timothyrw

double post

ZZmustang

Crazy Al
I think your posts are " sone of the biggest piles of BS that I have ever seen! "

But thanks for your opinion on my post.

timothyrw

Here is some ACTUAL evidence everyone can consider.

Brembo designed thecomposite carbon/ceramicbrake system for the Ferrari F2002 used in Formula 1 races. Those brakes were then put on the Ferrari Enzo.

They were cross drilled...

http://www.supercars.net/Pics?v=y&id...ari_Enzo43.jpg

CrazyAl

No, they're not giving brakes away. However, Wilwood's main market is actual (non street legal) race cars--Nascar, Can Am, Outlaw, and so forth. "Street" use is a small portion of their business. They don't need tohawk their products as their market is already well established. Professional race teams use highly drilled rotors on their cars for weight savings purposes, and consequently they get people who want to use their racing rotors on street cars. This has lead to problems in which a customer uses racing brakes (which are intended for a lightweight stripped-down car, and frequent replacement) on a street car which is much heavier.

Advertising is not exactly gospel. I see ads every day for stocks that are guaranteed to make me a millionaire overnight, and pills that will add inches to my johnson, but that doesn't mean that these things are true. Think about it. If cross-drilled rotors really were better than solid rotors, you would see much more of them on vehicles from the factory. 95% of this "cross drilling helps heat dissipation" BS comes from overseas vendors trying to sell people their snake-oil brake products. Auto makers such as Fordspend a lot of money enigneering their brake systems. They know what works and what doesn't.

As for the "logic" of the situation, that is what the marketing people are counting on to sell brakes. First off, look at one of these street-style drilled rotors like a Powerstop. Those holes are not even 1/4" in diameter and there aren't very many of them. Do you really think that an appreciable amount of air is going to move through those holes?

Let me explain in detail why the holes do not cool appreciably. When a brake disc is spinning, the hollow passages inside the rotor (the vanes and channels) act like a centrifugal pump. Air from the center of the disc (the hub area) is pulled through those channels and is blown out the "rim" of the rotor. This is how rotors cool themselves down. The interior surface area of these channels is very large, and the vanes themselves act like heat sink fins to carry heat into the air. When the disk is spinning, it literally PUMPS air through itself to cool itself down. Cheaper rotors have straight vanes in them becasue this design is easier to manufacture. Premium brake rotors have directional or curved rotors. Why? becasue just like the rotor in a proper pump, curved vanes are more efficient at moving the air through the rotor. When the rotor is spinning, air is moving in a radial direction (like spokes on a bicycle wheel). The drilled holes in a rotor are perpendicular to this direction--they are oriented axially, not radially. Consequently they are pointed the wrong direction for air to be flowing through them. If that doesn't make sense, think of it this way: Pretend you are trying to drive out of a small driveway that has a T-intersection with a very busy street. You cannot move very quickly becasue you have to wait for an opening in traffic before you can get out. Furthermore, the holes have very low surface area compared with the rest of the rotor. Think about the total effective area of a brake rotor: both sides (braking surface) plus the area of all those channels inside the rotor. Now think about the surface area of the inside of a hole. The additional surface area gain by drilling holes is a tiny fraction compared to the rest of the rotor.

That is not entirely true. I have suggested three books, all of which are well regarded in the professional community and have withstood the scrutiny of countless engineers and scientists.

Of course, Brembo et al have done their research. But their goals may be a lot different than yours or mine. Let's look at the claims made here. The OP post claims the reason for drilling rotors is to dissipate heat. Brembo says nothing about dissipating heat and instead says that the holes refresh the pad surface.

The OP post is simply wrong, and I have explained why and provided documentation to back it up.
Brembo has a bit of point. Holes do cause some degree of scraping of the pad surface, and that can (slightly) improvefriction if used with the right kind of pads. Now then, this also happens to shorten pad life becasue the pads are being constantly scraped. That is a tradeoff, just like the highly drilled race rotors.

If you get the highly drilled rotors, you do get some benefits: decreased weight and perhaps a small increase in pad friction. But you also have to replace your parts more frequently. That may or may not be OK with you.

