Brake rotor temperature right/left and front/rear comparison questions

[CSG Mike]

Originally Posted by Gforce

Actually the mc needs a diaphragm type seal under the cap otherwise the piston would create a partial vacuum every time you tried to apply the brakes. Make no mistake, water contamination of brake fluid remains a problem. Car makers and brake system makers all recommend routine and regular flushing of brake fluid for this reason.

As for the performance of "race pads" equalling that of street pads under all conditions I will defer to your racing experience. Whether race pads are better for a road car then street pads is the issue I am discussing. On that metric race or track pads are dangerous, in my opinion. Brake pad makers agree. The first time you rear end someone would prove my point. However, most drivers will be unaware that they do so because of their track biased brake setup.

Thanks for the link but an understanding of high school physics is sufficiently sophisticated to understand braking systems. "Impulse" is not a helpful concept. The cause of brake overheating is simply the delta between heat creation and dissipation. The resulting net quantity is absorbed by the rotors. Conduction eventually raises the temperature of the brake fluid above its boiling point. The pads will continue to brake the car as long as the driver is able to apply sufficient line pressure. Unlike a drum brake which fades to nothing regardless of mc piston stroke, lining material or driver strength. That is the fundamental difference between real brake fade, as is still experienced by heavy truck drivers, and disc brake "fade" which rarely occurs in reality. Just recently I observed a Red Bull F1 car with a dragging left front brake resulting from overheating of the brakes, the mechanic was using a dry ice cooled blower to free up the caliper. Thermal expansion assists the driver using disc brakes.

If you do not understand impulse, you are not qualified to comment on any subject matter in this thread.

Impulse, is a high school physics topic. Brake systems are application of that high school level physics. Somewhere, there is a disconnect for you.

Heat is not magically generated instantly, and heat is not transmitted instantly. Think about that.

[Gforce]

Originally Posted by CSG Mike

If you do not understand impulse, you are not qualified to comment on any subject matter in this thread.

Impulse, is a high school physics topic. Brake systems are application of that high school level physics. Somewhere, there is a disconnect for you.

Heat is not magically generated instantly, and heat is not transmitted instantly. Think about that.

I understand "impulse". I'm pretty sure you don't need this concept to discuss brake overheating.

I'm pretty sure friction heat is created instantly. At least I hope my brakes do that. I am equally sure that brakes begin dissipating that heat instantly. That's how they work.

The problems presented by track driving are not encountered in street driving which is at least one reason why road &track magazine stopped testing for brake fade a very long time ago. They weren't getting any measurable fade from four wheel disc systems after six consecutive stops from 60 mph.

That's just one example.

Brake fluid doesn't boil in street driving unless the fluid is water contaminated. Although big improvements have been made in keeping ambient air and brake fluid separate the fluid still needs to be flushed regularly, at least every four years. My preference is every three years.

Disc brakes can easily dissipate heat resulting from even spirited street driving. The wheels on a street car just never get very hot, a clear indication that the brakes are working just fine.

For brake fluid to boil on a track the wheels would get too hot to touch.

[Gforce]

Originally Posted by wparsons

What makes the pedal go to the floor in a drum system if it isn't air in the lines (from boiling fluid)?

Expansion of the brake drum beyond the limit of the stroke of the wheel cylinder.

The single advantage of disc brakes when first introduced into racing cars was that the brakes never "failed". They might require higher line pressure as they got hotter but they never disappeared entirely. Drum brakes could fade to zero braking force. This is an important difference.

Drum brakes are actually still adequate for rear brakes on street cars, not so front brakes.

Four wheel discs are now standardized for economic reasons, production costs are comparable but rear drums are now too expensive to service.

[HappyMonkey]

Originally Posted by OND

AFAIK Stoptech pads are still too much street oriented, so you might have some fade with them. The thread is kind of hard to follow, but which brake fluid are you running again?

I started out with Project Mu HC+ and Motul RBF600 and I think it is a pretty good setup to begin with.

So it's looking like every initial decision I made was significantly suboptimal. Throwing money away is one way to learn...

From what I've been reading the Hawk High Performance Street Race pads are a little more street friendly than the Project Mu HC+ 800 ones. Leaning toward the Hawk until I swap out dedicated track pads.

For fluid I'm using ATE Typ200. No idea how I decided on it. Sounds like everyone uses Motul RBF600. I might as well join the club too.

[HappyMonkey]

Originally Posted by churchx

BTW, is that stoptech BBK or just few stoptech aftermarket parts for stock replacement? In former case i'd use on track that BBK, due higher thermal capacity & possibly cheaper wearables & lighter weight & easier to swap pads. In later case .. i'd keep those lines/pads .. but probably switch back drilled-slotted rotors to stock.

They're the StopTech replacement rotors not a BBK. I think I'm going to put the stock ones back on. A rotor swap doesn't take that long and I'm getting better pads and probably fluid anyway.

Instead of thinking of my drilled ones as money lost I'll reframe it as a successful introduction to doing more maintenance work myself and a massive learning opportunity. Because otherwise, ...

[HappyMonkey]

Originally Posted by cjd

The stock are summer tires, not all season... But are low rolling resistance so I could see better feel from good all seasons... Unsure about lap times, assuming you're consistent.

Tires, brakes, brake fluid... Temperature management is the issue. If you're driving 10/10 you'll run short on overheated pads with the street compounds, but may hit fluid boiling first being on the brakes longer (tires and eventually brake compound contributing to longer stopping distance). Watch the tires for bad behavior too. Keep a close eye on those drilled rotors for cracking. At least bring blanks as backup.

