jon0886

iTrader: (1)

FINALLY!! THE MYTH JUST NEEDS TO DIE!

So guys... what do you think about those powerstop rotors? I've been thinking about getting them for my car.

=P

So slotted rotors are ok, although not really too functional - just a bit?

Carl Byck

Damon, I use power slot fronts on my FC, they definitely "flutter", both audibly, and as feedback through the pedal. That said, you actually get used to it, and it gives you an audible/tactile cue as to how the brakes are working. They do wear pads a little faster as well. I like them in addition due to the "theory"
that if you glaze your pads it will clean them up quickly (read, wear) As for brakes with cast holes, there are several, in fact SCC magazine used them in their project FD, until they failed on the street LOL. So, my vote is for slotted(pad wear aside) followed by solid. Carl

DamonB

I've never been on the power slots but I have been on other slotted rotors. At very slow speeds I could feel a very slight vibration in the pedal but I heard no new noises from them. Maybe the pad squeal drowned it out

spoolin93r1

so basically everyone is sticking to their guns about the cross drilled being junk without providing proof? seems to be the way it works around here. and sorry, but brembo does do their own drilling in house with their brake kits. if they were so called "junk", then i doubt ferarri would consider them. some people just need to get off their high horses

Sonja

I have been running Stillen Cross-Drilled Rotors for about a year now. No cracks, no fading, no problem. I like the way they look. You can call me a ricer all you want, But all of you have at least one thing on your car because you like the way it looks. Later.

jimlab

What would you consider proof?

Fact: Experience has proven that crossdrilled rotors can develop cracks under hard track use.

Fact: Modern brake pads no longer out-gas as badly as they did decades ago, so the argument that crossdrilling to vent gasses is required is no longer valid.

Fact: Larger rotors (diameter, thickness) dissipate heat more quickly than smaller rotors. Crossdrilling reduces surface area and mass, so the argument that it improves cooling or braking performance is not valid either.

Crossdrilling and even slotting are appearance modifications only these days. People justify them by using arguments like the ones above because it makes them feel like they got more for their money, but the facts are that a solid rotor will perform just as well as a drilled or slotted rotor of the same size. However, people want the performance look, so they buy drilled/slotted rotors, even if they provide no increase in performance. Does painting a brake caliper red improve its clamping force?

Brembo does not make stock replacement crossdrilled rotors for the FD. The ones you see for sale on Ebay and elsewhere are drilled by a third party prior to sale. I believe that is what people were trying to say. Brembo obviously does produce crossdrilled rotors for other applications.

That's the best you can do? You accuse people of calling crossdrilled rotors "junk" even after they provide evidence to support their opinions, and your only counter-argument is that Ferrari uses them, therefore they must be good?!?

Some people apparently need more intelligence to understand what's being said in this thread...

DamonB

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

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."

From 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"

From 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."

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 some 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?)

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."

also from AP: "Cross drilled...can compromise disc life. Radiused drilled...mainly used for aesthetic reasons on road applications."

...I'll keep looking for more. Note that these quotes are from people who are in the racing business, not the poser business.

VividRacing.com

I completely aggree with the origional post. Slots are better for daily driving, racing, and removing the dust and gasses. In my experience the drilled rotors usually end up cracking under hard use, especially when paired with super agressive, abrasive pads. I'm currently running the StopTech big brake kit on my RX8 and I'm using the slotted rotors. They have proved them selves over and over again on and off the track. The drilled are great looking for show cars or a daily driver that will never see the track but for full functionality the slots are the way to go.

Net Seven

iTrader: (5)

Can you still have slotted rotors turned if they get warped?

DamonB

Yes.

shawnk

Guess I am going to go pull my wilwoods and throw them in the trash...

Nah I guess I will just wait til they crack and then do it...

Shawn

CokeRx7

then what about the brake rotors with the slated wholes.... like the slit pattern wholes... which would be better.. the slit ones or the wholes in the slit pattern...
cuz im lookin to buy some brake rotors soon and new calipers...

Radical Rotary Avantgard

spoolin93r1, where is your Ferrari fact about their rotors, that you didn't even know they were ceramic?????

spoolin93r1

might wanna check into that. not all of them are like that. same with porsche. sorry, but i'm going with what's been out there and what has worked. not with people's ideas. i'll stick to hard evidence. until someone provides me any solid evidence that quality drilled rotors are really that bad, i'm stuck in my way

jimlab

Well then here's to your first set of cracked rotors, and that hard head of yours.

In case you hadn't noticed, you're not driving a Ferrari or a Porsche. You'd be better off listening to other people who track RX-7s regularly...

Fatman0203

Was this mentioned that ferrari and porche i beleive FORGE or cast (w/e is better) their rotors with the drills already in them? And not have them drilled aftermarket? Just wondering?

spoolin93r1

brembo does not cast anything into their rotors. they are drilled afterwards, hence the name. feel free to call them up and talk to them. and if i were into tracking my car heavily, i might be willing to research more, but 95% or more of the cars on this forum or used for street duty. i have yet to see and/or hear of a set of quality rotors cracking due to the drilling, on the street. like i stated before, i've seen regular, non-drilled rotors crack and fall apart. no rotor is perfect and there will be flaws. and also, noone is willing to provide any proof, as i've asked for many times

spoolin93r1

how many have you personally cracked and/or seen cracked?

jimlab

You haven't read a single word anyone has posted, have you.

What does that have to do with your ignorance?

spoolin93r1

exactly my point. no solid proof. just because it's happened before doesn't mean it's going to happen to them all. you can keep talking down to ppl to make yourself look better if ya want, but it still doesn't solve anything

DamonB

Forging and casting are two completely different processes. Forging is not used to make brake rotors by anybody.

Forging is essentially smashing a chunk of metal between a tool and die so damned hard that the metal forms to the shape of the tools. This is done with thousands and thousands of pounds of pressure. The metal is formed while in its solid state.

Casting involves melting the metal and then pouring the liquid metal into a mold. Once the metal cools it hardens into the shape of the mold. The mold is then removed.

There are pros and cons to both but nobody forges brake rotors. The shape of the part does not lend itself to forging.

Your whole idea of "whichever is better" doesn't apply. It's "whichever is possible".

Fatman0203

Alright then casting it is. Then from my understanding those big name companies "cast" their brakes with those hole's in them already.

DamonB

The only people who cast their holes in are Porsche (I'm working on verifying this). Anyone else who holes their rotors drills holes in them with a drill, hence the term "crossdrilled".

Fatman0203

Thanks, well isnt that supposed to be alot better than actually drilling them?

jimlab

If you don't want to be talked down to, perhaps you should make an effort to make statements that indicate that you've read, considered, and understood what others have said. I'm talking down to you because the best argument you've been able to provide so far is that "Ferrari does it so it must be good". Do you have any idea how ignorant that sounds? Probably not, or you wouldn't have posted it in the first place.

I believe it's been said before in this thread (but evidently you didn't read it, or didn't understand it if you did) that drilled rotors are fine on the street. They have a tendency to crack if they're undersized for the application when used on the track. This is not opinion, this is statement of fact. Drilling creates sharp edges along which stress risers can form. When overheated and cooled rapidly, the metal can crack along the points of stress. Rounding or chamfering the outside edges of the hole makes no real difference, because there are still sharp edges created inside the rotor which can't be cleaned up to relieve them. Find a book on machining metal and read up on the subject if you don't believe me.

Bottom line, buy what you want. If you want to buy drilled rotors, buy drilled rotors. Just quit asking for other people's opinions and advice if all you're going to do is whine and argue about it because you don't like what you're hearing.