Donny Boy

I would love to have my RX-8 with super huge disc brakes on all 4 wheels with prominent calipers, addind beauty and function to my car.

Any input??

Hercules

The brakes are pretty big as it is.

Look here, you can tell

wakeech

and it's sort of a big fat marketting myth that bigger brakes add performance...
they don't, really. if the brakes can lock the tyre, then you need stickier tyres first, in order to stop faster.

Sputnik

There's a difference between hamfisted stabbing at the brakes to lock them up, and modulating the brakes at the limit. Gimme any underbraked car out there, and I can lock the tires up for ya.

At the same time, I can make the tires on a stock Miata squeal at launch, does that mean that it has too much power?

---jps

Rich

This was already discussed here.

The summary is that big brakes *hurt* performance, unless you're going to take your car to the track. They increase unsprung weight, and do nothing to reduce braking distances, as long as they are capable of locking the tires. There are links on that thread to a Car and Driver test of aftermarket brake setups.

If you want them for looks, go ahead. Just realize that just because something (wing, big wheels, big brakes, lip spoilers, drilled rotors, etc) comes as a part of a "performance" package, that doesn't mean it helps performance.

Sputnik

That link to Car and Driver is invalid now.

If it is the same article that I am thinking of, they tested a couple of front-only brake kits. That alone will actually hurt braking performance, not improve it. A balanced, 4 wheel setup is another matter altogether.

And the other issues depends on what comes with the car to begin with. Mind you, if Mazda is deciding between two different sizes of brakes, then the bigger set will increase unsprung/rotational weight. That's why most cars, especially non-sports cars, are designed with brakes that are below the capabilities of the stock tires (and yes, those brakes can still lock up tires when pushed too hard). Most people don't need the increased brakes, so they provide the cars with better handling.

But depending on what parts you use, you can increase braking size and capability in alot of cases, and decrease unsprung weight at the same time. The setup I put in my Miata (click my homepage for details) actually weighs less than the stock setup.

Mind you, whether the RX8 needs bigger brakes or not has yet to be determined.

---jps

Rich

Ok, explain this to me. If the brakes are strong enough to lock the tires, how could *even stronger brakes* decrease stopping distances? The brakes have already grabbed so hard that the wheels are stopped completely! How much slower than 0 rotations can they go? If the brakes are strong enough to lock the tires, making them stronger can't help in any way that I can see. Like I said above, we're not talking fade here, which shouldn't be experienced on public roads at any time, just pure stopping distances.


I agree on these two points. You can upgrake brakes and decrease unsprung weight, which will improve the handling performance and fade resistance.
Also, there is a possibility that the RX-8 will have such bad brakes that it won't be able to lock the tires. I find that pretty unlikely, however.

Hercules

I think locking tires is bad anyway

The idea to stop safely is to pump the brakes properly and quickly.... something that ABS does automatically. Pumps faster than humans can do. That's what you feel the jumps in braking, it's pumping.

Rich

You make 2 excellent points. It's true that locking the tires is bad, but it's a good measure to see whether or not your brakes are up to the task of providing maximum braking power. There's really nowhere to go once you've got braking power that is so strong that it overpowers the grip of your tires.

(btw, I realize the joke, and thus the smiley; I just wanted to drive that point home.)

ABS is a good thing to bring up, and I logged on to post exactly that, but you beat me to it. One thing upgraded brakes can offer is better brake feel, in addition to fade resistance and different unsprung weight. In a car without ABS, upgraded brakes can decrease stopping distance for just this reason. However, I'm assuming that the RX-8 will have ABS and brakes that can lock the tires, and the combination of those two things leads me to strongly believe that supersized aftermarket brakes won't offer reduced stopping distances, barring fade considerations. I could be wrong, but I simply don't comprehend how that's possible.

Quick_lude

I would prefer steel braided brake lines and four piston calipers over largers rotors. And high temp brake fluid.

SpreeGuy

the difference is the abilty of the brake to lock the wheels at higher speeds. Try and lock the brakes going 10mph, or 100mph. With more powerful brakes you can slow down faster sooner

Sputnik

That's part of it.

The other part is the difference between making jerky, stabbing motions at the brake pedal (which will more likely lock the wheels up), and making smooth applications of the brake pedal. Just the mere fact that you can stab at the brakes at make them lock up is not an accurate test of a braking system's capabilities. It is possible to control them for better results, just like it is possible to control the throttle so that the rear tires don't break loose.

Of course, there is a point of diminishing returns, and the tire's ability is certainly a limiting factor. But there is normally room for some improvement. Whether you need it or not is the big question.

---jps