The Brakes Thread

SON240sx Automotive
1

I figured since this topic comes up way too often for comfort, it should finally be adressed. And what better time to address it, than when the idiot that ruins it, is still banned.

Two things you need to care about when you do brakes, torque and heat.
Torque is what actually stops your car, it’s a combination of a couple of things, the rotor radius, pad area, and pad friction. Rotor radius isn’t really the radius of the entire rotor, it’s from the central axis of the hub, to the centerpoint on the pad. This is the moment arm you’re working with, and if you know a thing or two, you’ll know that torque is equal to force x moment arm, so this is a pretty important part. The pad area is a bit self explanatory, more pad area, more friction, more force. Same thing with the friction coefficient of the pad.
So this is all pretty simple, right? WRONG.
Brake torque is damn near irrelevant most of the time, as the engineers at Nissan, Honda, whatever the fuck, do a pretty decent job of figuring out what’s appropriate to bring your car to a dead stop.
So why would you want more? Well, unless your car is faster, or heavier than stock, you wouldn’t, it would be a ridiculous waste of money, and so on and so forth…
So where’s the hard part?
HEAT
You got it, this is where it all gets really hairy. Brakes convert torque to heat. Since energy is conserved, the harder you stop, the more heat you put into your brakes, and if you stop really often (like on a track), you keep putting more and more heat into your brakes, and they start to fail.
Couple of reasons why brakes fail: The pads aren’t designed to operate in that heat range, and lose friction. This is why people get race pads, as they are designed to keep working when your brakes are glowing hot. But there’s a limit to even the temperature that the pads can tolerate, so you have to “help” them.
Brake ducts are some of the best and most affordable help you can give to your pads. Just get some ducting from home depot, rip out your inner fender liner, and with some work, you’ll have baller brake ducts like the race teams. I’m not gonna go into making brake ducts, because one, it’s easy, and two, you can find it almost anywhere.
The other issue is your brake fluid, it can only tolerate up to a certain temperature before it boils and it starts to lose the properties it had before. Your pedal becomes mushy and spongy, this is why it’s reccomended that you bleed brakes after every trackday.
Do bigger brakes help? Yes. Their larger rotor area allows more heat to be dispersed within the rotor itself and keeps the temperatures a bit lower, also the larger rotor area is better at dissipating heat, but not by as much as you’d think. They also help in the fact the additional rotor diameter and pad area compensates for the lost pad friction.

To summarize:
If you want to race, get better pads, it will be the best bang for your buck by far in terms of stopping performance. THIS is what really prevents fade, and helps you get the laptimes you want. If that’s still not cutting it, consider getting brake ducts, they are affordable, relatively easy to do, and give great rewards.
If you’re still finding your braking system inadequate after this, feel free to go big brakes, but I can assure you that with stock power, and these modifications, if you’re still fading, it’s YOU, not the brakes.

2

Nicely written.

I don’t think anyone will debate anything that you’ve said - I think the big debate comes up when we start discussing specific brake calipers which is completely retarded because nobody ever actually considers the more important parts - the pads and the fluid.

I don’t quite understand the technicalities that go further than the actual rated temperatures on bottle for the fluid but maybe someone could further explain how the brake fluid absorbs water and becomes less effective as it heat cycles, etc.

Solarian has accurately described the physics of how the brakes work - this will likely get a little more hairy once we start talking specific brakes and calipers.

Personally I’ve tracked multiple times with z32 front (hawk hps) / stock rear (hawk hp+), and I’ve also tracked multiple times with 180sx front (hawk hps) and stock rear (hawk hps i believe?)

there are very slight sign of fade when I’ve pushed the 180sx brakes to the limit and after doing some ducting on the car it helped a LOT (like Solarian suggested above) but did not completely rid the car of the problem.

On the other hand, the same pads with no ducting on the bigger z32 calipers (and therefore bigger pads and larger rotor diameter and thickness) show no signs of fade on the same track even on a higher horsepower car.

there is another major disadvantage to larger brakes also, which is sprung weight. Sprung weight is a very important factor in suspension, but that discussion should probably be left for another day.

3

The best way to summarize this thread is as follows:

Are you cheap and willing to live with sub-par? Buy Pads.
Are you not cheap and want the best? Get a real brake setup with larger multi piston calipers and bigger rotors.

4

although that may be true max I wouldnt say that summarizes this thread at all. Nobody spoke about cost for one…

Also, it depends on your application - if you are street driving you’re fine with good pads, fluid and rotors and stock calipers. That doesn’t make you a cheap ass runing sub-par brakes, does it?

5

If you are talking specifically about the stock 240sx brakes, then I will have to disagree. Stock brakes on 240’s are garbage even with good pads and rotors. I actually got brand new pads and rotors when I bought the car and they still were pretty scary on the highway… all I had to do is brake hard couple of times and the brakes would have been almost gone… not to mention that most people have rusted calipers which are seized half the time on pretty much any 240.

Point is, upgrade those calipers on the 240. Don’t be cheap and just buy pads and rotors. Cheapest (by far) are the z32 front brakes with conversion lines. Pads for these are cheap and so are the rotors. There’s no reason why people shouldn’t buy them. I mean, they spend god knows how much getting rebuilt calipers, new pads, new rotors and so on… if you add another couple of hundred you can have much better brakes.
Keep in mind, those front z32 calipers came stock on S14 (K’s) Silvias. Just that alone should be convincing enough.

6

nocwage = ahmed?

7

Solarian clearly spoke about cost:
“will be the best bang for your buck”, and yes it will but that statement clearly means saving money by cutting corners.

