Mazda 6 Forums banner

1 - 20 of 25 Posts

·
Banned
Joined
·
351 Posts
Discussion Starter #1

·
Super Moderator
Joined
·
16,781 Posts
Mmmmmmm, now I almost WANT my stock brakes to need to be replaced lol. Still going to wait for that though.
 

·
Registered
Joined
·
1,000 Posts
I know that going down hills our cars could take advantage of the drilled rotors :)
 

·
Registered
Joined
·
26 Posts
if only this car had the power so it could utilize drilled/slotted rotors. They look cool though.
Drilled rotors will not do anything to improve braking performance. They are for looks, plain and simple. Drilled rotors are also more prone to cracking than non-drilled rotors. That’s not to be confused with auto manufacturers that offer rotors with cast holes on their performance cars, which is a completely difference process than these companies offering "cross drilled" rotors. Slotted rotors are fine and look good, but they don't really offer any other benefit over blank rotors with modern brake pads.

If you want to buy cross drilled rotors for looks, do so by all means. I just don’t want anyone to be duped into thinking they will improve performance. Notice that the company “Chromebrakes” makes no claims about improving braking performance by adding just these rotors.

The characteristics of a rotor that will improve performance are thickness (strength), vanes (venting/cooling), size (brake pad surface area, cooling), weight, material type, etc. The two biggest things you could do to improve braking on our cars are brake pads (better bite, less fade) and better brake fluid (stays cooler, less fade), and possibly stainless steel brake lines.

For those that want to learn more about drilled/slotted rotors, cracking, & cast holes, you can find info here:

Dangerous cross drilled rotors - EBC Brakes

Cross drilled rotor myths dissolved - 8th Generation Honda Civic Forum

If cross drilled rotors are bad how come high end cars have them - evolutionm.net
 

·
Registered
Joined
·
1,900 Posts
The two biggest things you could do ove braking on our cars are brake pads (better bite, less fade) and better brake fluid (stays cooler, less fade), and possibly stainless steel brake lines.
Thanks for pointing those out.

I was advocating for one...better brake fluid (it is a form of modification), but most in this thread I started take it for granted (it is our car's brakes, after all).

http://forum.mazda6club.com/mazda-6-3rd-generation-2013-present/307409-ate-super-blue-racing-dot4-flush.html
 

·
Registered
Joined
·
1,000 Posts
On that note, anyone buy aftermarket brake pads yet?
 

·
Banned
Joined
·
351 Posts
Discussion Starter #10
Mmmmmmm, now I almost WANT my stock brakes to need to be replaced lol. Still going to wait for that though.
same here:lol:
 

·
Banned
Joined
·
351 Posts
Discussion Starter #11
Drilled rotors will not do anything to improve braking performance. They are for looks, plain and simple.
What the hell????? Drilled rotors improve cooling, meaning less braking degradation with repeated use. This very well qualifies as an IMPROVED braking performance

Drilled rotors are also more prone to cracking than non-drilled rotors.
Generally true. $129.95 for 4 cross-drilled discs is a risky idea.

That’s not to be confused with auto manufacturers that offer rotors with cast holes on their performance cars, which is a completely difference process than these companies offering "cross drilled" rotors. Slotted rotors are fine and look good, but they don't really offer any other benefit over blank rotors with modern brake pads.
Disc Italia have cast holes. And I'm sure chromebrakes is adequately engineered not to crack too.
Slotted rotors help in wet conditions, but I guess you are right - the benefit in street use is dubious

The characteristics of a rotor that will improve performance are thickness (strength), vanes (venting/cooling), size (brake pad surface area, cooling), weight, material type, etc. The two biggest things you could do to improve braking on our cars are brake pads (better bite, less fade) and better brake fluid (stays cooler, less fade), and possibly stainless steel brake lines.
no need to upgrade brake fluid, unless the car intensely track-raced. Cross-drilling will do much more for cooling ACTUAL brakes. brake-fluid does not cool brakes. I agree regarding pads and everything else, save the brake lines, as the brake-fluid is a trivial component, unless the car is intensely track-raced.


