my tires

[browntown]

You see, every move the ABS computer makes is based on an EXPECTED result! If you mess around with bias through pads, BBK, bias valves or masters, the result of a timed valve change in the pump MAY NOT be as expected, and the ABS computer will believe its due to road conditions and wheel slippage that is changing... it will be faked out because you've messed with the mechanical bias... so you get into loops of poor compensation and BAD ABS results.

This is one of the reasons I removed my abs, when I put a different master cylinder on the car, I was never sure the abs was working as planned. Of course then I need an adjustable bias valve.

[yeaseth]

I took mine off because my ABS unit was bad and causing havoc on my brake system. Now that it's off my brakes work amazing. I won't get technical but the ABS unit was restricting the fluid going to my calipers and never even activated the whole time I had it(no matter how hard I slammed on the brakes in any weather condition) Since I've had such a rough time with my ABS I'm glad it's no where to be seen. In my case I'm gaining performance but I know that's not the case with people that have perfectly working ABS systems, just dont ignore the fact that your ABS units are probably 20 years old like mine was...

[jlevie]

The big advantage to having ABS is that you can still steer the car with ABS active. If the front wheels lock up, they slide and you can't steer. Having or not having a working ABS can be the difference in driving the car home or watching it hauled away to a crusher on a flat bed.

Go check modern pro race cars, everyone I have ever seen has ABS (and power steering) except a few classes.

The ABS light only comes on when there is a fault in the system. It does not illuminate when ABS activates.

[M3 euro ltw]

bias

So is the non-ABS factory cars bias controlled by the master or the proportioning valve or both?

I like to think of the bias in two ways.

There is a static bias as defined by the mechanical attributes of the car.

In this sense the master cylinder, the rotor diameter, the radial height (usually refered to as width) of the pad, the piston size of the, and the Cf of the brake pads chosen will define the bias ratio.

Masters come in two varieties. For the BMWs we drive, they are what is referred to as combination masters, ie two separate chambers for safety inline with each other, ether of the same diameter cylinders, or, perhaps staggered. For example a 23mm one is likely meant as 23 for front, as well as for the back. a 23/19 will refer to one that is 23 for the front, and 19 for the rear. (It is counter-intuitive, but the 19 means more bias to the rear... Think about it, the same lb of pressure over the smaller piston area results in more psi literally within the cylinder...lb per sq inch)

On the flip side, once you start actually pressing on the brake pedal, two items in the system might shift... First, if there is an adjustable bias valve or static bias valve, the more you press on the pedal, the more bias is shifted to the front. This is a kink in the curve, and only kicks in on the new angle after a certain point. (that point is adjustable with a variable valve) But ALSO...and ABS system might adjust the bias. The current term for this is EBD or Electronic Brakeforce Distribution.

So, neither the master or the bias valve really "control" the bias, but they are part of what defines the bias.. the former is static, the latter will depend on the internal line pressure as to where its set.

Alex.

[ELVA164]

coming from someone whos first experience driving was a big chrysler without abs i can say that driving without abs freaking sucks, however im not sure the ABS in my e30 works the light never comes on and i don't think its ever come on

How did you test it? Snow/ice surface? Rain?

[Herr Faust Schinken]

coming from someone whos first experience driving was a big chrysler without abs i can say that driving without abs freaking sucks, however im not sure the ABS in my e30 works the light never comes on and i don't think its ever come on

[M3 euro ltw]

RE: ABS removal

There is a ton of misguided information in here.

Even an early ABS system like the E30 is going to help you in nearly all situations brake better and perform evasive maneuvers better, and allow safe driving in rain/snow/oil situations vs without it.

The idea that you can simply remove it and have better braking ignores MANY engineering principles.

First off ABS systems are almost always coded and internally programmed around a specific mechanical bias for that application. Certainly in modern cars, and to a lesser extent older cars, the bias is VERY likely to be shifted from that bias which is optimized for use without ABS. Plus or minus a static bias valve is just the tip of the iceberg. This is done with bias valves, brake compounds, rotor diameter, piston diameter etc.

Even early ABS systems have a degree of Electronic Bias adjustment so that if the rear is locking up, pressure is relieved in the rear line(s) to allow it to catch up. This ABS function is not even the pulsations we all come to associate with ABS working... its something most people don't even know goes on.... and yet it allows for better braking and traction. (EBD is the modern term)

Remove the ABS system and a car with slightly higher rear bias for use with ABS suddenly becomes a car that locks up in the rear too quickly. Mess with the master cylinder and change from a staggered to unstaggered, or the reverse, and you're CERTAINLY at risk for making a system that is now outside the compensation parameters of the ABS brain, and quite possibly lengthening braking distances.

Put on aggressive pads at just one end? Might as well put in a staggered master! You've just radically changed the Cf of that end, and spoiled the bias that the ABS computers is programmed for.

There are so many ways you can screw up an ABS system that its not even funny.

You see, every move the ABS computer makes is based on an EXPECTED result! If you mess around with bias through pads, BBK, bias valves or masters, the result of a timed valve change in the pump MAY NOT be as expected, and the ABS computer will believe its due to road conditions and wheel slippage that is changing... it will be faked out because you've messed with the mechanical bias... so you get into loops of poor compensation and BAD ABS results.

There was an excellent point made that you can still threshold brake with ABS, and its therefore unlikely to lengthen your stopping distances in the dry... It can really only help by possibly identifiying the rear as near lock up, and releasing pressure to help STAY in the threshold braking in the rear.

At any rate, removing the ABS to enhance braking is just plain mis-guided on a street car. There is a remote possibility that if you restrict your racing or DE to dry days, and delete ABS, delete bias valves, and install a dual master with bias bar that you can fine tune your brake system to outperform the factory system in a small set of limited circumstances... but you're likely a very, very skilled driver at that point with a ton of experience in track driving without ABS....

Just my 02 cents worth.

(been doing a lot of research on these issues, and hope to have some pretty slick product available to you guys to enhance braking and transplant options soon)

[MonkeyMadness]

Was just coming in here to ask these questions and found all the need answers...
thanks

[yeaseth]

That videos awesome

[seatown88]

Anybody who deletes ABS without adding a bias valve is an idiot, IMHO. :)

Just throwing it out there, I run deleted ABS as our rules require it, without adding in a proportioning valve, and am currently satisfied with my brake balance. The fronts are the first to lock up, as discovered while going a little too deep into the brake zone at Portland International Raceway.

Some pad fade could be a contributing factor for the front lock up versus rear, as the indicated brake rotor temperatures were just above optimal levels. But overall I wouldn't change the stock balance much if at all.

[yeaseth]

I had a bunch of problems with my brakes, I ended up replacing everything except the abs and I still had problems getting my brakes to work even with my foot shoved down on the pedal. I easily deleted my abs with these lines http://www.youtube.com/watch?v=617yN...Ra6XJ759vLmjsg and my brakes work perfectly now.

[sweet6e30]

i removed my abs, it was dead weight and inoperative. cleans up the engine bay, braking was the same just dont forget to keep the proportioning valve for the rears!

[homegrone30]

Sounds possible