Also most of the post was about preventing fade, something you won’t get unless you are driving hard. Doesn’t necessarily have to be “track” but if you are fading your brakes it’s because your are driving pretty damn hard.

So if you just drive on the street and the way you are driving on the street isn’t causing any fade or other problems then stock is fine, pads, calipers rotors, all of it.

If you track your car you can ‘make do’ with nice pads with stock setup, the price you pay is chewing through expensive pads VERY quickly as well as warping rotors and more frequent brake fluid changes. It wouldn’t take long before you would have been better off buying a larger setup that required less force (thus less wear) to slow you down…

If you’re upgrading your pads or brakes you probably already have better tires which would allow you to take advantage of more brake torque than before.

So it still comes out the same
Cheap and sub-par to ‘make do’
or Baller and excellent for those taking things seriously…

I should point out I just have a cheap 180sx/SE-R brakes with HAWK HPS pads and not a baller setup so I’m not trying to justify my own purchases.

8

Saving money and cutting corners is a different story though.

You could be possibly justifying your own future purchases.

9

I disagree Lith.

I agree that some people may have brakes that arent in good shape maybe for one reason or another but I personally drove my stock s13 pretty hard at some points and never once experienced fade.

I also raced walters ka-t s14 on stock brakes and although they would fade eventually it took at least 4 to 5 laps of very hard driving to do so… it doesnt matter waht you’re doing on the street, you could never generate even half of the heat that you can on a race track.

Some people have bad luck with stock brakes, and I’ve never had a chance to invetigate the issue myself but I have a feeling there is something failing in the caliper, sliders not being lubed and maintained properly perhaps causing uneven pressure (single piston sucks for that)… i really have no idea what it could be without actually looking at someones brakes who have the issue.

10

Also remember, the size of your rotor is directly proportional to the size of your penis.
That’s what this thread is REALLLY about.

That’s why Porsche drivers get all the chicks.

11

Not matter what pads / rotors you put on 15 year old brakes fluid is 15 year old brake fluid. If you fully flushed the system with new brake fluid I’m confident you would not have experianced fade street driving.

Did you know its recommended to change the stock (DOT 3) brake fluid ANNUALLY! I don’t know many people who do that, and the ones I know who do never experiance brake fad on the street with a stock setup. The most overlooked part of brake upgrades is the fluid.

Coles notes* Change your fluids annually or semi annually its not water and it will lose some properties after a while.

12

Seconded! I’d rather have brand new DOT3 than 5 year old race fluid…

13

Front Z32 brakes are worth it imo, just because generally they are quite affordable. However, they are not necessary for most. All that they would add, is brake torque that isn’t being used anyway, and a bit less fade due to larger area to dissipate heat in.
I would personally not reccomend all 4 corner Z brakes like I had on my car, as you can use the money for better things.
It’s not about being cheap or cutting corners, it’s about prioritizing your money where it will do the most good. As in, your tires. Always.

14

I’m sick of repeating myself on this topic…if I can lock up my fronts when running 225/50R15 v710 slicks with 180sx calipers, HP+ pads, and experience no fade with the use of rbf600 fluid with my stock motor. Why would you upgrade to more unsprung weight by going to 300z brakes or uber 4-piston brakes?

I was not able to max out my brakes in any respect. I’m sure this setup would work well with a stock SR and mildly upgraded one with some ducting.

Everyone wants BIG brakes, you buy the biggest brakes needed for your power output and wheel sizing so that you don’t experience fade and are able to lock them if needed. If you are experiencing either fade or unable to lock, your brakes are too small (if you have exhausted even hawk HT-10’s)

Andrew.

15

nah anderw you just suck

300zx brakes are such a joke for my car that i actually laugh at them every day

i anhilate a set of hawk front pads in a single session, as soon as they overheat once its game over

my brakes run way too hot

i need to upgrade

fluid boiling = soft pedal

pad fade = stiff pedal

remember, street cars have no brake ducting at all so the brakes will retain heat for quite some time, lots of high speed to traffic light braking can fade pads surprisingly fast.

16

8:30AM - Wake up
9:00 - 10:00 Shower, brush teeth, etc…
10:00 - 10:30 Have breakfast
10:30 - 12:30 Laugh at 300ZX brakes

17

Sasha, you know guys like us are different. Your laying down a lot of hp and braking from 240-250 kph (maybe more) at the end of the back straight. I can understand 300’s not being enough in this case. You have loads of heat to dissipate. Me, I had like 120whp, I can’t get my car going fast enough.

Also, you run HUGE wheels, this is factored into brake torque needed to stop those bastards. You have weight long ways away from the center of your hub.

I can say that none of the guys on this board will be at your level, and half will never be at my level. They have no need for anything bigger than 300’s, yet everyone argues about it.

Adam for example had no need for anything bigger than 300’s, he was running blank rotors and Hawk HT-10’s, and laying 400whp. He didn’t have big wheels and tires though, he only ran 16’s and 245 Hoosiers, and was on Mosport GP once or twice.

Sometimes I do suck :stuck_out_tongue:

Andrew.

18

Ok, there was a lot of reading. So if what I’m about to say has been said, disregard it.

How fast you stop also has a lot to do with your tires. Afterall they’re the part actually making contact with the ground and carrying the weight of the car.
Shit tires are not going to stop nearly as quick as new tires.
And, low quality performance tires won’t stop you as quickly as race tires…

19

I have 300ZX brakes because they look cool when I take my wheels off. People are like “Yooo Jonn, sick brakes, are those like Ferrari brakes?” And I’m like “Nah man, they’re from a Bugatti.” And they are like “Fuck Top maaaaan” (if anyone knows french people, they understand this.)