Brakes make you quicker??????

[volkerding95GSX]

Can you help my friend and I settle an argument?? I say brakes will give you faster circuit times. I say, straight from my dsm book,

"let's say ## coming up on an end of a long straight, neck and neck with a car that is identical to yours, with one execption: it has better breaks, you have to hit the brakes 100 feet before the corner, but ## competitor can hit the brakes 80 feet b4 the corner and achieve an identical cornering speed. that meanshe has been accelerating for 20 more feet, one whole car length and then some. guess what? you just got passed, thanks to you lousy breaks."

my friend disagrees and his points are, "well both those cars stop at the EXACT same place. Friction actually stops the cars. Not the friction between the pads and the rotors, but the friction between the tire and the road. A locked tire is a locked tire. And while big brakes can lock a tire without having to push the pedal as hard, stock brakes can still lock the tires instantly if you nail the pedal. Therefore, stopping distance and rate of slowing down, is unchanged. the actual stopping increase will be due to a decrease in weight/sq inch of tire, which can be achieved by reducing the weight of the car (driver or car) and by increasing the "stickiness" of a tire"

Who's right, do brake upgrades stop you faster or not? do they make you faster around a track or not?

 

[WolfsFang]

with my little knowledge of racing i would have to say they would make your lap times somewhat quicker. the reason i think is because with better brakes you would be able to stop later going into the corner due to better braking power.

 

[ramsack]

Upgraded brakes are for stopping faster if your tires don't lock up with stock brakes and for better high speed braking. You are both right and wrong. If you race on a circuit with a stock car with street tires and don't see that high of a speed then they won't help your times. If you have real tires and power to take advantage of big brakes then they will help. Upgraded brakes with exotic materials need to be hot to function the best too, so another reason there they could be pointless if you don't have the power to make use of them.

 

[BLINKY619]

dam dude i was thinking the same thing....... but i guess having to stop faster with less pedal force would be better since you may have more control over how much your brakes bite down..!!!!

 

[ramsack]

And to add when you lock the wheels completely you are not going to stop as soon as just being on the verge of slipping. Good ABS systems can stop you sooner if you are one if those people that just slam on the brakes. Your friend is an idiot if he thinks friction between the pads and rotors aren't doing anything to stop you. He doesn't understand friction. It's almost happening everywhere constantly.

 

[standard235]

More importantly, bigger brakes generate less heat which leads to fade. Upgraded brakes merely remain more consistent throughout abuse. Maybe the first lap out won't be faster but after 20 race pace laps, the upgraded brakes will shine.

 

[knochgoon24]

You're point is right.

Do either of you know calculus? It makes it really easy to explain. The distance you travel is the integral of the speed vs. time graph. If you brake later, you traveled further, and the distance under the curve is greater.

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But his point is right too.

There's no point using a huge brake setup with stock tires. And you wouldn't want to lock up the tires during a race. You can stop faster with a non-locked tire (ever hear of ABS?).

 

[clbd39]

hi, i'm the friend...

first off, we're talking the same tire, the same car, the same everything but brakes...

a set of 6 pot brembos has the same stopping power as a set of 2pot brakes correct?

one set is "easier" to stop while the other is a bit more difficult, resulting in pushing the brake system harder which may be more uncomfortable for the driver, however, both systems are capable of producing the same stopping power (lets assume stock tires, not some 325 wide sticky tires)

for this discussion's sake, lets look at what people are really talking about when you slam the brakes, the OH ISH!! slam the brakes type of stop or stopping at the rate at which you can slow down enough to avoid impact (since you dont always have to stop)

Why is that?

What stops cars? What is the ultimate force that determines what point the traveling vehicle will no longer be traveling?

Friction. Not the friction between the pads and the rotors, but the friction between the tire and the road.

 

[knochgoon24]

A great tire and crappy brakes aren't going to stop you any faster than a crappy tire and awesome brakes. There's a balance.

And locking up the tires isn't the fastest way to stop. You can slow down faster if the tire isn't slipping on the pavement. Look up static vs. kinetic friction.

Big brakes have larger rotors and pads. They are an upgrade because there's more material there to act as a heat sink. This decreases brake fade. It's not about slowing down for the first corner. That's easy enough. The trick is slowing down for the turn after that. And the lap after that. And the lap after that...

But you also need to match the pad to the operating temperature of the brakes. A brake designed for daily driving won't handle the heat of racing. And pads designed for racing won't get up to operating temperature and won't work as well because of it.

If you want to bring pedal feel into the argument, things change a little. The big brake kit has a larger pad, and with more pistons in the caliper, pressure is placed more evenly across the pad. With a larger rotor, the pads have a larger lever arm to apply torque. All these combined provide a setup that bites harder with the same pad compound and brake pressure.


