Floorman279

iTrader: (11)

1) what controls the brake bias in my 2000 fbody?

2)does pulling abs fuse effect the bias?

79_T/A

iTrader: (1)

1. The abs module controls brake bias.

2. Yes, it will bias further rearward. Not ideal.

Floorman279

iTrader: (11)

I had a feeling it was yes to both. That's y I can't understand y these guys pull the abs fuse and be like, "problem solved" after rear end swaps and abs inop. So basically it goes 50 50ish bias now?

Might have to do an abs delete shortly.

It's odd, my 02 taurus has a bad module and doesn't throw any codes, but have no abs and the rear wants to lock up in wet roads or hard braking. My camaro, when I get abs inop after a few min of highway driving, if I smash the brakes the fronts want to lock up. I have 555 on the rear and shitty sumis on the front. Could be contributing. Also have front c5 conversion so more power there. Just would think that the rear would want to lock up since more juice is going there

Floorman279

iTrader: (11)

Wait is it mechanically controlled inside the module, where even if the fuse is pulled brake bias is still ok cause the module still exisits, or Is it electronically controlled

79_T/A

iTrader: (1)

Electronically controlled

blackbyrd

iTrader: (14)

ABS delete is on my list for this exact reason, just putting it off until I buy my ctsv calipers

Floorman279

iTrader: (11)

I really like my abs tho. Dont ever need it much but its always cause im turning and hitting the brakes hard at the same time. Im not the best driver. Also the tcs is a bonus. While mid corner with 400 rwhp and 390s a little bump can make the tires wanna break loose if on the throttle enough. Thanks 79 for ur replies

Floorman279

iTrader: (11)

Im goona try one last effort to make my axles read correct. Ive got my old ten bolt axles out and im goona have a shop measure where those rings are sitting. Then pull my 9 imch axles and have them measure those to compare. If they are nearly identical, ill have them remove the new aftermarket rings and install the used rings from my 10 bolt. Lots of wasted money but i wanna try everything before i accept defeat on my abs woes

1 FMF

iTrader: (1)

2) does pulling abs fuse affect brake bias, not really but it's a loaded question/answer.

the abs module does not control brake bias... but in the end it does from a different perspective.
you can read about hydraulic proportioning valves found on older vehicles, and a big reason they were needed was when vehicles had drum brakes in the rear and disc/rotors in the front. disc brakes with rotors have the pads riding against the rotors with no gap. drum brakes do not have the shoes riding against the drum, there are springs that always force the shoes back inward away from the drum face so there's like 1/8" gap between shoe and drum and more as the shoe wears. because of this what was called the proportioning valve was needed to move the rear shoes first and get them to hit the drum and build some pressure before applying pressure to the front discs to get simultaneous brake affect at front and rear wheels. and then there was the front to rear bias to manage which was done by adjusting brake line pressure, and this idea is what everyone sorta clings to.

21st century stuff is all disc brakes now (rotors & pads) with pads riding against the rotor at each wheel. so each wheel inherently brakes at the same time when master cylinder generates brake line pressure, so there is no "proportioning" valve. but you still need some bias- more front brake force than rear because of weight distribution and momentum. this is handled inherently by larger front rotors and calipers versus the rear and not the ABS module nor other device controlling brake line pressure when the master cylinder generates pressure. You get the same brake line pressure at any wheel, at the same time, provided there's no air in the system and no other problem. then, when your brake bias is not ideal front to rear for a given condition then that's when the ABS module better known as EBCM electr. brake control module kicks in and can cycle brake line pressure to any wheel which then solves the bias issue dynamically- all you do is hold the brake pedal down as hard as possible generate maximum line pressure, and the EBCM will simply allow maximum brake force to happen without any wheel lockup. at this point if you needed more rear bias then you need more brake pedal force and the ebcm would relax the front pressure. if you need more front bias, the ebcm relaxes the rear line pressure. it's a good solution and economical from a manufacturer perspective since everything is disc brake, and big thing is you size the front caliper/rotor compared to the rear for the vehicle and the front to rear bias is basically solved.

