BRZ/86 stopping distance

[ZDan]

Originally Posted by Stonehorsw

BBK may help on bias, unsprung mass and response time.

Worth noting that installing a front BBK or overly conservative front/rear BBK system can *hurt* on bias.
For sure the "factory" BBK (PP Brembos) increase unsprung mass (I got aftermarket 2-piece rotors for the fronts to mitigate).
And some fixed-piston calipers (not the factory Brembos) have issues with pad kickback and you can end up getting zero pedal resistance and zero braking for a *disturbing* amount of pedal travel!

[Stonehorsw]

Originally Posted by Tcoat

All that you said just leads back to the brakes being better at letting the tire stop the car.
The point of the matter remains that just swapping out some bigger pads and rotors doesn’t mean you will stop quicker.

Yes
It can, but may not.

[Tcoat]

Originally Posted by Stonehorsw

Yes
It can, but may not.

All else being equal it will not.
What it will do for you is let you stop more often and at higher speeds without fade.

[Stonehorsw]

Originally Posted by ZDan

Worth noting that installing a front BBK or overly conservative front/rear BBK system can *hurt* on bias.
For sure the "factory" BBK (PP Brembos) increase unsprung mass (I got aftermarket 2-piece rotors for the fronts to mitigate).
And some fixed-piston calipers (not the factory Brembos) have issues with pad kickback and you can end up getting zero pedal resistance and zero braking for a *disturbing* amount of pedal travel!

Yes, and even worse with all the electronics installed that may get crazy. Even pad change may throw your electronics off.

Tires and suspension (geometry for reducing toe change, and damper adjustment to improve contact) are the ones that should be done first (geometry may not be possible in our case).

Did you see any improvement when going to 2-piece related to braking confidence level?

As you may have experienced, some of racing calipers require a pre-braking phase, where you blip the brake to make pads closer to the rotor before the braking zone. But I think this type of brakes should be used by professionals only, as you may get in trouble in the street.

[Stonehorsw]

Originally Posted by Tcoat

All else being equal it will not.
What it will do for you is let you stop more often and at higher speeds without fade.

You said that it will, at higher speeds
Less variance during braking also helps to shorten distance, as the driver input can be more precise (and proper feedback from system also helps)

Bur, as I mentioned, system response time may impct on that (the percentage may look negligible, and is for street applications, but may make a difference on race applications)

[Goingnowherefast]

Originally Posted by Tcoat

They are intended to combat fade not stop the car faster.

That is technically not true. Since this thread has already been necro'd we can talk about this. But basically every track pad comes with a high torque (mu) which will in fact stop the car faster given the tires stay adhered to the road.

[Tcoat]

Originally Posted by Goingnowherefast

That is technically not true. Since this thread has already been necro'd we can talk about this. But basically every track pad comes with a high torque (mu) which will in fact stop the car faster given the tires stay adhered to the road.

Bingo
It does not matter how fast you can stop the wheels turning if the tires just slide.

Everybody can try to play the technicalities all they want my simple statement was
"Brakes stop wheels. Tires stop cars"
All the braking power in the world has zero value if you don't have the grip to use it.

[Goingnowherefast]

Originally Posted by Tcoat

Bingo
It does not matter how fast you can stop the wheels turning if the tires just slide.

Everybody can try to play the technicalities all they want my simple statement was
"Brakes stop wheels. Tires stop cars"
All the braking power in the world has zero value if you don't have the grip to use it.

Originally Posted by Tcoat

As stated, the special compounds of performance pads and rotors is solely to combat heat from repeated and extreme braking maneuvers. They are intended to combat fade not stop the car faster.

Quoted again because it seems you forgot what you said. YOU said the special compounds of pads are solely to combat heat from repeated and extreme braking. That is demonstrably false, because we also know that performance pads come with higher torque which directly leads to lower stopping distances in performance applications when you are running performance tires.

No one is denying that tires aren't the most important factor here. Just pointing out that the claim you made is technically wrong.

[Stonehorsw]

Originally Posted by Tcoat

Bingo
It does not matter how fast you can stop the wheels turning if the tires just slide.

Everybody can try to play the technicalities all they want my simple statement was
"Brakes stop wheels. Tires stop cars"
All the braking power in the world has zero value if you don't have the grip to use it.

The tire road friction utilization is what stops the car. If you’re optimized for both front and rear, then you will reach the shortest braking distance.

[ZDan]

Originally Posted by Stonehorsw

Did you see any improvement when going to 2-piece related to braking confidence level?

I didn't expect to notice any difference and I didn't notice any difference! I was trying to get weight out of the car for time trials classification purposes and I highly prioritize weight off the front of the car. Li battery took off 24 lb., 2-piece rotors took off another 12. For ridiculous $$$/pound! But they also look neat :P

[Captain Snooze]

Originally Posted by Goingnowherefast

Quoted again because it seems you forgot what you said. YOU said the special compounds of pads are solely to combat heat from repeated and extreme braking. That is demonstrably false, because we also know that performance pads come with higher torque which directly leads to lower stopping distances in performance applications when you are running performance tires.
No one is denying that tires aren't the most important factor here. Just pointing out that the claim you made is technically wrong.

To expand on your statement you say "performance pads come with higher torque" but what you mean is "performance pads come with higher torque for a given applied force at the brake pedal." So regardless if you apply maximum torque to lock the brakes with a lot of pressure (average pads) or less pressure (performance pads) the torque is still the same at brake lock up. The point at which the wheel locks is determined by the grip of the tyres.

[Captain Snooze]

To repeat what has been said:

[Goingnowherefast]

Originally Posted by Captain Snooze

To expand on your statement you say "performance pads come with higher torque" but what you mean is "performance pads come with higher torque for a given applied force at the brake pedal." So regardless if you apply maximum torque to lock the brakes with a lot of pressure (average pads) or less pressure (performance pads) the torque is still the same at brake lock up. The point at which the wheel locks is determined by the grip of the tyres.

I genuinely don't think there's anyone in this thread that denies tires are the limiting factor to braking performance. We can probably move past that at this point, because we're beating a dead horse. Everyone understands that.

Higher mu pads at the same applied torque with tires that maintain grip will result in shorter stopping distances. Even if you have crappy tires velocity plays a function. Let's say you are traveling at 120 mph and you slam on the brakes, the force required to lock up the wheel at 120 mph is much greater than the force to lock up the wheel at 20 mph.

[Ultramaroon]

Originally Posted by Goingnowherefast

I genuinely don't think there's anyone in this thread that denies tires are the limiting factor to braking performance. We can probably move past that at this point, because we're beating a dead horse. Everyone understands that.

Higher mu pads at the same applied torque with tires that maintain grip will result in shorter stopping distances. Even if you have crappy tires velocity plays a function. Let's say you are traveling at 120 mph and you slam on the brakes, the force required to lock up the wheel at 120 mph is much greater than the force to lock up the wheel at 20 mph.

No. Mu is shorthand for frictional coefficient. Higher "mu" simply lowers the pedal force required to achieve the same reactive torque required to counteract the wheel torque, which is limited by tire grip - also with its own mu.

I'm not a tribology expert but I don't remember seeing a speed component affecting dynamic coefficient of friction in any of my related studies.