I bet this argument started over the merits of a big brake upgrade. Just get some good brake pads, rotors, and some SS lines and be amazed at how much better the brakes feel. If you still have issues with brake fade then it might be time to look into a big brake kit. Most people just do it for looks.

 

[99gst_racer]

a set of 6 pot brembos has the same stopping power as a set of 2pot brakes correct?

one set is "easier" to stop while the other is a bit more difficult, resulting in pushing the brake system harder which may be more uncomfortable for the driver, however, both systems are capable of producing the same stopping power (lets assume stock tires, not some 325 wide sticky tires)

Not necessarily. I have a very difficult time coming to a quick stop at 140 mph on 2-piston brakes, but it's much easier on 4-piston brakes. Effectiveness of your brakes is relative to vehicle speed and the amount of heat being generated. If one brake set-up stops you sooner than the other, then you can use that difference in time for continued acceleration before braking (pretty much exactly what your buddy is saying). If both sets of brakes perform identically (doubtful), then your reasoning would stand.

In most, if not all circles of the world, a larger diameter rotor coupled with a better caliper (more pistons spread out across the rotor surface) will equate to better brake power than a smaller rotor and 1-2 piston caliper.

knochgoon24 is dead on the money as well.

 

[clbd39]

this post is made possible by the help of some of my fellow subaru guys, racing and brake fade has nothing to do with this situation, normal daily driving will not encounter these factors, of course in racing situations that happens

the argument about the tires skidding was not a reference to that being the quickest way to stop, however the moment JUST before that situation IS the quickest way to stop

First WRX, 170whp, bone stock brakes. 225/45/17s in a dot legal R compound.

Second car, whatever WHP, and $7k in brake upgrades. Stock tires. Heck lets even say they went to stock STI 225/45/17 RE070s
Send both cars down the same road, in the same weather conditions at the same speed. Have someone pull out in front of them.

Tell me, which one will stop short enough, or be able to slow down fast enough to avoid a wreck?

I bet more than half of you would pick the car with $7k in brake upgrades. Those people would all be in an accident

so, how does a car stop? the same as what gets it moving (in reference to the ground surface)? TIRES
What gets a car off the line faster? Less wheelspin... What gets you less wheelspin? Stickier tires.

What gets the car though a corner faster? More traction and what gets you more traction? Stickier tires.

Just like when you are trying to accelerate a vehicle, the amount of grip the tire has on the road, will determine how fast you can get moving forward (or backwards if you are a launch in reverse type of guy ) Its the EXACT SAME THING when trying to slow or stop.

OEM brakes have FAR more than enough power to lock up even a big wide sticky r compound tire.

People like to cite that the STI has a shorter stopping distance with its Brembos. The brembos have nothing to do with it. The RE92s have everything to do with it.

So at this point, you're going to argue, "well then why do they put brembos and big brakes on sports cars if they dont stop you any shorter"

So, the answer is the intended purpose, and as much as many people dont want to believe, LOOKS/CUSTOMER PERCEPTION.

The "intended use" for the STI is hard performance driving. Track days, racing, its a car with actual motorsport use in mind. Even if they have watered it down and softened it for normal day to day use, its still a car that was built for motorsport use.

Big fixed mount calipers with lots of pistons, and large diameter rotors offer something a floating caliper with normal sized rotors dont offer. Mass. More mass=more resistance to heat induced fade. They also offer a more consistant and precise pedal, which allows finer braking control into corners.

They also offer a look. Like the new WRX, look at how many people complain that they "downgraded" the brakes. When in fact, from a stopping distance standpoint, there is no change.

Look at the competition for the STI, the EVO. What would happen to STi sales if they removed the brembos and the EVO kept them? That would sway those people who are on the fence, a little more towards the EVO.

Finally, lets look at the group-N STI rally cars. What brakes do they run?

That's right, not the Brembos. They run the older FHI 4 pot/2 pot setup in order to clear the smaller rally wheels. Yet they stop JUST FINE. And those 4/2 pot are the same brakes found on a STOCK 06+ WRX

Lines, well lines are, from a stopping distance and fade standpoint, completely useless. Nail the brakes, things lock up rubber or steel lines makes no difference. Heat the brakes up, stainless lines have nothing to do with anything.

What lines DO get you, is a more consistent pedal, allowing more precise control.



Fluid, unless you are doing repeated hard braking enough to boil normal fluid, going to "upgraded" fluid, is a waste of money, and $18/bottle motul wont get you anything that $3 autozone fluid wont.


