Rotors look small

[Razorback]

that's one of the first things I'll be looking to upgrade, to be honest. getting rid of the stock rubber brake lines and upgrading to SS braided lines with high temp fluid.

Saved in my to do file...

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[vrtical]

I have 352mm on the front of one of my cars lol

 

[AcesandEights]

Looks to me like it has large six lug hubs that make the rotor diameter look small. You don't need big rotor faces if they are large diameter. The clamping and friction force being applied at a larger radius will give you more braking force. If you were going to make laps around a road track as fast as possible non-stop, you might want more rotor so you don't melt them down. I doubt the bronco is being designed/tested for high speed, long term, road track racing.

I think trail driving, crawling, would be much harder on the braking system than driving around a track. High speed probably wouldn't be an issue, but crawling might.

 

[nd2002]

I think trail driving, crawling, would be much harder on the braking system than driving around a track. High speed probably wouldn't be an issue, but crawling might.

You’re telling me dragging brakes at 5mph will make the rotors glow red?

 

[L8apex]

I'm not arguing that the rear brakes don't do anything, but we shouldn't be "skimping" on rotor size front or rear.

Agreed I was more so addressing the other posters initial claims that rear brakes are for show.

If we are all purchasing an off road beast, a Sasquatch, we should have oversized rotors designed for high-heat and long runs with people riding the brakes. That's the real world situation people expect from the vehicle, and of course the 60mph to zero.

If people are going long runs and riding the brakes, I 70 around Eisenhower tunnel for example, then yes they can expect some level of brake fade. Even if they had larger brakes / calipers - unless they're upgrading to full carbon-ceramic rotors and pads there will be some level of fade.

But most grades you do at HWY speed in the US you can minimize braking with engine braking.

 

[AcesandEights]

You’re telling me dragging brakes at 5mph will make the rotors glow red?

Sure. I think people 4wheel at various speeds, but 5mph for a long enough distance will certainly do that. Do a search. First one that popped up for me was a guy using 13" rotors and having trouble stopping in 4low. Suggestion was to pop it into neutral, because of the torque multiplication in 4low. One of the first questions was what's your crawl ratio. Believe it or not, it's a thing.

 

[AcesandEights]

@L8apex That's my point, there will be fade. There will be. Better brakes are better.

 

[wjfawb0 [hacked account]]

Heat in the rotors will be proportional to the work done slowing or stopping the vehicle. Riding the brakes while crawling isn't going to make the heat that slowing from 100-50mph repeatedly will produce. If a driver with a manual is heating up the brakes because they're riding them, that's on the driver. If an automatic's torque converter stays locked when the driver is standing on the brakes in 4LO, that's bad programming on the manufacturer's part.

 

[Gamecock]

I think trail driving, crawling, would be much harder on the braking system than driving around a track.

Driving around a race track fast and braking into corners....Not even close....WAY more on the brakes doing that than trails/crawling. Not in the same universe.

 

[nd2002]

Heat in the rotors will be proportional to the work done slowing or stopping the vehicle. Riding the brakes while crawling isn't going to make the heat that slowing from 100-50mph repeatedly will produce. If a driver with a manual is heating up the brakes because they're riding them, that's on the driver. If an automatic's torque converter stays locked when the driver is standing on the brakes in 4LO, that's bad programming on the manufacturer's part.

This. Brakes are converting kinetic energy of your moving vehicle to heat. KE = 1/2 mv^2, so the weight of the vehicle and speed will primarily determine the amount of this energy that needs to be converted to heat. Pads and fluid are other factors when considering how fast this energy is converted to heat, but with a tiny "v," I find it hard to see the argument for needing more rotor surface area.

Certainly not trying to say it's pointless having upgraded brakes, but for the use case for the Bronco, it seems that the stock brakes should work just fine for any scenario, including emergency stopping or going down an incline at a low speed.

 

[AcesandEights]

So size of the tire has no impact on braking, since it is speed of the object in motion and mass of the object (the vehicle, the Bronco versus the object rotating, the tire)? Does the size of the tire impact the amount of torque applied to the brakes?

Is the motor also creating motion, through torque, that travels through the drivetrain, multiplying, and impacting the speed or mass (force or linear motion) that is modulated through the braking system?

These are questions, not statements by the way. Maybe all of the answers are no, and both tire size and crawl ratio have no impact on braking. That's not my experience.

 

[kodiakisland]

Well that is simply not true.

My rear drums with no measurable wear on the shoes after 120K miles beg to differ.

 

[jjack50]

My rear drums with no measurable wear on the shoes after 120K miles beg to differ.

If that’s the case, then your brakes are not balanced properly. There should be automatic proportioning of braking force between the front and the rear brakes in order to keep the braking forces in balance. Too much at either end when hard braking usually leads to directional control problems.

If your rear brakes are not being used at all it means you aren’t stopping as well as you could be.

 

[kodiakisland]

If that’s the case, then your brakes are not balanced properly. There should be automatic proportioning of braking force between the front and the rear brakes in order to keep the braking forces in balance. Too much at either end when hard braking usually leads to directional control problems.

If your rear brakes are not being used at all it means you aren’t stopping as well as you could be.

No, they are correctly set up. For Toyota, rear brakes are an afterthought. But, at 120K my front pads aren't even worn half way down either, but rear brakes suck on Toyotas even under ideal setup. Who else still puts drums on $50K vehicles in 2021?

 

[L8apex]

No, they are correctly set up. For Toyota, rear brakes are an afterthought. But, at 120K my front pads aren't even worn half way down either, but rear brakes suck on Toyotas even under ideal setup. Who else still puts drums on $50K vehicles in 2021?

If at 120K your rear brakes were doing NOTHING, then your front pads wouldn’t be at >50%. Unless Toyota’s brake supplier, who supplies everyone else, has given them exclusive brake technology.

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