StopTech Trophy

[O-cha]

Originally Posted by BookerM3

Wow, that's harsh...

Likely the number one limiting factor in most modern BMW's is the
ABS (with G sensors). Under dry conditions with good tire the ABS will kick
in before you have maximized the available braking performance.
(r-compounds and slicks really highlite this point)

This said larger brakes can offer improved stopping distance over the factory
set up, since fade can occur even in a single brake application. The only
way to know is to actually test it. From a drivers perspective, if the new
brakes improve initial bite, pedal feel and modulatation this translates
to the feeling of improved stopping distances

The ABS doesn't use G sensors to determine activation point, it uses wheel speed sensors. Only after one or more wheel is traveling considerably slower will it activate. I don't know any car that uses a G sensor to determine ABS activation, though some do use it as an extra factor to limit activation.

Un balanced brakes will activate the ABS very early as you lock the rears up before the fronts are even near the threshold or vise versa.

[ZStig]

isn't initial bite usually decreased with bigger brakes until they're well warmed up?

[BookerM3]

Originally Posted by O-cha

The ABS doesn't use G sensors to determine activation point, it uses wheel speed sensors. Only after one or more wheel is traveling considerably slower will it activate. I don't know any car that uses a G sensor to determine ABS activation, though some do use it as an extra factor to limit activation.

Un balanced brakes will activate the ABS very early as you lock the rears up before the fronts are even near the threshold or vise versa.

OK, The best example I can share is the E46M3 ABS. The standard version
on later M3 uses the Teves MK60, then there is the CSL and Competion package
version which has a higher threshold of activation and lastly the Race version
which has user adjustable settings. All of these units use the same basic
hardware the only difference is the SW. If the ABS threshold was based
strickly on wheel speed all units would activate at the same time under the
same conditions. However there is a noticeable difference with all three,
especially under bumpy conditions.

BTW - I was referencing the G-Sensor since this was the easiest way to show
when BMW changed there ABS systems to reference more than just wheel
speed. They reference Brake line pressure, G and yaw as well as WS.

[BookerM3]

Originally Posted by Roffle Waffle

isn't initial bite usually decreased with bigger brakes until they're well warmed up?

Temperature dependence is mainly affected by the brake pad material.

When I was saying innitial bite I was refering how the brakes react with the
same amount of pedal pressure upon brake application. One set up may
a very high initial level of friction while another initial frition may be lower and builds.

[The HACK]

Originally Posted by BookerM3

OK, The best example I can share is the E46M3 ABS. The standard version
on later M3 uses the Teves MK60, then there is the CSL and Competion package
version which has a higher threshold of activation and lastly the Race version
which has user adjustable settings. All of these units use the same basic
hardware the only difference is the SW. If the ABS threshold was based
strickly on wheel speed all units would activate at the same time under the
same conditions. However there is a noticeable difference with all three,
especially under bumpy conditions.

BTW - I was referencing the G-Sensor since this was the easiest way to show
when BMW changed there ABS systems to reference more than just wheel
speed. They reference Brake line pressure, G and yaw as well as WS.

I had to look this up. I think you're confused between the DSC (stability control) system and ABS controllers. There's no difference between the E46 M3, M3 with Competition Package, and M3 with CSL when it comes to the ABS sensor, they all use the same ABS sensors but the difference is in the DSC control unit (Dynamic Stability Control). There's no difference in ABS threshold but there is a difference in when DSC will intervene to prevent the car from skidding. If you brake in a straight line, when all three cars are equipped with the same wheels and tires, on the same surface, given the same weight, they will all stop the first time just the same despite the obvious difference in brake hardware. The ONLY difference is when you try to brake in a corner, where DSC might be more forgiving on the CSL and Competition packages and allow certain slip before intervening to keep you in line. And there may be some differences in the 2nd or 3rd immediate applications after depending on how much heat is in the system.

But the entire point about upgrading to bigger brakes offering immediate improvement on stopping distance? Pure bull. Even Zeckhausen will tell you otherwise:

http://www.zeckhausen.com/Testing_Brakes.htm#Summary

Between the stock 350Z track brakes and the StopTECH big brake kit, the stopping distance for 100-0 actually increased slightly on the same RE040 tires with StopTECH's kit. And notice the BEST stopping distances are all within a statistical anomaly of each other. Where you WILL see improvement on a big brake kit is if the test is repeated time and time again, the fade resistance part of a larger heat sink is going to dramatically impact the result (see how the "average" distance improves with big brake kits).

