19 SILVERADO FRONT BRAKE UPGRADE

[truckmann]

25 minutes ago, truckguy82 said:

You are wrong about the lever effect.

 

Think about bicycle disc brakes vs Traditional cantilever brakes. The disc brakes are all the way center and work even better

He's not wrong at all. You are comparing 2 completely different types of breaking systems on a bicycle. That's like comparing apples to tomatoes. It's like comparing manual drum brakes to modern power disc brakes. The disc brakes take advantage of hydraulic power and better friction material so they can be smaller. The cantilever style are actuated by a cable and have lesser friction material which means they need to be on the outside diameter of the wheel to have a chance. 

 

Given 2 different disc brake systems on a bicycle with the only difference being rotor size the larger rotor will be better. 

 

https://www.bikeradar.com/advice/buyers-guides/buyers-guide-to-mountain-bike-disc-brakes/

 

"Power varies with each caliper and its pad surface/leverage, but the biggest difference is rotor size. The bigger the rotor, the more leverage your brake has on the wheel and the faster it can stop it. Each 20mm increase in size roughly equates to a 13 to 15 percent increase in power."

Edited February 23, 2020 by truckmann

[truckguy82]

49 minutes ago, truckmann said:

He's not wrong at all. You are comparing 2 completely different types of breaking systems on a bicycle. That's like comparing apples to tomatoes. It's like comparing manual drum brakes to modern power disc brakes. The disc brakes take advantage of hydraulic power and better friction material so they can be smaller. The cantilever style are actuated by a cable and have lesser friction material which means they need to be on the outside diameter of the wheel to have a chance. 

 

Given 2 different disc brake systems on a bicycle with the only difference being rotor size the larger rotor will be better. 

 

https://www.bikeradar.com/advice/buyers-guides/buyers-guide-to-mountain-bike-disc-brakes/

 

"Power varies with each caliper and its pad surface/leverage, but the biggest difference is rotor size. The bigger the rotor, the more leverage your brake has on the wheel and the faster it can stop it. Each 20mm increase in size roughly equates to a 13 to 15 percent increase in power."

And yet when you increase the diameter by 10x (putting them on the outside) they are suddenly weaker

 

you don’t understand the physics of using a friction surface to stop something.

 

why on earth would they move the brakes to the inside if the larger diameter has increased braking power? 
 

This is a common misconception that some intelligent people don’t understand. Including You and bike radar. And including myself until I got schooled by someone that actually engineers brakes.

 

brake rotor diameter has nothing to do with increase mechanical advantage. I realize you’re all picturing a 6” long wrench and a 12” long wrench in your head.

 

i promise you are wrong

[truckguy82]

The only advantage to larger brakes is increased heat capacity and increased dissipation of heat. 
 

How much force the pad needs to apply to the rotor is not relevant

[truckmann]

Well I am 100% positive you are wrong but I guess no amount of logic or source material will prove that to you so I won't bother to try. 

[davester]

2 hours ago, truckguy82 said:

You are wrong about the lever effect.

 

Think about bicycle disc brakes vs Traditional cantilever brakes. The disc brakes are all the way center and work even better

No, he's not.  Your bicycle example is comparing different braking systems, with different brake material, size of shoes on the braking surface, and even the braking surface itself.

 

Take some mechanical engineering courses, or even just think about it more, and you'll understand that for the same clamping force on the disc brake, if it is applied on a larger disc, there is more braking force applied to the wheel.

[truckguy82]

2 hours ago, davester said:

No, he's not.  Your bicycle example is comparing different braking systems, with different brake material, size of shoes on the braking surface, and even the braking surface itself.

 

Take some mechanical engineering courses, or even just think about it more, and you'll understand that for the same clamping force on the disc brake, if it is applied on a larger disc, there is more braking force applied to the wheel.