Rotors? NEVER an upgrade unless your factory rotors are damaged/very worn. Or if you go to a larger diameter rotor. Even then, that will only increase the amount of force per bit of pedal travel, to the point where they just lock up. Which would have happened on OEM sized rotors anyway. Slotted/drilled, at this point, is pointless and is for looks. Modern pads dont off gas like they used to, so having the slots/dimples/holes to vent off the gasses, well there is no need. Not only that, but 90% of drilled rotors will end up cracking. So if you want the look, GO FOR IT!, but buy a rotor that was cast with holes, not a solid that was drilled after. Break out the wallet though, and be prepared to search, not many people carry them and they arent cheap.



"BUT MY BUDDY PUT BREMBOS ON HIS CAR WITH WTFBBQ ALLOY PADS, SUPERBUTTSEKS INCREDITAINIUM LINES AND CHUCK NORRIS BRAND FLUID AND IT STOPS WAY HARDER."


No, it doesnt. It has a lot more INITIAL BITE.
95% of people will mistake initial bite and/or decreased pedal travel, for the ability to stop shorter.

A locked tire is a locked tire. And while big brakes can lock a tire without having to push the pedal as hard, stock brakes can still lock the tires instantly if you nail the pedal. Therefor, stopping distance and rate of slowing down, is unchanged.,




So what can you do to make the car safer if you up the power?

Well, for one thing, if you are driving responsibly and within the law, why do you need to upgrade the brakes at all? Ok so obviously that is a dumb point to bring up

No but seriously, you upped the power and you want the car to be able to stop shorter


Well, as we have established, the grip of the tire on the road is the ultimate determining factor, so you want wider and or stickier tires. Preferably, both.

There is another aspect to look at too. Weight. A heavy object takes more force to accelerate or decelerate than a lighter one.

Put your car and yourself on a diet.

In terms of the OP, this is a reasonable test for the difference in performance of a stock brake system compared to a modified one because we are talking about a single hard/emergency stop in a normal street driving scenerio.

However, in a real world/hard driving/track driving scenerio, repeatable stopping distance is actually more important than the performance of the braking system in a single hard stop. In other words, it is not only important that the braking system stop the car in "X" feet, but that it can do so consistantly under hard use. This is where a fluid with a higher boing point, better pads, etc. start to come into play.

This is also why I recommend that you pay attention to your braking system as you use it however you drive. If you do start to see signs of the system failing because of heat, etc. you need to modify the brake system to make sure that the braking system will perform consistanly in the conditions that you drive, what ever they are, and however much power your car makes.

 

[TSiAWD666]

Your friend is right, and you are right. The brakes can only exert so much stopping force as the tires permit. If you are locking up your brakes, you don't have enough tire. If you aren't locking up the brakes, you have enough tire so you can increase your braking force.

One thing he's neglecting is the additional heat dissipation and capacity better braking systems incorporate, at least theoretically. You get more mass in metal and fluid with a larger brake system to temporarily store the heat, plus better heat disspation in the rotor design to shed it from the system. A lesser system may reach heat capacity and boil its fluid effectively making that car's circuit times infinite Gotta finish the race to win.

Oh, you sometimes get a weight savings too. Lighter calipers, rotors, rotor hats, and hardware aren't anything to scoff at.

 

[red94gsx]

I think clbd39 is mostly right with his analysis. Stopping more consistently on a road course is key.

If anyone has ever driven on a road course before, they will recognize that driver confidence in the brake system is key. When you're traveling 100+ down a straight and need to mash on the pedal, you don't want the fluid to be boiling, the lines squishing, the pads disintegrating or rotors warping from heat, you just want it to STOP.

This is the main area that bigger brakes will help decrease lap times. In fact, as far as stopping distances are concerned, a lot of the time bigger brakes will stop in longer distances because often they are just thrown on the car without any tuning.

 

[cantgo2fast]

First off the argument was that brakes will give you better circuit times, nothing about daily driving. or "slamming on the brakes" because race car drivers dont do that. You are very correct in the fact that tires are the most important part of braking, theyre the most important part of a cars handling PERIOD why do you think F1 tires are $10000 a set.

I want you to think about where the energy goes when you brake. Almost all of it goes into friction aka heat.

The reason to buy stainless lines. bigger rotors and calipers is to allow those components to absorb the heat created during braking instead of your brake fluid. Why dont you want your brake fluid to get hot, because once it does it starts to boil and turn into a gas with considerably less density and it requires significantly more pedal travel to pressurize the calipers until it gets to a point where there isnt enough brake travel to stop the car.