And as far as calling each other names...I think the public will likely know who's blowing smoke and who actually knows what they're talking about here, O-Cha. At least *I* don't have an ulterior motive here (I no longer have any associations with RacingBrake, nor any brake vendor/manufacturer).

[BookerM3]

Originally Posted by The HACK

I had to look this up. I think you're confused between the DSC (stability control) system and ABS controllers. There's no difference between the E46 M3, M3 with Competition Package, and M3 with CSL when it comes to the ABS sensor, they all use the same ABS sensors but the difference is in the DSC control unit (Dynamic Stability Control). There's no difference in ABS threshold but there is a difference in when DSC will intervene to prevent the car from skidding. If you brake in a straight line, when all three cars are equipped with the same wheels and tires, on the same surface, given the same weight, they will all stop the first time just the same despite the obvious difference in brake hardware. The ONLY difference is when you try to brake in a corner, where DSC might be more forgiving on the CSL and Competition packages and allow certain slip before intervening to keep you in line. And there may be some differences in the 2nd or 3rd immediate applications after depending on how much heat is in the system.

But the entire point about upgrading to bigger brakes offering immediate improvement on stopping distance? Pure bull. Even Zeckhausen will tell you otherwise:

http://www.zeckhausen.com/Testing_Brakes.htm#Summary

Between the stock 350Z track brakes and the StopTECH big brake kit, the stopping distance for 100-0 actually increased slightly on the same RE040 tires with StopTECH's kit. And notice the BEST stopping distances are all within a statistical anomaly of each other. Where you WILL see improvement on a big brake kit is if the test is repeated time and time again, the fade resistance part of a larger heat sink is going to dramatically impact the result (see how the "average" distance improves with big brake kits).

And as far as calling each other names...I think the public will likely know who's blowing smoke and who actually knows what they're talking about here, O-Cha. At least *I* don't have an ulterior motive here (I no longer have any associations with RacingBrake, nor any brake vendor/manufacturer).

Based on your comment looks like you were checking out ETK, note DSC
and ABS control is incorporate into the same units. Straight line braking is
affected by the this system the greatest difference is felt under bumpy
conditions the ABS kicks in later with ZCP unit. Without arguing further if
you research the topic a good driver without ABS can outperform a street
based system (on good rubber / in the dry).
The Teves and Bosch M4 sytems are another story.

Outside of the ABS debate, I agree that much of the hipe over big brakes is
not founded or realistic and mainly cosmetic. However there isn't
a black of white answer to whether all Big brakes increase or decrease / stopping
distances. The only way to prove right or wrong is to do back to back tests
with both factory and aftermarket brake using the same pad compounds and
temps. Brake pads play a major roll in the outcome.

In the end the only reason I commented was your harsh statement...

[Beedub]

i cant lie when i did my AP BBK i definatly noticed shorter stopping distances, i also noticed the with rear 4 pots the car doesnt stand on its nose like i used to, the rears a definatly taking up more of the braking........ i think the OP is pretty much bang on with what he's experiencing...

Ochas is correct, you really can leave mad tyre marks under really heavy braking..... infact it feels like something is going to break!! lol

OP can you post some "bedded in" pics, i love to see a burnished Rotor!!

[3002 tii]

Originally Posted by BookerM3

... From a drivers perspective, if the new
brakes improve initial bite, pedal feel and modulatation this translates
to the feeling of improved stopping distances

Agreed but I would say initial bite is a function of the pad, not the big brake kit.

[O-cha]

Originally Posted by BookerM3

Based on your comment looks like you were checking out ETK, note DSC
and ABS control is incorporate into the same units. Straight line braking is
affected by the this system the greatest difference is felt under bumpy
conditions the ABS kicks in later with ZCP unit. Without arguing further if
you research the topic a good driver without ABS can outperform a street
based system (on good rubber / in the dry).
The Teves and Bosch M4 sytems are another story.