^^ good stuff, thanks!
 

·
Registered
Joined
·
782 Posts
Wish someone made a big brake kit for the new 6, though it would require changing the stock mounting point of the calipers. The rotors are tiny, especially contrasted with the 19" wheels.

...Better yet, I wish Mazda would come up with a Speed 6 with bigger rotors and calipers, and that owners of the normal 6 could retrofit them fairly easily. :)
 

·
Banned
Joined
·
351 Posts
Discussion Starter #14

·
Registered
Joined
·
26 Posts
What the hell????? Drilled rotors improve cooling, meaning less braking degradation with repeated use. This very well qualifies as an IMPROVED braking performance
Wrong. Drilled rotors can actually create more heat as the braking surface where the pad contacts the rotor is decreased. The pad transfers heat into the rotor. A blank rotor has more surface area that can absorb and dissipate heat than a cross drilled rotor which has less surface area due to the holes. Larger contact surface = cooler. From Wilwood: Drilling diminishes a rotor's durability and cooling capacity.

Can you name one professional race series that currently uses drilled rotors? Formula 1, NASCAR, Indy Car, ALMS/Le Mans, Australian V8 Supercars, and WTCC cars do not use drilled rotors. If there was any benefit or improved performance, you would see them used in at least a few of these race series.

I've been involved in the racing community for almost 10 years now. I'll say it again, cross drilled rotors are for looks. If you read the thread on 8thcivic.com, you'll see why. Brake companies like StopTech, Baer, and Wilwood all recommend slotted rotors over drilled rotors for brakes that will actually be used. Drilled rotors are sometimes available from these companies for the people interested in looks, and some say the only benefit is less unsprung weight.

Generally true. $129.95 for 4 cross-drilled discs is a risky idea.
:thumbup:

Disc Italia have cast holes. And I'm sure chromebrakes is adequately engineered not to crack too.
Slotted rotors help in wet conditions, but I guess you are right - the benefit in street use is dubious
Where does it say Disc Italia casts the holes into their rotors? I'm no engineer, but their marketing material claims their rotors are cast, and the holes are bi-chamfered in. While this method is probably much better than cheapo ebay drilled rotors, they are not the same as holes cast in the rotors. If someone wants to spend $300 for drilled front rotors made by Disc Italia, that's fine by me. But they should understand they are paying $300 for improved looks and zero (maybe even negative) performance.

As for Chromebrakes... I certainly would not trust a brake company with 'chrome' in their name, and that offers blue and red rotors, to provide quality R&D'd products that improve performance. Maybe that's just me :confused:

no need to upgrade brake fluid, unless the car intensely track-raced. Cross-drilling will do much more for cooling ACTUAL brakes. brake-fluid does not cool brakes. I agree regarding pads and everything else, save the brake lines, as the brake-fluid is a trivial component, unless the car is intensely track-raced.
If you want to cool the actual brakes, you'll need brake ducting. Obviously not necessary for a street car, but cross drilled rotors simply will not cool your brakes off as I mentioned earlier. I am personally fine with the factory braking system, but for people that believe they need to improve braking performance (it doesn't matter to me if it's for track, autocross, canyon running, etc), all I'm saying is start with pads, then fluid, then brake lines. It is possible to reach the limits of OEM brake fluid on the street during very spirited driving. If the fluid boils, air will be in the lines/calipers and the pedal and braking force will become softer. A synthetic DOT4 fluid can help with as they have higher boiling points. The brakes are a system, and if your fluid, lines, master cylinder, calipers, or any other braking component is a weak point, your braking system as a whole will suffer.

Final thoughts on cross drilled rotors:

Here are some quotes from brake engineers, brake manufacturers, and automotive publications in regard to cross-drilled, slotted, and plain rotors.

AP Racing:
"Grooves improve 'cleaning' of the pad surfaces and result in a more consistent brake performance. Grooved discs have a longer life than cross-drilled discs."