She'll be on Yokohama Advan Neova AD08 tires this week. I actually need the all season ones in the winter and I don't want to wear them down on the track.

This thread has convinced me to go back to stock rotors. My rotors can look cool when I get a BBK but not until then.

[OND]

Originally Posted by HappyMonkey

So it's looking like every initial decision I made was significantly suboptimal. Throwing money away is one way to learn...

From what I've been reading the Hawk High Performance Street Race pads are a little more street friendly than the Project Mu HC+ 800 ones. Leaning toward the Hawk until I swap out dedicated track pads.

For fluid I'm using ATE Typ200. No idea how I decided on it. Sounds like everyone uses Motul RBF600. I might as well join the club too.

Sounds good, i havent tried, but there are lots of people happy with ATE too.

[CSG David]

Originally Posted by OND

Sounds good, i havent tried, but there are lots of people happy with ATE too.

If everyone in your community struggles to put heat into their systems, then it's understandable that the concept of RBF600 and Super ATE are going to be sufficient for your use. It is definitely one of the better ideas to use compare to OEM or standard DOT3 brake fluid for track use though.

[CSG David]

Originally Posted by cjd

The stock are summer tires, not all season... But are low rolling resistance so I could see better feel from good all seasons... Unsure about lap times, assuming you're consistent.

Tires, brakes, brake fluid... Temperature management is the issue. If you're driving 10/10 you'll run short on overheated pads with the street compounds, but may hit fluid boiling first being on the brakes longer (tires and eventually brake compound contributing to longer stopping distance). Watch the tires for bad behavior too. Keep a close eye on those drilled rotors for cracking. At least bring blanks as backup.

Temperature management is more important than anything. If a capacity is reached on some component, then that is the limitation. Improving each category adds additional capacity and elevates the total "average" of the complete system. Your understanding has improved significantly since we first chatted over PM @cjd.

Originally Posted by HappyMonkey

She'll be on Yokohama Advan Neova AD08 tires this week. I actually need the all season ones in the winter and I don't want to wear them down on the track.

This thread has convinced me to go back to stock rotors. My rotors can look cool when I get a BBK but not until then.

Many people who can afford it will have two sets of wheels for different purposes. Many people do not understand the idea of drilled, slotted, J-hook, silly lines, and hello kitty grooves. If you don't understand it and why it actually may help you out, then blank discs are best.

Disclaimer: Not all blank discs are created equal.

[OND]

Originally Posted by CSG David

If everyone in your community struggles to put heat into their systems, then it's understandable that the concept of RBF600 and Super ATE are going to be sufficient for your use. It is definitely one of the better ideas to use compare to OEM or standard DOT3 brake fluid for track use though.

To clarify, I don't know anyone using ATE first hand. I just saw that mentioned a lot when I was searching for fluids online and some people seemed really happy with it even though the specs arent that impressive.

A couple of us use RBF600 at our local track without issues, but our local track is pretty "flowy", so it's probably not too hard on the brakes to begin with.

[CSG David]

Originally Posted by OND

To clarify, I don't know anyone using ATE first hand. I just saw that mentioned a lot when I was searching for fluids online and some people seemed really happy with it even though the specs arent that impressive.

A couple of us use RBF600 at our local track without issues, but our local track is pretty "flowy", so it's probably not too hard on the brakes to begin with.

Living near COTA must be a dream, but it's also a medusa if you're not prepared. Send me a PM if you want to discuss brakes and how to setup for your specific application and courses.

[OND]

Originally Posted by CSG David

Living near COTA must be a dream, but it's also a medusa if you're not prepared. Send me a PM if you want to discuss brakes and how to setup for your specific application and courses.

Lol I actually forgot COTA was an option I can't imagine that place being easy on the engine or the brakes. Plus that loooong back straight in a momentum car...

I visit Harris Hill Raceway, which is a much smaller track and not that hard on consumables.

[CSG David]

Originally Posted by OND

Lol I actually forgot COTA was an option I can't imagine that place being easy on the engine or the brakes. Plus that loooong back straight in a momentum car...

I visit Harris Hill Raceway, which is a much smaller track and not that hard on consumables.

People often forget that all cars are "momentum" cars.

[CSG Mike]

Originally Posted by Gforce

I understand "impulse". I'm pretty sure you don't need this concept to discuss brake overheating.

I'm pretty sure friction heat is created instantly. At least I hope my brakes do that. I am equally sure that brakes begin dissipating that heat instantly. That's how they work.

The problems presented by track driving are not encountered in street driving which is at least one reason why road &track magazine stopped testing for brake fade a very long time ago. They weren't getting any measurable fade from four wheel disc systems after six consecutive stops from 60 mph.

That's just one example.

Brake fluid doesn't boil in street driving unless the fluid is water contaminated. Although big improvements have been made in keeping ambient air and brake fluid separate the fluid still needs to be flushed regularly, at least every four years. My preference is every three years.

Disc brakes can easily dissipate heat resulting from even spirited street driving. The wheels on a street car just never get very hot, a clear indication that the brakes are working just fine.

For brake fluid to boil on a track the wheels would get too hot to touch.

Go try this in your car and tell me what happens.

Magazines stopped doing it because they were destroying cars given to them for journalistic review, and were pissing off manufacturers.