So why do people uprgade their brakes? Well A LOT of people do it for looks but since were talking about road racers here they're doing it to go faster around the track. Which they almost always will with bigger brakes.

I want you to consider braking efficiency vs. braking power things like SS lines and pads will improve the efficiency of the basic components you already have.

SS will absolutely make a difference in braking. Why? because the SS makes the liness substantially stiffer which allows the lines to flex less under braking which means the same volume of the line which in turn keeps pressures up and boiling temperatures high. Once the volume expands the pressure in the line can then drop and the brake fluid can boil which is not good for braking especially if your on a road course and need to complete 20-60 laps. Find me a real race car without SS or harder brake lines.

Rotors will also make a difference because these absorb the majority of the heat created during braking. More rotor mass = more mass to absorb heat. This in turns equals more laps of hard braking without fade. I would say that rotors are a balance between braking efficiency and braking power which is why a lot of people upgrade them.

Pads are a simple upgrade that improve braking performance by creating more heat per revolution of the rotor than the stock pads. They're only useful however if the rest of your system (lines,rotors) can handle the extra heat.

Calipers come into play mainly with braking power. You need more power to slow down a larger car or slow down a light car in a shorter distance. Why does a GTR have HUGE brakes on it with 6 piston calipers because its a 4000lb car that needs to slow down from 160 on a track. That takes a lot of braking power. A lotus 7 on the other hand... not so much

In my experience with a full weight 2g, axxis ultimate pads, stock calipers and rotors, and dunlop star specs (the best street tire money can buy in my opinion) I can hit 135 on the back straight at HPR and after about three laps those stock lines and rotors are dying and subsequently i start to get brake fade, they only last about 6 laps before being scary to drive. You just cant tell if your going to plow into the back of the guy in front of you. Im going to start with SS lines and probably go to 13" rotors and possibly a 6piston front setup. I Would rather have as much braking performance as I can have and learn how to drive it properly than not enough. I can tell you right now the stock setup on our cars is NOT adequate for a race track. And I would argue that an EVO or STI is defenitely fast enough around a track to warrant brembos and big rotors

Your argument form a feel and modulation standpoint isnt really valid, the CSU FSAE race car has very little pedal feel, especially at the top of the stroke its very on and off, feel is better deeper in the pedal stroke. CSU FSAE

So if you want me to settle the argument. If you put the same good driver in a car with upgraded brakes he will be faster around a track than in the same car with stock brakes. Especially after 20 laps go to an autocross or track day and see how many competitive cars have stock brakes.

Sorry for the essay.

 

[volkerding95GSX]

YouTube - MITSUBISHI LANCER EVO IX - BRAKE TEST with DBA BRAKES

EVO brake test on youtube. Shows EVO stopping better with big brake upgrades and without tire upgrades. Thanks for the input guys!

 

[EclipticalGS]

One of you is talking about Track times, and the other is giving an example of an old lady pulling out in front of you...Were you guys drunk when you made up this argument? One of you said identical cars/tires, but different brakes, the other is talking about different tires, different brakes.

Circuit racing - Brake upgrades coincide with Tire upgrades, improving handling and braking around corners and to handle the abuse/ heat evacuation.

Drag racing- Going 150+ with little stopping room produces tremendois heat, brake upgrades are needed to a point, after that is a parachute.

Autocross/Roadrace - same reason as the Circuit racing.

It all comes down to which one of your reaction times are faster, when that grandma runs out in front of you.

As for the circuit, knochgoons graph was deadon for a braking situation but,
bad tires with stock brakes, wont always be worse than bad tires with Baer brakes, because one of you may have a different contact patch on the tire at that time on the same road. You cant really test braking on public roads.


Some of those larger brake kits actually weigh less too, and ive seen 13" rotors lighter than out stocks, which takes off rotational weight which is a plus.

Theres too many factors.....

If your comparing the same car, and just swapping out the brakes before and after tests, of course the $2000 brake kit will out perform, it should have more surface area, clamp area, and consistent pressure.

Good brakes dont make you any faster speed wise, it just helps your take corners in/out quicker, thus producing better lap times with no mechanical failures

 

[clbd39]

ACTUALLY... the original argument that we had was over the course of ONE SINGLE turn, not a days worth of mashing and destroying and brutal testing

 

[EclipticalGS]

Send both cars down the same road, in the same weather conditions at the same speed. Have someone pull out in front of them.

Tell me, which one will stop short enough, or be able to slow down fast enough to avoid a wreck?)

You wrote that.

 

[clbd39]

You're point is right.