Lol

 

i understand more clamping force is required

 

clamping force is irrelevant

 

you should take some engineering courses

[truckguy82]

3 hours ago, truckmann said:

Well I am 100% positive you are wrong but I guess no amount of logic or source material will prove that to you so I won't bother to try. 

Nope because I said the same thing you’re saying now, and then I got schooled

 

i dont have the time right now to take you to brake school but I can if you want on a week day

[truckguy82]

I guess the key to understanding this is that clamping force is not important.

 

all that matters is total energy converted to heat

[truckmann]

The thing is I understand physics very well and yes it is about the heat conversion, but I think what you are missing is that keeping the same amount of clamping force and pad surface area (basically saying that all things are equal) a larger rotor will create a larger torque force to stop the rotation. Even the equation to calculate brake torque requires the radius of caliper. On top of that a larger rotor is also moving faster through the pads thus creating more heat friction. I could link to many articles that explain it and I don't think I can find a single one that would argue that larger rotors don't allow for a larger brake torque.  Also even though the rotor is the main heat dissipating feature in the system that is not it's main mechanical function. The reason good heat dissipation is needed is to keep from overheating all the components of the system like not warping the rotors and boiling the brake fluid. 

 

Here's an article from an engineering company that says it very simplistically. 

http://www.wcengineering.com/articles/brakes.html

 

and here's a white paper from a well know brake manufacturer with formulas. 

https://www.apcautotech.com/getmedia/89aa6773-73d7-4f7f-b935-5e6bf2d28111/Centric_and_APC_Technical_Whitepaper_A1-The-Physics-of-Braking-Systems-8-2018_1.pdf

 

As for this having any bearing on the upgrade to the 19/20 brakes it's probably not a big factor since the new rotors are not much bigger than the stock 14-18 rotors. The big improvement is with a more even clamping force from the 4 piston calipers and an increased pad contact area. Possibly a better pad friction material and difference in over all piston area too, but I can only speculate about that. 

 

I actually look forward to see what you have to say that could explain how rotor diameter has no effect on brake torque stopping power. 

 

 

[flyingfool]

you can get 60-0 mph stopping specs from "car and driver" magazine at your local library....  

i've seen real world test on two mercedes benz sedans, one with the stock base model brakes, and then the same car with big AMG monster brakes... my discovery was the Base model 320 car out performed the AMG-32 car  by stopping 12-15 foot shorter braking distance from 60--0 mph.  but the AMG32  will have more fade resistance durring hard driving, where as the  base car only has about 5 good hard stops left in it before fade is excessive

 

Edited February 24, 2020 by flyingfool

[truckmann]

22 minutes ago, flyingfool said:

you can get 60-0 mph stopping specs from "car and driver" magazine at your local library....  

i've seen real world test on two mercedes benz sedans, one with the stock base model brakes, and then the same car with big AMG monster brakes... my discovery was the Base model 320 car out performed the AMG-32 car  by stopping 12-15 foot shorter braking distance from 60--0 mph.  but the AMG32  will have more fade resistance durring hard driving, where as the  base car only has about 5 good hard stops left in it before fade is excessive

 

I believe that. There's more going on there than just rotor size though. They are 2 systems purposely built for different situations. Everyday street car brakes built to stop as short as possible but not very many times while a track focused car built to handle multiple heat cycles and continue to work. Initial grab and continued usage is more important than getting to 0 on a track car. Without trying to look it up I'd bet they have different pad material and possibly different rotor material. So not really an apples to apples comparison. 

[groovy_moon]

On 2/22/2020 at 4:44 PM, lovelessjl said:

So is the old wisdom style of bedding the pads (basically several aggressive brake applications til almost stopped) still effective and worthwhile? Or is that just one of those "we've always done it this way" kind of things?

