Argument for Bigger Brakes

[JZiggy]

Hey guys,

One of the favorite mods in the Toyota 4x4 world is to upgrade to larger front calipers for better braking performance. It is well understood that usually a larger master cylinder (MC) is needed to keep the hydraulic leverage ratio the same, and therefore preserve pedal feel. Some folks also upgrade the master cylinder booster from a single to dual diaphragm for more brake assist.

Forgetting the booster for now, here's where I'm getting hung up. If you assume that your input braking force is constant (i.e., how hard you can push with your foot times the leverage of the pedal), then increasing the size of the MC reduces the fluid pressure, and thereforce the force at the calipers. If you compensate with bigger calipers, then you can recover the force you lost. But it all comes down to the hydraulic leverage (ratio of areas of MC to slave cylinders).

The math doesn't seem to indicate that actual force at the calipers is increased by increasing the size of the MC and calipers together, assuming you preserve the hydraulic leverage ratio.

What is the motivation then for "upgrading" to a larger MC and larger calipers?

 

[dparm]

It depends what you mean by "larger calipers". I assume you mean the piston itself is bigger, or it has more pistons. You can squeeze harder/more evenly with those.

In some instances, there are lightweight calipers (monoblock) which reduce unsprung weight.

 

[bepperb]

There is a vacuum assist "brake booster" that you are disregarding. By varying the size of that the line pressure can remain constant but the system can service a larger (or more) caliper piston.

 

[Eddie]

+1.

 

[Jeffs2006EvoIX]

Upgrading brakes is usually always a good thing. There is a mathematical equation to decide what calipers go with what master cylinder and as stated that can be manipulated by different variables.

You dont want to go too big, that is for sure. In most cases, just upgrading the Lines, Fluid and Pads are all that are needed in most applications.

Jeff

 

[Cardenio327]

Before I spent a thin dime on modifying brake systems I would take a long hard look at tires.

A vehicle can brake no better than its tires allow it to, no matter how good or improved its brakes are.

Tires are the single aspect of your vehicle that most affect its braking ability and are easy and cheap to upgrade. Try moving up a quality, i.e. from Hankook to Goodyear, or upgrade from Goodyear to Michelin or Bridgestone. Generally speaking, the more respected a tire brand is, the better its braking characteristics are.

Changing types will greatly improve braking as well, if you can give up off road traction. All-terrains will brake better than mud tires, all-seasons better than all terrains, dedicated summer or winters better than all-seasons.

 

[dparm]

^ Correct. As soon as ABS engages or you lock the brakes, any additional braking capability cannot be used.

It's why I don't understand folks who spend money on big brake kits for a street driven car. Unless you are buying it purely for looks, it is doing NOTHING when you panic stop from 30mph in traffic. Sure, the unsprung weight might be a bit less, but are you really going to notice that when you drive to Taco Bell at 3am? The expensive pads and rotors will probably take a big piece of that Taco Bell budget, truth be told.

 

[SuperDave456]

Premium Tires, Premium Discs, Premium Pads typically beat changing things out, and is much cheaper in the long run.

 

[yonyon]

"Big Brakes" isn't necessarily about big calipers or more clamping. Big brakes can also be about bigger rotors with more mass and more surface area. More mass means it takes more heat to reach the same temperature and more surface means they can dissipate heat faster.

This shouldn't matter in "normal" service, but if your usage brings you into the land of brake fade it becomes worthwhile to get the rotors to run cooler. Disc size does matter.

 

[Smoky14]

Swept area is what you want to look for to increase brake efficiency.

 

[SteveSRT8]

Originally Posted By: SuperDave456
Premium Tires, Premium Discs, Premium Pads typically beat changing things out, and is much cheaper in the long run.


Many times the aftermarket can yield an improvement, but it can be difficult to separate the good stuff from the hype.

It should also be noted that many have installed various aftermarket parts on their braking setups and had significantly WORSE results.

 

[nleksan]

I have big (aka expensive) brakes on a couple of my cars, and while there is no question that there is a noticeable improvement in feel or modulation on the street, there is no performance benefits to be had until you are running tires that exceed the traction provided by all but the top 0.1 percent of extreme performance summer tires, which barely qualify as Street legal anyway.

On track, however, I have increased braking performance quite significantly.


Bottom line is that unless you are going to be spending 10+ days on the track every summer, you are simply payingffor bling.
It both amazes and aggravates me when I see "ricers" and their ilk w "big brake kits" underneath some $99 junk cast bricks, err, wheels, wrapped in whatever knockoff Chinese junk tires were the absolute cheapest at the time. I simply don't understand why you would spend thousands on premium brakes just to negate the possible benefits by increasing unsprung weight to where it's 10lbs more per corner, and the tires are barely able to hold themselves together....

 

[surfstar]

But they look cool when they're so shiny and full of holes behind some outrageously sized wheels. Who cares if the actual performance decreased vs stock.