You are confusing what is needed to stop for general use with what is nice to have for performance situations. Your 1300C has one rotor becasue that is all that is needed for safe use of the motorcycle. The 1800C is an upgraded model which simply has better brakes than the 1300C. The 1800 doesn't NEED the better brakes. It just has them for better performance. This is very common in motorcycles. For example, with Ducatis there are various "grades" of each bike. The cheapest model variant is called the "Dark". Dark models typically have less expensive suspension components and they ususally only have one front brake disc. The standard models--which have exactly the same engine--have two brake discs. It's just a higher performing model. The same is true with the Mustangs. The GTs have larger brakes than the V6 models, despite being essentially the same weight.

The CBR1000RR doesn't need two brake discs at all. It simply has them as a performance upgrade. In fact, on some racetracks when hard braking is not needed, some riders remove the second brake disc for more weight savings.

And yes, for a Z06 to have the same braking as a CBR1000RR (assuming the tires hold, of course), it would need much more rotor area.

[quote]
What I would like to

CrazyAl

Perhaps my first post wasn't particularly clear. I am not saying that cross-drilled rotors don't have some advantages.They do.Drilled rotors can reduce rotating weight. I am saying that the original post by ZZ mustang isfactually incorrect. The reason for cross-drilling is NOT for heat dissipation and it does NOT improve stopping power.

Cars like Ferraris have cross-drilled rotors for weight reduction purposes, and becasue of this they also have a muchmore frequent maintenance schedule.

CrazyAl

The Roush kit is made by Stoptech.

RodeoFlyer

Al knows his brake stuff - listen to him!

just upgrading my lines/fluid, adding Hawk pads , and ducting made a WORLD of difference. Start there

CrazyAl

ZZ, if I offended you, I apologize. I did not intend to call you names--in fact, I didn't even think that you wrote that post at all.

I thought your post was simply cut-and-pasted from somewhere else. The poor English of the post and the choice of wording makes it sound like it was written by a cheap foreign shop trying to hawk their products. And you know what? Google for the first sentance of your post and what do you find? That text is advertising garbage from an Ebay vendor selling cheap Chinese "performance rotors".

fairlane292

CrazyAl: Next to all the incredible info you continue to provide on this MF which helps us all so much... you know what I really admire about you? When people challenge you, particularly in a very unprofessional or immature way you simply ignore that behavior and stick with the subject matter. Don't ever change this way about youor leave this forum, becausea few people don't appreciate you. I'm sure you already learned a long time ago that you will find that anywhere you go. You are extremely knowledgeable and inspiring and apprecaited by so many.
Thanks again!

timothyrw

Ok, I went to Baer.com and found the following...

In years past, cross-drilling 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 began to break down at extreme temperatures. This condition is often referred to as "green pad fade" or "outgassing". When it does occur, the driver still has a good firm brake pedal, but simply little or no friction. Since this normally happens only at temperatures witnessed in racing, this can be very exciting! However, with today´s race pad technology, ´outgassing´ is no longer much of a concern. When shopping for races pads, or even ultra-high performance road pads, look for the phrases, "dynamic surface treatment", "race ready", and/or, "pre-burnished". When these or similar statements are made by the pad manufacturer, the pad in question will likely have little or no problem with ´outgassing´. Ironically more pedestrian pads used on most streetcars will still exhibit ´outgassing´, but only when used at temperatures normally only encountered on the racetrack. Although crossdrilling and/or slotting will provide a welcome path to expend any gasses when and if they develop, it is primarily a visual enhancement behind today’s often wide-open wheel designs. Crossdrilling offers the greatest gas relief pathway, but creates potential "stress risers" from which cracks can occur. Baer´s rotors are cast with crossdrilling in mind, from the material specified, to curved vanes, behind which the holes are placed to minimize potential crack migration. Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer’s offerings.

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Slotting increases the bite of the pads and helps the car to decelerate more rapidly. The process doesn´t involve removing as much metal as cross drilling, so it doesn´t result in as great a weight saving. Slotting, however, is even more effective than cross drilling in combating the problem known as "out gassing". This occurs when, at very high braking temperatures, the bonding agents used in some brake pads produce a gas. Under extreme conditions, this gas can create a pneumatic cushion between pad and rotor, giving a driver a normal pedal feel but reducing the amount of friction being generated. The slots pump away this gas and restore full contact. The "micro-shaving" effect of the slots also serves to de-glaze the pads (this is why the edges of the slots on EradiSpeed rotors are not chamfered or "radiused"). It also tends to even out the wear across the brake pad faces, increasing the effective contact area. This can extend rotor life.