Bigger brakes fro the street - worth it or not?

Hello everybody,,

This is more of a theoretical question right now, as I am not working on anything right now, But.... I always assumed that bigger rotors and larger calipers added more stopping power not just better heat dissipation. My thought process was that a larger rotor with more surface area and more pad area would give you more friction to slow the car down. I am asking in reference to say coming around a corner and seeing an accident and having to stop quickly, or say a deer running out into the road. So all things being equal, tires, pads, wheel size, etc. Also without locking up the tires.

However I have been told I am wrong, that all things being equal as long as you can lock up the tires with a stock system larger brakes don't stop you faster. That it is all about tire to road and more pad friction doesn't help. This seems counter intuitive to me. Am I wrong?

(again, all things being equal and not locking up the brakes but modulating the pedal so you don't, but still stopping in as short a distance as possible in a cold one time stop). Thanks.

See this post for the "lock up the brakes means you have enough power"  Granted this is on a car I vintage race. https://grassrootsmotorsports.com/forum/grm/lets-discuss-the-if-you-can-lock-the-wheels-the-br/143113/page1/

First you are not wrong or not completely wrong. As you will see from the linked post I dislike the blanket statement about "locking up the wheels"

The tires only have so much traction but what bigger brakes may do is allow you to get to the threshold faster and modulate the brakes easier, allowing you to get maximum braking for the entire stopping distance.

I said may becuase it's going to be car dependent; a shiny new 911 isn't likely going to benefit from larger brakes on it. On the other hand your Corolla or Sentra will, especially at highway speeds.

I will give you a pratical example; my 2011 Outback has decent brakes but when you brake really hard it's obvious it could do with better brakes. I suspect that in a 70 mph to 0 mph stop that there is 5-10ft shorter distance to be had. Not a lot but maybe just enough to matter

The reality though is that simply putting sticky tires on the car would likely net a bigger result. 

In the age of ABS bigger brakes on a street car likely aren't worth doing but again they could be.

There are some cars that need bigger brakes because the factory provided gear is deficient. Examples - the old (not BMW) Mini Coopers with a band of rotor about 2" wide, living inside a 10" wheel, and the Sunbeam Tiger, - put V8 in car with 13" wheels which limit possible brake size and cooling = foreseeable disaster.

But most cars are perfectly adequate with factory equipment IF they are in prefect shape, and have properly chosen fluid and pad compounds.

I see these discussions all the time on the boards where people stick V8 engines into MGBs and then claim that you need bigger brakes. But there is no added weight, or nothing significant and these street drivers would have to be driving at highly illegal speeds or racing down a mountain to stress the stock braking system, which is perfectly capable of stopping an SCCA racer on the track from well over 100 mph, lap after lap without fade.

I think that 90% of the big brake upgrades performed out there are for macho bragging rights, not actual necessity.

Just how capable the factory set up on a given car may be is situational - but by far the largest proportion of stock cars built withing the last few decades are well served by stock equipment.

Tom's comments are well founded, though, as manufacturers can spec adequate systems capable of shedding all the kinetic energy you can conceivably convert to heat on the street, but still make poor choices regarding front rear proportioning, overall servo assist etc. which make them a bit of a pig to drive really hard. A change in cylinder size or a proportioning valve or balance bar can usually improve that sort of thing.

I removed a spam link from the original post, but if there's a discussion to be had, I'll leave the thread be.