Truth about Big Brake Kits: Balanced Braking Systems

[Fobio]

I rarely look at PAS Mag for performance advice, but this is good stuff by StopTech...article/written by Dave Pankew for PAS MAG...I also now understaad the true benefits of corner-weighing the car.

Stoptech: Balanced braking System (http://www.pasmag.com/performance/reviews/958-stoptech-balanced-braking-systems?q=big+brake)



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An upgrade is not an upgrade when it has a negative impact on your vehicle’s performance. Brake upgrades can often fall into this category as performance enthusiasts pursue a “bigger is better” mentality without putting consideration into the concept of optimum brake bias for their vehicles, which is also known as having balanced brakes.

Optimum brake bias is obtained when a vehicle's front-to-rear brake force ratio (or force bias) exactly matches that vehicle's dynamic front-to-rear weight distribution (or weight bias). We say dynamic here because when a car is braking we have the obvious weight shift forward taking some of the static weight that was on the rear wheels and shifting it forward.

The braking systems goal then is to distribute brake force so that all four tires are simultaneously generating deceleration proportional to the four individual dynamic corner weights with only a slight calculated front bias for stability. This will maximize brake efficiency and consequently minimize stopping distance.

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It is purely the combination of these two factors, brake force and dynamic corner weight that determines a vehicle's optimum brake bias. Therefore, when selecting a big brake upgrade, one should be aware that changing the force (or torque) output of the front brake components without changing the force (or torque) output of the rear brake components can cause an undesirable shift in bias.

The most dramatic brake bias mismatches are usually brought about by big brake "upgrades" which are not properly matched to the intended vehicle. How can this occur? Any time that a bigger front rotor is installed there is a simultaneous need to decrease the effective clamping force of the caliper to offset the increased leverage and therefore torque created by the larger rotor. Unfortunately, too many of these "upgrades" do not take this factor into account, and those applications end up with both bigger rotors and the same or larger pistons which serve to drastically shift the brake bias forward. As a result, stopping distances can go up dramatically.

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So why does brake bias matter? On the race track, out-braking your opponent by just two feet every lap might not sound like much, but over the course of a twenty lap sprint race it can result in a three to four car length advantage at the checkered flag. To the racer, decreased braking distance is the same as free horsepower. On the race track during qualifying or a timed lap mode these effects are amplified, as out-braking your opponent by a few feet every lap can result in a multiple car length advantage by the checkered flag. During wheel-to-wheel racing the advantage can result in a safe legal pass as well rather than cutting it too close.

On the street, improper bias can also lead to shorter effective brake pad life because a set of brakes not contributing as much as they could be will lead to higher front rotor temperatures and more front pad wear – the opposite of what should be the goal. In most cases drivers will experience earlier and greater ABS activations too.

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For obvious reasons, the risks are highest when upgrading only one set of brakes and rotors. StopTech is the only brake upgrade company providing proper brake bias with front- only brake upgrades. In fact they have a trademark on “Balanced Brake Upgrades” as a term. This is of course key if your budget or the rules only allows for upgrading the front brakes and the rear will never be a factor.

Benefits of Balanced Brake Upgrades™

* Shorter stopping distances

* Firmer brake pedal

* Improved brake modulation

* Reduced brake pedal travel

* Optimized for ABS performance

* Optimized for OEM master cylinder

Source:
StopTech
Balanced Brake Upgrades™
www.stoptech.com

[Dave_The_BMXER]

Nice read. I think a lot of brake upgrades people do are geared more for adding to the mods list and look than actual performance gains.

For example I know a lot of people who upgrade to BBK's so that it fills the rim better rather than for performance reasons, and personally I made the mistake of going cross drilled without doing proper research into the fact that they are worse and more prone to cracking.

Live and learn I suppose...

[Fobio]

whatever you do to your car cosmetically, it shouldn't degrade it's OEM performmance evelope, ESPECIALLY in an area as crucial as braking.

just something to keep in mind when you drop $2000 on a BBK (or even an OEM upgrade from MZ3 to MS3 front rotors), and EXPECT performance, you better double check to make sure you're getting what you paid for. And one way of doing that is also getting coil-overs and corner-weighing your car...but cosmetically, that may not be as pleasing depending on your application. live and learn for me as well!

[wildfrisco]

This is the kind of post I was looking for.

On another forum I documented my OEM BBK upgrade, front and rear for my 2.3 liter Mz3 sedan. I had a question about brake bias but as far as we could tell, there were no helpful posts in that area. The only thing I kept in mind (which I'm not completely confident about) was to somehow preserve the factory brake bias when upgrading.

[Kevin@nextmod]

whatever you do to your car cosmetically, it shouldn't degrade it's OEM performmance evelope, ESPECIALLY in an area as crucial as braking.

just something to keep in mind when you drop $2000 on a BBK (or even an OEM upgrade from MZ3 to MS3 front rotors), and EXPECT performance, you better double check to make sure you're getting what you paid for. And one way of doing that is also getting coil-overs and corner-weighing your car...but cosmetically, that may not be as pleasing depending on your application. live and learn for me as well!

I do agree with what you say here but lets be honest here. Most of the members or people that mods their cars, mainly mod it to look nice. Like Dave said, some people just buy the bbk to fill the wheels. It might not be an upgrade as the article said but i don't think it'll be worst for their daily driving applications. Unless they are going to track with it as well, i don't see how big of a difference in degrading it is.

But thats just what i think. =)

[Egierda]

And this is EXACTLY why I went with Stoptech for my BBK.