Baer:
"What are the benefits to Crossdrilling, Slotting, and Zinc-Washing my rotors? In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads...However, with today's race pad technology, 'outgassing' is no longer much of a concern...Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer's offerings."

Darrick Dong; Director of Motorsports at Performance Friction:
"Anyone that tells you that drilling makes the disc run cooler is smoking crack."

Waren Gilliand:
(Warren Gilliland is a well-known brake engineer in the racing industry and has more than 32 years experience in custom designing brake systems ...he became the main source for improving the brake systems on a variety of different race vehicles from midgets to NASCAR Winston Cup cars.) "If you cross drill one of these vented rotors, you are creating a stress riser that will encourage the rotor to crack right through the hole. Many of the rotors available in the aftermarket are nothing more than inexpensive offshore manufactured stock replacement rotors, cross drilled to appeal to the performance market. They are not performance rotors and will have a corresponding high failure rate"

Grassroots Motorsports:
"Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the same gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)

Power Slot:
"At one time the conventional wisdom in racing circles was to cross-drill brake rotors to aid cooling and eliminate the gas emitted by brake pads. However, today's elite teams in open wheel, Indy and Trans Am racing are moving away from crack prone, cross-drilled brake rotors in favor of rotors modified with a fatigue resistant slotting process."

Stop Tech:
"StopTech provides rotors slotted, drilled or plain. For most performance applications slotted is the preferred choice. Slotting helps wipe away debris from between the pad and rotor as well as increasing the "bite" characteristics of the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage. Many customers prefer the look of a drilled rotor and for street and occasional light duty track use they will work fine. For more severe applications, we recommend slotted rotors." (Note that even though Stop Tech sells both drilled and slotted rotors they do not recommend drilled rotors for severe applications.)

Wilwood:
Q: Why are some rotors drilled or slotted?
A: Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity."
 

·
Banned
Joined
·
351 Posts
Discussion Starter #16
Wrong. Drilled rotors can actually create more heat as the braking surface where the pad contacts the rotor is decreased. The pad transfers heat into the rotor. A blank rotor has more surface area that can absorb and dissipate heat than a cross drilled rotor which has less surface area due to the holes. Larger contact surface = cooler. From Wilwood: Drilling diminishes a rotor's durability and cooling capacity.

Can you name one professional race series that currently uses drilled rotors? Formula 1, NASCAR, Indy Car, ALMS/Le Mans, Australian V8 Supercars, and WTCC cars do not use drilled rotors. If there was any benefit or improved performance, you would see them used in at least a few of these race series.
These ^^ are the two points of your I'd like to address.

1. More surface area can absorb more heat - alright. But with a better airflow over and through the heat sink, it can be made smaller yet dissipate more heat

2. Durability issue; other means can be used to achieve target rotor cooling with out sacrificing durability
 

·
Premium Member
Joined
·
1,605 Posts
I had D/S rotors on my Pontiac and wasn't a big fan of them at all. The car actually felt like it had more trouble braking than it did with the stock rotors. Personal opinion.
 

·
Banned
Joined
·
351 Posts
Discussion Starter #18
Wrong. Drilled rotors can actually create more heat as the braking surface where the pad contacts the rotor is decreased. The pad transfers heat into the rotor. A blank rotor has more surface area that can absorb and dissipate heat than a cross drilled rotor which has less surface area due to the holes. Larger contact surface = cooler. From Wilwood: Drilling diminishes a rotor's durability and cooling capacity.

Ok, so here a good example denting the reasoning above.

The following are the pictures of Asus' router RT N66. First picture is of a preproduction model, and it has a small heat sink with an active cooling. The second picture is the same router, but a production model, in which there is no more fan, but a very large heat sink in place.

Could it be that Asus' thinking is similar to racing companies not using cross-drilled brakes? (durability)

1.

2.
 

·
Banned
Joined
·
351 Posts
Discussion Starter #20
From brakes...to router. ;)

Great cooling analogy. :lol:
lol! principles of physics are universal. a heat sink is what heat sink does, right Forest?:lol:
 
1 - 20 of 25 Posts
Top