big brake kit.

[sickyute]

Originally Posted by cappykd

Thankyou. That was what I was wondering.....

"EPD
EBD: Electronic Brake Distribution (or Electronic Brake-force Distributor) - alters how much of the brake force goes to the front and how much to the rear. Cars always have more braking on front as if the rears lock before the front then the car will spin. How much braking you can do with the rears depends on how much weight is in the vehicle so EBD dynamically adjusts this balance. Without it, the manufacturer sets up the balance so the rears don't lock when the vehicle is empty which is less braking than is possible when the vehicle is full. "

If that's what EBD does than won't the car be able to compensate automatically for the front BBK??? CZ-75?

that's what i thought....
cuz it does it dynmaically .. which is to say it can compensate on the fly kinda and that it's kinda smart to know what to do when...

hmmmmmmmmmmmm

this thread is very good ... i'll sticky ..

[blaznhot_23]

Originally Posted by cappykd

So if EBD will dynamically adjust the balance then a front only BBK shouldn't have a problem.

exactly....thats why the rears i think should not be as beefy as the front...plus most manufacturers do not put a proportioning valve for that reason. if you had a EBD along w/ a propotioning valve it would defeat the purpose of having teh EBD on its own...

[sickyute]

Originally Posted by blaznhot_23

isn't 4 piston a little too much for the rears since most BBK for the front are 4 and some 6??? plus as you said before the cost of teh mini caliper almost reaches that of a BBK for the front. I think dual piston in the rear is more than enough especially for a car the size of the FG...what do you think?

according to the article...
EBD should take car of that ... lol ... j/k ...
but i agree with you as i think 4 piston is overkill in the rear...
4 piston is more than enough for me for the front ...

[sickyute]

stickied....

[blaznhot_23]

u da man marvie...did i rep you for this thread??? i can't remember???

[CZ-75]

Originally Posted by cappykd

Does anyone know how EDB effects the brake bias? Does EBD enter into the equation?

Speculation here, but EBD is supposed to act like a continuously variable proportioning valve under control of the ABS unit's algorithms for wheel slippage/loss of traction. This may be finite, however, in that the engineers may have only anticipated a certain number of braking g's and the system may default to not letting the brakes lock, as is described in the stoptech links provided earlier by aki. So, what you still end up having is a system that cannot deal with inputs beyond what the engineers anticipated and wrote into the code, albeit a more refined and flexible system otherwise, within its limits.

NASIOC.com is a good place to find good braking info from actual engineers in the field, at least it used to be.

[CZ-75]

Here's some info from one of the NASIOC engineers I referenced:

http://www.geocities.com/nosro/abs_f...20Distribution

It sounds as though this is set up to reduce rear brake force, not increase it.

[sickyute]

so the question is how far did the engineers go???

[sickyute]

Originally Posted by blaznhot_23

u da man marvie...did i rep you for this thread??? i can't remember???

nope....
good looking out.

[blaznhot_23]

weird...the board is kicking me back w/ the good ol' "you must spread rep before giving it deal"...

*edit*...finally got my rep in

[CZ-75]

http://www.geocities.com/nosro/abs_f...%20aftermarket

What happens if I install aftermarket tires, wheels, brake linings, calipers, springs, . . . ?

It is anybody's guess. Tires and brake linings are fairly safe items to experiment with. Having said this, I will point out that I am familiar with at least one case where the installation of high performance tires (where smooth-riding all-season tires were original equipment) resulted in a reaction with the suspension that ABS had not been tuned to anticipate. In this case, the installation of high performance tires resulted in significantly longer stopping distances because the extra tire traction was causing the front suspension to literally bounce off the jounce bumpers repeatedly, causing very violent changes in tire grip that ABS was not expecting. From a strictly ABS standpoint, it is best to stick with a tire, wheel, or brake lining that is similar in characteristic to the original equipment parts, or at least similar to any of the parts that are available as an option on that vehicle.

Toying with the hydraulic system is slightly riskier. (This would include parts such as the master cylinder, calipers, and brake lines.) If you change the hydraulic characteristics of the brake system, you may reduce the efficiency that ABS operates with. For example, ABS may deteriorate from a 95% utilization of peak tire adhesion to a 90% utilization of peak adhesion. This is due to the fact that ABS is tuned to the hydraulic characteristics of the original brake system, as noted above. Another way to think of this is that ABS, like any other control system, performs some amount of prediction or anticipation to maximize performance. If you change the hydraulic characteristics of the brake system, you render the predictions or anticipations of the system less than ideal. That means ABS will need to react and adapt to the change. Reacting and adapting takes some time and this translates to lowered efficiency.

There are many variables that go into characterizing the hydraulics of a brake system and some are not always obvious. For example, if you install larger race-specifications calipers, you may assume that your new calipers will consume more fluid. This is not necessarily the case. It is true that larger pistons in your caliper will result in greater fluid consumption, but these race-specification calipers are probably also much stiffer than the stock OEM calipers. This stiffness actually reduces overall fluid consumptions. Also counter to your intuition, large race-specification calipers may have multiple small pistons than result in an overall volume displacement that is smaller than the single large piston in your original calipers.