The ABS can be reconfigured to allow for more or less wheel spin before activating, this is quite possibly done between different models. It does not change the fact the ABS is activated by a difference in wheel speed and not Gforce. Period. There is no discussion on this point.

Additionally, ABS activating or not under bumpy conditions is going to have a lot more to do with suspension tuning anyways. Tires losing contact with the surface will IMMEDIATELY activate abs, anyone who has races on a track with rough spots and ABS will tell you this, turn 16 at Sebring has a rough patch right in the racing line notorious for activating abs.

The reason a good driver can "outperform" abs is because ABS is not, and was never intended, to allow a driver to stop faster, in fact activating abs makes your stopping distance LONGER. ABS is there for one reason, to allow panicked drivers who would otherwise lock up their wheels to be able to steer around an obstacle instead of careening straight into it because they locked the front wheels and can no longer steer. It does this by pulsing off the applied brake pressure.

A really fun test you can do is put some tires on your car that are grossly mismatched in diameter, then speed to 100mph and try to stop, you will scare yourself as ABS activates without hardly any wheel slip and your brake distance is extended 100s of feet.


Knowing this about ABS alone should tip you off as to why it is more then possible that a brake upgrade that changes the balance can effect a decreased stopping distance.

Pretty much any test you do is going to be completely inconclusive, you aren't controlling the variables at all by just doing a back to back comparison, by design they are going to require different testing conditions to provide optimal performance to begin with.

[O-cha]

And Hack, I told you I agree with your basic premise but the things I presented are facts, that you refuse to admit you overstepped by making a sweeping generalization (that is wrong) while berating a user, thereby making an ass of yourself, is not my problem.

You cannot submit any rebuttal to my stated fact that the stoptechs provided better balance on MY setup specifically because you don't have them, you don't know my setup.

You also cannot submit a rebuttal to the fact that I stated it's quite possible the brakes made it EASIER for him to threshold brake much better, because you stated this yourself.

If I add a proportioning valve to a brake setup, it sure as shit is going to make me stop faster (assuming rears are over-sized). It has nothing to do with the size of the brakes or the calipers, but them matching the car better. You cannot disagree with this, and yet this is essentially the statement I have made, that it is possible for the change in brakes to be more then just a difference in size and type. Therefor your sweeping generalization is proved wrong, have a nice day.

[mfanatic325]

Gentleman, gentleman...we all know....size isn't everything...






I had to

[ZStig]

All I know is when slowing down at close to the thresh-hold from 125mph, I'd much rather have bigger and better proportioned brakes than on my stock brakes

[esqu1re]

[ZStig]

Originally Posted by esqu1re

[3002 tii]

Way too much arguing here. I think we can all agree a big brake kit is most beneficial in addressing fade issues which would only result on the track. Any improvements seen/felt on the street by OP are real but presumably could've been achieved with ss lines and better pads. Hack, O-cha are both right...

[BookerM3]

O-cha - We are going to have to agree to disagree on this topic.

BTW - Did you actually try the test with all the funky tire sizes?

[O-cha]

Originally Posted by BookerM3

O-cha - We are going to have to agree to disagree on this topic.

BTW - Did you actually try the test with all the funky tire sizes?

On accident yes actually. There is no disagreement, disagreements are on opinions. You believe you're right, I know you're wrong.

I don't feel like uploading the actual technical literature, so here's the first hit for "BMW ABS" I can assure you the technical literature also states it's based on wheel speed.

http://www.bmw.com/com/en/insights/t...ke_system.html

Again you are correct that brake line pressure, G and yaw sensors are fed through the DSC module, but I assure you these are for DSC.

[BookerM3]

Originally Posted by O-cha

On accident yes actually. There is no disagreement, disagreements are on opinions. You believe you're right, I know you're wrong.

I don't feel like uploading the actual technical literature, so here's the first hit for "BMW ABS" I can assure you the technical literature also states it's based on wheel speed.

http://www.bmw.com/com/en/insights/t...ke_system.html

Again you are correct that brake line pressure, G and yaw sensors are fed through the DSC module, but I assure you these are for DSC.

You called me out. I did not disagree with all your points but was not
willing to put in the effort to agrue futher.