Sent from my SM-N950U using Tapatalk
 

"Bedding In" is best done with easy driving for about 50 stops or so. When we "burnish" pads for testing we make 200 stops from about 50 mph to 0 at about 0.3 g every ~1-1.5 miles. This is a little bit more aggressive than what you would do approaching a stop sign. The most important thing is not to get them really hot when they are new. Some heavy duty linings like the kind found on Camaro SS's or Mustang GT's with the Brembo package can take longer to achieve a stable friction level.

 

[groovy_moon]

14 hours ago, truckmann said:

I believe that. There's more going on there than just rotor size though. They are 2 systems purposely built for different situations. Everyday street car brakes built to stop as short as possible but not very many times while a track focused car built to handle multiple heat cycles and continue to work. Initial grab and continued usage is more important than getting to 0 on a track car. Without trying to look it up I'd bet they have different pad material and possibly different rotor material. So not really an apples to apples comparison. 

The friction material may have a big part in that. Some high performance linings do not achieve max friction until they get very hot.

 

[groovy_moon]

18 hours ago, truckmann said:

The thing is I understand physics very well and yes it is about the heat conversion, but I think what you are missing is that keeping the same amount of clamping force and pad surface area (basically saying that all things are equal) a larger rotor will create a larger torque force to stop the rotation. Even the equation to calculate brake torque requires the radius of caliper. On top of that a larger rotor is also moving faster through the pads thus creating more heat friction. I could link to many articles that explain it and I don't think I can find a single one that would argue that larger rotors don't allow for a larger brake torque.  Also even though the rotor is the main heat dissipating feature in the system that is not it's main mechanical function. The reason good heat dissipation is needed is to keep from overheating all the components of the system like not warping the rotors and boiling the brake fluid. 

 

Here's an article from an engineering company that says it very simplistically. 

http://www.wcengineering.com/articles/brakes.html

 

and here's a white paper from a well know brake manufacturer with formulas. 

https://www.apcautotech.com/getmedia/89aa6773-73d7-4f7f-b935-5e6bf2d28111/Centric_and_APC_Technical_Whitepaper_A1-The-Physics-of-Braking-Systems-8-2018_1.pdf

 

As for this having any bearing on the upgrade to the 19/20 brakes it's probably not a big factor since the new rotors are not much bigger than the stock 14-18 rotors. The big improvement is with a more even clamping force from the 4 piston calipers and an increased pad contact area. Possibly a better pad friction material and difference in over all piston area too, but I can only speculate about that. 

 

I actually look forward to see what you have to say that could explain how rotor diameter has no effect on brake torque stopping power. 

 

 

IMHO one of the big differences is in the friction level of the pads. HH is really high for a pass car lt truck lining. 

The fixed caliper adds to the stiffness.. I need to understand the piston diameter of the pre 2019 calipers to make a comparison there. It is possible that the surface area f the 2019-2020 fixed calipers is smaller with the increased friction making up for it.... this would also add to the stiffer feeling

https://idpartsblog.com/2019/04/11/what-do-brake-pad-friction-ratings-mean/

 

Several of the Engineers I wor with have Pre 2019 GM trucks and most are going to do this..

I have an ex GM Executive lease 2019 Suburban we just picked up with the floating calipers and vacuum booster (same as 2018 and earlier trucks). This weekend I had my family and gear for a ski weekend ~800 lbs and the brakes do suck. So I am looking into it for the 'burb.

 

[groovy_moon]

8 minutes ago, groovy_moon said:

 

Didn't read the whole article but I think they forgot about the booster's multiplicative and additive effects on the input to the master cylinder.. This is defined by the "jump in" of the booster and the "servo ratio" of the booster.

 

The JumpIn is an initial bump up of the output force of the booster when the pedal is initially depressed (a few mm).

The servo ratio is the multiplier of the booster on the input force from the pedal.... so the output of the booster approximately is:

Output Force = (Input Force X Servo Ratio) + JumpIn

Servo Ratio is usually in effect until input force on the brake pedal is about 200 N.

 

That force is then imparted to the master cylinder pistons.

 

Edited February 24, 2020 by groovy_moon