A driving enthusiast may point out how a certain magazine tested a particular vehicle, after installing big brake calipers and rotors, that stopped 10% shorter than the stock car. The problem here is that these changes are almost always made along with a change from all-season tires to high performance tires or some other significant change. As I have noted above, engineers spend years tuning the ABS hydraulic controller to work well with the hydraulic characteristics of the brake system. It is true that your final braking performance may be superior (less brake fade, for example), but speaking strictly from an ABS perspective, it is a crap shoot.

More recently, the June 2001 issue of Car and Driver magazine featured a Roush modified Mustang, featuring race-specification brakes and suspension, and extremely low profile tires. They found the stopping distance to be surprisingly long given the quality of the parts. They attributed this disappointment to the fact that the ABS was not originally designed for such components - my assessment exactly.

In contrast, the September 2002 issue of Car and Driver magazine (they seem to appreciate brakes more than any other car magazine) featured a comparison of four aftermarket big-brake kits for the Subaru WRX. They expected the big-brake kits to show their mettle during their brake fade test, but they did not expect any stopping distance improvements with cold or merely warm brakes. After all, if the brakes can invoke ABS control, the vehicle must be tire-limited rather than brake-limited. However, with every big-brake kit, they found improvements in stopping distance even with cold brakes. There are many possible reasons why this is the case. My best assessment is that, according to my experience driving a Subaru WRX, the ABS was tuned to be very conservative in order to extract stability (resist spinning or oversteer) on ice, resulting in the trade-off of reduced asphalt performance. This is a classic compromise for ABS engineers. Installation of the big-brake kits may have fooled the Subaru ABS into a more aggressive ABS control (for example, with a shorter time between slip cycles) whereas the engineers had intended a more conservative ABS control (to improve resistance to spinning out). Put another way, I believe that the Subaru WRX with one of the big-brake kits featured in this article may have significantly reduced ability to resist spinning out on ice.

I know that StopTech makes aftermarket calipers that are custom tailored to each application by modifying the piston size to closely match total piston area of the stock vehicle. This is smart and shows due care. There may be others, but I have not researched this matter. (I own Stoptech products, but I have no relationship with them.) Some other aftermarket caliper manufacturers take a single design (with one piston size) and use it for everything from a sub-compact to a large sedan. In such cases, your results will depend on being lucky enough to have the one available piston size match your stock piston area.

Suspension modifications are another interesting area. Engineers spend considerable time tuning ABS performance while in an actual prototype vehicle. This means they are working with the entire vehicle - the entire vehicle includes the suspension. In fact, engineers will often find themselves working against the suspension. When you mash the brake pedal, the vehicle begins pitching as weight is transferred away from the rear tires and towards the front tires. This pitching can create difficulties in extracting the last 10 feet of stopping distance. ABS software is sometimes made to anticipate the pitching and to modify the manner in which brake force is modulated. Therefore, if you modify the suspension, you may be reducing the efficacy of ABS.

[cappykd]

Originally Posted by sickyute

stickied....

Thanks for the Sticky

+1 rep

[aki]

If that's what EBD does than won't the car be able to compensate automatically for the front BBK???

Upgrading only the front will still adversely affect brake performance even with EBD, because EBD application is contingent on the G force limits detected by the ABS system. The ABS computer will keep finding that the front brakes are exerting too much force, and will modulate the braking with the EBD to compensate. That continual modulation will increase your stopping distance. EBD doesn't change the programmed limits of ABS--it applies it.

If you get just the front brakes upgraded without the rear, you're guaranteeing longer stopping distances. The increased brake torque will inevitably put an excessive front brake bias that forces the ABS (and consequentially the EBD) to overcompensate. As I said before, the limiting factor in braking is the tires, not the rotors/brakes. If you want larger rotors to serve as a better heat sink, the pressure applied in the brake calipers need to be adjusted to compensate for the greater brake torque from the larger rotor diameter. Hence BBKs need the appropriate calipers to match.

For the money, and from tests, Stoptech seems to be the best bang for the buck. Just hold out and wait for them to release a kit. Si is a pretty major car, I'm sure they're not ignoring it.

[blaznhot_23]

teh si has been out for quite some time now...you would think aftermarket companies like stoptech would jump on it immediately due to the popularity of the car...

[sickyute]

i've emailed stoptech about this before ... like 6 months ago ...
they told me that they have not even started...
i asked them if the rsx-kit would fit seeing as we use the same brake pads and rotors ... and they said they didn't know but they'd look into it.
then i was notified when they released oem sized slotted rotors and i got these.

when i checked about a month ago on the status of the BBK ... i got no answer.

but other rsx brake parts are a direct swap ... even powerslot has confirmed this with their rotors and so has hawk with their pads ...
i don't know what's taking stoptech soo long ... there's obvioulsy more to it i guess?

just some food for thought.

[blaznhot_23]

i guess business is business...if i had a aftermarket company geared towards a certain product i sure as hell would push immediately to get my product out to make $$$ asap...but like you said...there must be to it than what we know...shame on you stoptech...

[sickyute]

brembo is out...
so is rotora ... 3 different front kits...
over a year and no stoptech bbk but only oem sized slotted or drilled rotors...
that's crap.

[blaznhot_23]

brembo is front only right?

[sickyute]

yesssiiiirrrr.

[blaznhot_23]

so still back at square 1 w/ some companies offering BBK for fronts...I hope ryan @ hpautoworks can work some magic w/ fastbrakes to come up w/ some killer complete BBK for our rides...