http://www.aa1car.com/library/brake_balance.htm

typically rear brake pads would wear out faster than fronts,
every wonder why the smaller rear brake pads cost more than front brake pads?

if you were to put a heavier rear axle in or have more weight rearward, then you'd want more bias towards the rear versus the oem setting. pulling the abs fuse would prevent the PCM from operating the EBCM under it's oem programming expecting an oem 10 bolt with oem wheels and oem everything else that was planned for regarding weight distribution. does pulling the abs fuse change brake bias: no you still have whatever bias based on your front to rear caliper/rotor size. regarding ideal braking, i think you want 50/50 bias so that most of the time the rears are grabbing harder than the front with respect to the front/rear bias, so the rears would definitely lock up under just basic hard braking. and the extra/quicker/sooner brake force in the rear results in more stability and control, then when the rears lock up is when the ebcm adjusts the "bias" to keep the wheels from locking. when you have too much front bias and the fronts do significantly more braking than the rears is when you get out of control under hard braking.

Floorman279

iTrader: (11)

What ur saying kinda makes sense i guess.


Getting back to my taurus tho, has drum brakes in the back but no proportioning valve. My rears wanna lockup when u apply any real pressure to the brakes. Believe me, replaced everything and dealer confirmed saying its cause the abs module is no good.

79_T/A

iTrader: (1)

FMF, bias your brakes to the rear some more and do a threshold stop from high speeds in that 4th gen of yours and see how well that works for you.

1 FMF

iTrader: (1)

from a starting point of brake set up being ideal and front to rear bias is ideal, if you significantly increase rear weight of the car then what ever the front to rear bias was should change and go rearward. Such as if ideal was 70% front and 30 % rear it should start going to 69/31 and 68/32 and so on. I am not saying there is benefit to be had to simply change brake bias, definitely not without having all the correct info on your specific car and knowing what has changed.

The fancy phrase is dynamic rear proportioning. And because of it what I am saying is you probably already have closer to a 50/50 bias front to rear than what you'd think. It's designed in with the rear rotor and caliper size, and done to account for the range of weight to be expected on the car ( passengers, fuel tank size, trailer?). And now with drp and the ebcm you can have to much bias rearward and have the rear tires lock up quicker than old school brakes...

^^ exactly what will happen doing ABS delete on an oem setup.

With an ECBM and DRP, in the end it sort of doesn't matter if there is too much rear bias, it doesn't matter because the ebcm can modulate line pressure (to any wheel) and keep the wheel from losing traction. And in the end it's not about having some specific bias, it's about getting maximum brake force to every wheel under any condition without any wheel losing traction. And the rear brakes gotta do their share of the work... Not even they need to provide as much stopping as possible for any given condition. And can there be conditions when you want more braking on the rear than the front?

And if the fronts are over biased where the rears brakes leave work to be had, from a threshold stop you get nose dive as body momentum rolls over. Getting the rear brakes to contribute as much as possible at the same time as the fronts results in stability and control and with best possible braking, and rear brakes will prevent some of the nose dive by help taking care of decelerating that part of the car that otherwise would've been transferred over to the front brakes.

For your taurus drum brakes, I don't know anything about that car. I have the service manual for 2002 fbody so I have credible info how that system works and what to expect pulling the abs fuse. And you mentioned doing an abs delete, so there's the info regarding how things currently work at least to my understanding, if you do an abs delete don't crash into me I also found this online, might help with your... ford haha

1 FMF

iTrader: (1)

I believe you, and being 2002 it probably uses "dynamic rear proportioning". If DRP doesn't work via the EBCM like you experienced then drums would lock up because like you said there was no proportioning valve. And without some other line pressure reducing device and without the ECBM working the rear drums were seeing the same brake line pressure as the fronts and were over biased until you replaced your EBCM.