abs delete? worth it?

[Bearmw]

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

[homegrone30]

Yes the bias is determined by the master unless you add an adjustable proportioning valve. What he was saying is the front and rear pressures are different between abs and non abs because of different master cylinder sizing. So to get proper pressure you can either add a proportioning valve or swap masters.

[u3b3rg33k]

Select low is a wonderful thing, hmm? almost like a reactive version of the electronic-prop valves they use now.

The ABS delete question has been discussed ad naseum with no single "answer". Thought I would give you my take on the question so lighten up Francis.

Sorry, but Francis is being excessively irrational to improve his chances of survival. All your base are belong to us.

[browntown]

Yes the bias is determined by the master unless you add an adjustable proportioning valve. What he was saying is the front and rear pressures are different between abs and non abs because of different master cylinder sizing. So to get proper pressure you can either add a proportioning valve or swap masters.

This never occurred to me before, but I wonder if my m5 master cylinder changed the abs properties in my car and is causing my dislike of *my* system?

[homegrone30]

Sounds possible

[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!

[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.

[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]

That videos awesome

[MonkeyMadness]

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

[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)

[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

[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?

[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.

[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.