Do either of you know calculus? It makes it really easy to explain. The distance you travel is the integral of the speed vs. time graph. If you brake later, you traveled further, and the distance under the curve is greater.
.

yes i understand physics, I'm an engineer, which puts me to be skeptic as well as try to rationalize and try to be logical

couldn't say this any better, so i'll let the website speak for itself

So you have your heart set on one of those new big brake kit upgrades for your street ride. They come with larger, vented, rotors and usually either 4 or 6 piston opposing calipers. Prices range from 800 usd to well over 1500 usd. Despite their high cost, they do not make your car stop faster, or decrease the stopping distance greatly. So what benefits do they propose?
The Physics Behind Stopping.

Physics doesn't discriminate between starting or stopping, but instead considers them both changes in kinetic energy. Thus, an object at a constant speed reacts the same as an object that is sitting still. That being said, the Standard Kinetic Friction Equation applies to stopping just as much as starting movement. In simple terms it says an object in contact with the ground will absorb the most kinetic energy right before movement, or sliding. This applies in the reverse as well: an car in motion will absorb the most kinetic energy right before the wheels lock up. With respect to modern vehicles, this equation states that the only way to make a car stop quicker is to either increase the coefficient of friction with the road, (e.g. upgraded tires) or decrease mass by lightening the vehicle. Note, both of these things have little to do with brakes.
Why Big Brakes Don't Reduce Stopping Distance.

As the physics lesson states, under braking, your car absorbs the most kinetic energy (movement) right before the tires lock up. This is true for both non-ABS cars and ones equipped with ABS. Abs shortens stopping distance by attempting to keep the brakes on the point of locking- where most kinetic energy is absorbed. Even though they have come a long way, even the most advanced ABS systems react by pulsing braking pressure resulting in a slide, roll, slide, roll pattern. In a perfect world, a perfect ABS system would perch the brakes at the cusp of sliding without ever actually locking up. Upgraded calipers and rotors in a big brake kit will result in more braking torque, the stopping force applied to the wheels. This will bring about wheel lockup or ABS intervention sooner than with the stock system. This should not be interpreted as a shorter stopping distance. In many instances the larger brakes confuse the stock ABS system which is not tuned to the different pressures required to engage and disengage the brakes.
What a Big Brake System Does to Improve Performance.

Big brake systems were not designed to stop your car sooner, but rather, stop it more efficiently and consistently. The larger calipers, vented discs, and exotic-compound pads increase heat capacity and heat dissipation. These upgraded braking systems not only perform well under extreme temperatures, but in most cases perform better when hot as opposed to average street driving temperatures. This is definitely something to consider when deciding on rotor and pad compounds. Because these brakes dissipate heat more effectively, they reduce brake fade. Brake fade occurs under high temperatures, can be caused by boiled brake fluid, and results in a soft pedal and elongated stopping distances. Big brake systems don't decrease your car's stopping distance over stock. Instead, they are designed to perform consistently under extreme conditions so that your car will stop just as well the first time as the N'th time.

 

[97-gst]

haha isn't this thread "bench racing"

 

[EclipticalGS]

Thus why my post has, heat evacuation, abuse tolerant, consistent clamping, etc.

 

[VETTE_50_TH]

I understand what the subby guy is trying to say. But its not like we are putting 8 piston brakes on a sundance. We are putting them on a car which comes from the factory with 205 or 225 width tires and in some cases people have spent 400 bucks for a decent set of tires. So yea, you might lock up, but these brakes have a much larger SA and do not require nearly the pedal to stop the car as fast as stock, and with with better tires, you could really mash the brakes and still not lock up.

I guess the subby guy needs to drive our car with stock brakes and then one with upgraded brakes and see how much of a difference there is.

 

[knochgoon24]

So isn't everyone in this thread arguing pretty much the same thing... even the OP and his friend?

Essentially:
If your tires suck, bigger brakes aren't going to help. Your stopping distance is limited by how much friction your tires have with the road.
If your brakes suck, better tires aren't going to help. You'll be limited by how much clamping force and resulting friction the brakes create.


You're arguing 2 sides of the same coin. Your stopping distance is determined by the weakest part of the system.

 

[EclipticalGS]

So isn't everyone in this thread arguing pretty much the same thing... even the OP and his friend?

Essentially:
If your tires suck, bigger brakes aren't going to help. Your stopping distance is limited by how much friction your tires have with the road.
If your brakes suck, better tires aren't going to help. You'll be limited by how much clamping force and resulting friction the brakes create.


You're arguing 2 sides of the same coin. Your stopping distance is determined by the weakest part of the system.

Winner.

 

[Zac692069]

i like this thread. my thoughts, bigger brakes mean less stress on the brake system and better stopping power. but with good brakes you need good tires!