I am not saying that the ABS system does not look at WS.
What I am saying is that in modern systems G sensors/yaws sensor/line
pressure,... are factored into the operation of the ABS. Based on what
information are you assuring me that I am wrong? Are you sure other data
is only used for DSC?

See attached info on the Bosch M4 System it touchs on the inputs and the
design parameters of street / race systems.

http://www.bosch-motorsport.de/conte...rochure_en.pdf

Originally Posted by O-cha

1- The ABS can be reconfigured to allow for more or less wheel spin before activating, this is quite possibly done between different models. It does not change the fact the ABS is activated by a difference in wheel speed and not Gforce. Period. There is no discussion on this point.

2- Additionally, ABS activating or not under bumpy conditions is going to have a lot more to do with suspension tuning anyways. Tires losing contact with the surface will IMMEDIATELY activate abs, anyone who has races on a track with rough spots and ABS will tell you this, turn 16 at Sebring has a rough patch right in the racing line notorious for activating abs.

3- The reason a good driver can "outperform" abs is because ABS is not, and was never intended, to allow a driver to stop faster, in fact activating abs makes your stopping distance LONGER. ABS is there for one reason, to allow panicked drivers who would otherwise lock up their wheels to be able to steer around an obstacle instead of careening straight into it because they locked the front wheels and can no longer steer. It does this by pulsing off the applied brake pressure.

A really fun test you can do is put some tires on your car that are grossly mismatched in diameter, then speed to 100mph and try to stop, you will scare yourself as ABS activates without hardly any wheel slip and your brake distance is extended 100s of feet.


4- Knowing this about ABS alone should tip you off as to why it is more then possible that a brake upgrade that changes the balance can effect a decreased stopping distance.

5- Pretty much any test you do is going to be completely inconclusive, you aren't controlling the variables at all by just doing a back to back comparison, by design they are going to require different testing conditions to provide optimal performance to begin with.

1- WS is the primary input, without a speed differential in one or many
wheels = no ABS, however other sensor inputs affect how and when the ABS
will react.

2 - If you remove suspension settings from the equation, more preformance
oriented ABS Systems will not lock up as easily as a street based units. Ask
any of the top running Grand AM GS teams (almost all of them run either
the Bosch MS / or Teves MS units)and they will confirm that not all ABS
systems respond the same in bumpy conditions.

3- This is the point I initially raised. ABS is a limiting factor in min. stopping distances.

4- Changing brake balance can definetly affect brake performance both
positive and negatively. Most street cars have too much front bias.

5- Agreed

[O-cha]

Originally Posted by BookerM3

You called me out. I did not disagree with all your points but was not
willing to put in the effort to agrue futher.

I am not saying that the ABS system does not look at WS.
What I am saying is that in modern systems G sensors/yaws sensor/line
pressure,... are factored into the operation of the ABS. Based on what
information are you assuring me that I am wrong? Are you sure other data
is only used for DSC?

BMWs technical literature, no one makes a plain ABS unit anymore that I know of, they ALL have traction control functions integrated in them now.

I don't see the point you were making with this statment then

Likely the number one limiting factor in most modern BMW's is the
ABS (with G sensors). Under dry conditions with good tire the ABS will kick
in before you have maximized the available braking performance.
(r-compounds and slicks really highlite this point)

It appears you're saying under high Gforces ABS will kick in, I can't interpret that any other way. And that's where this stems from.

[johanness]

*yawn*

I'm sure there's a happy medium somewhere for less than $8000++

Nice brakes either way, congrats OP

[JCz04Bimmer]

Is it strange that the only thing I really envy about a BBK setup is the ease at which you can change brake pads?

[Beedub]

Originally Posted by JCz04Bimmer

Is it strange that the only thing I really envy about a BBK setup is the ease at which you can change brake pads?

its very strange.... then again if you dont track your vehicle, i guess its not, the stock brakes are great for the road imo and offer great pedal feel, and retardation.....

These type of BBK kits come into play really when you doing a decent amount of track days, but i have to admit, being able to swap the pads out in 8mins a side once the cars in the air is awesome..... i run pagid blues which are great at the track and seem good on the road at the cooler temps as well.......