[Olestra]

I would like to ask a noob question:

How easy is it to corner weight your car? What type of shop should you be looking for and how easy are they to find?

[G-daddy]

So what's the moral of the story? As long as I get a full set of brakes from a Speed3, it should be balanced?

[Egierda]

So what's the moral of the story? As long as I get a full set of brakes from a Speed3, it should be balanced?
Not necessarily.

If you replace every component, then yes....but, simply swapping rotors, calipers and brackets may not do it. The reason I say "may" is because I'm not a 3 guy so I can't say for certain, but I would imagine that the 3 and speed3 don't share other components like master cylinders, etc.

[wildfrisco]

So what's the moral of the story? As long as I get a full set of brakes from a Speed3, it should be balanced?

Mazdaspeed 3 and Mazda 3s (2.3 liter) rear rotors, calipers, brackets, and probably the pad material are identical. So you'd probably need something in addition to balance out the rear. I went with larger Mazda 5 rear caliper brackets and rotors.

Brake pedal feel/travel/effort/modulation is excellent so I didn't opt to change out the brake booster (if they're different) and master cylinder.

Although I'm using stock pads up front and stock equivalent pads rear, braking performance has improved dramatically. Just need to somehow "fine tune" it if possible.

[G-daddy]

Not necessarily.

If you replace every component, then yes....but, simply swapping rotors, calipers and brackets may not do it. The reason I say "may" is because I'm not a 3 guy so I can't say for certain, but I would imagine that the 3 and speed3 don't share other components like master cylinders, etc.

Thanks for the explanation. Looks like I may have to take an in-depth look into the entire system.



Mazdaspeed 3 and Mazda 3s (2.3 liter) rear rotors, calipers, brackets, and probably the pad material are identical. So you'd probably need something in addition to balance out the rear. I went with larger Mazda 5 rear caliper brackets and rotors.

Brake pedal feel/travel/effort/modulation is excellent so I didn't opt to change out the brake booster (if they're different) and master cylinder.

Although I'm using stock pads up front and stock equivalent pads rear, braking performance has improved dramatically. Just need to somehow "fine tune" it if possible.

I don't understand...so a stock Mazdaspeed3 is built so that its front brakes work with in conjunction with its rear brakes, perfectly biased. Shouldn't this same exact system be kept when swapping to another car?

Hmm...then again, a MS3 is more front heavy, so the fronts are a lot stronger when swapping to a Mazda3. This will give it more front bias, thus, you get bigger Mazda5 brakes to balance it out. I see now. Is this why?

Oh, where do you get Mazda5 brakes? I doubt many Mazda5 owners mod their cars and swap out brakes.

[wildfrisco]

I don't understand...so a stock Mazdaspeed3 is built so that its front brakes work with in conjunction with its rear brakes, perfectly biased. Shouldn't this same exact system be kept when swapping to another car?

Hmm...then again, a MS3 is more front heavy, so the fronts are a lot stronger when swapping to a Mazda3. This will give it more front bias, thus, you get bigger Mazda5 brakes to balance it out. I see now. Is this why?

Oh, where do you get Mazda5 brakes? I doubt many Mazda5 owners mod their cars and swap out brakes.

The Mazdaspeed 3 is several hundred pounds heavier than a naturally aspirated Mazda 3, but I don't know how much more if it is in the front.

But you definitely want to upgrade as a system/whole. I keep reading about folks that upgrade the front brakes only, and often times end up with longer braking distances. I can tell you that my stopping distances have decreased more than noticeably and there's more braking capacity. There are other Mz3 drivers that have done the Ms3 fronts only, then later upgraded to rear Mz5's and stated that afterwards it felt more balanced.

I was easily able to get low mileage Mz5 rear brake components from dismantlers (http://www.car-part.com/) for a good price. Another thing I wanted to add is that rear Mz5 caliper pistons are 19mm smaller than Ms3/Mz3s (2.3 liter) rear caliper pistons...so one might be able to play/adjust by just swapping parts.

[laksman91]

And this is EXACTLY why I went with Stoptech for my BBK.

You kinda contradict what is being said in the article, by only changing the front

[MajesticBlueNTO]

I do agree with what you say here but lets be honest here. Most of the members or people that mods their cars, mainly mod it to look nice. Like Dave said, some people just buy the bbk to fill the wheels. It might not be an upgrade as the article said but i don't think it'll be worst for their daily driving applications. Unless they are going to track with it as well, i don't see how big of a difference in degrading it is.

But thats just what i think. =)

here's putting it (degraded performance) into perspective in terms of daily driving....numbers are representative not actual:

let's say OEM brakes stopping distance from 60 km/h is 150 ft

let's say BBK stopping distance from 60 km/h is 155 ft

that 5 ft could mean the difference between 1) hitting the kid that ran out into the street or 2) rear ending the car in front because the BBK gave a false sense of security

[Egierda]

You kinda contradict what is being said in the article, by only changing the front
Not at all. The BBK doesn't change brake bias because StopTech engineers the front non-race BBK calipers to be application specific (different piston sizes) and maintain OEM brake balance/bias in front-only upgrades. If I had gone to a front-only race-only BBK, then you're absolutely correct, I'd need the rears to balance it out.

Based on your comment, you're missing the ENTIRE point of the article.

The reason I went to a BBK was to combat brake fade and maintain more consistent braking under constant heavy use (ie. on track days). OEM brakes in 90% of cases are strong enough (hence the fact that they can lock up your tires easily) but do not provide the heat cycling capacity and resistance to fading that a larger rotor can provide. If you simply want to decrease your one-stop braking distance, buy stickier tires.