More on drilled vs. slotted rotors
#1
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More on drilled vs. slotted rotors
More facts about rotors. May the great myth of drilling rotors for improved cooling finally die...
Darrick Dong; Director of Motorsports at Performance Friction.
"In the days of asbestos pads there was a gas boundary layer that appeared at the interface area of the pad and rotor. Although that gas boundary layer still occurs it is much less of a problem with modern friction materials. Slots are more than adequate to carry that gas away. Years ago that gas boundary, along with reducing weight, led to the popularity of drilled rotors. However, in the intervening period, the myth has persisted that cooling is the main reason for drilled rotors. Anyone that tells you that drilling makes the disc run cooler is smoking crack."
Why is Dong so adamant? Because he works with racing brake systems for a living and it isn't too hard to take two identical rotors, drill one of them and slot the other, put them on a brake dyno and measure temps and life.
Darrick Dong; Director of Motorsports at Performance Friction.
"In the days of asbestos pads there was a gas boundary layer that appeared at the interface area of the pad and rotor. Although that gas boundary layer still occurs it is much less of a problem with modern friction materials. Slots are more than adequate to carry that gas away. Years ago that gas boundary, along with reducing weight, led to the popularity of drilled rotors. However, in the intervening period, the myth has persisted that cooling is the main reason for drilled rotors. Anyone that tells you that drilling makes the disc run cooler is smoking crack."
Why is Dong so adamant? Because he works with racing brake systems for a living and it isn't too hard to take two identical rotors, drill one of them and slot the other, put them on a brake dyno and measure temps and life.
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#9
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Doesn't help keep them cool...but the holes do help them look cool. They will never go away because of that. Show and street cars will still have them. Can't call them stupid, just fashionable. Have you seen those starflake shaped rotors with most of the non-swept area removed to look pretty?
#10
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just wondering since he has access to do so, how come noone has ever posted results of the brake dyno? it seems everyone wants to downgrade drilled rotors, yet they never provide factual proof. i can understand the theories behind it, but i'd like to see evidence. if it wasn't worth doing, brembo and many other companies wouldn't still be doing it
#11
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Originally posted by roadsterdoc
Have you seen those starflake shaped rotors with most of the non-swept area removed to look pretty?
Have you seen those starflake shaped rotors with most of the non-swept area removed to look pretty?
Those are called scalloped rotors. The only reason why they are like that is for weight reduction. what do u mean by 'non-swept' area?
#12
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Originally posted by spoolin93r1
if it wasn't worth doing, brembo and many other companies wouldn't still be doing it
if it wasn't worth doing, brembo and many other companies wouldn't still be doing it
#13
Super Snuggles
Originally posted by spoolin93r1
it seems everyone wants to downgrade drilled rotors, yet they never provide factual proof.
it seems everyone wants to downgrade drilled rotors, yet they never provide factual proof.
Crossdrilling is fine for the street, especially if the edges of the holes are rounded to prevent stress risers (and eventually cracks) from forming, but anyone who thinks that it's anything more than an appearance mod needs to do some research.
if it wasn't worth doing, brembo and many other companies wouldn't still be doing it
Damon, I didn't see anything about "bling" mentioned in your post.
#16
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i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion. like i said, brembo has been doing it for years and is ovbiously going to continue doing so. a company with race heritage isn't going to care about looks versus performance. granted, i've seen cheap *** ebay rotors crack, but nothing of quality. hell, i've seen solid rotors crack before, does that mean they're junk?
#17
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Originally posted by spoolin93r1
i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion. like i said, brembo has been doing it for years and is ovbiously going to continue doing so.
i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion. like i said, brembo has been doing it for years and is ovbiously going to continue doing so.
#18
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Originally posted by spoolin93r1
i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion.
i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion.
#19
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Originally posted by spoolin93r1
i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion.
i'm sorry, but without any hardcore proof, it's hard to just believe someone's opinion.
If you don't believe the guy who works for one of the most preiminent brake companys in the world maybe you'll believe the real racers who race all over the world. Nobody in the modern world who uses iron brake rotors (F1 before carbon, CART, IRL, NASCAR, ALMS, WRC, TransAm, Formula Atlantic, F3000 etc) uses drilled rotors. Why? Because in racing it's performance that counts, not looks.
You guys keep your drilled rotors and the rest of us will just keep outbraking you late in the race
Originally posted by spoolin93r1
i've seen solid rotors crack before, does that mean they're junk?
i've seen solid rotors crack before, does that mean they're junk?
Here's some more rotor info here
#22
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That looks like a carbon rotor to me, which is a different ball game. Also some companies like Porsche that have rotors with holes in them are not drilled but are cast with the holes already in them. (Or so I have heard) This means the integrity of the metal isn't weakened as much.
I'm no expert on the subject but I know what I have seen over the years and that is cracked rotors that were drilled. Hell, I saw another set two days ago.
I'm no expert on the subject but I know what I have seen over the years and that is cracked rotors that were drilled. Hell, I saw another set two days ago.
#23
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Originally posted by SiKoPaThX
I'm struggling to beleive this....Sorry for the gigantic picture but BEHOLD! The Ferrari Enzo....
If they don't know about brakes...who does?
I'm struggling to beleive this....Sorry for the gigantic picture but BEHOLD! The Ferrari Enzo....
If they don't know about brakes...who does?
Porsche does it for looks. Anyone who believes different is giving Porsche too much credit.
#24
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The Enzo has carbon brakes, not iron brakes. Different set of rules apply.
As for Porsche casting the holes into the rotor: Casting the hole is a slight improvement over drilling the hole but still forms a concentrated area of stress. At the same time holes mean having less mass in the rotor and therefore less thermal ability while offering no increase in rotor cooling performance. Since the cast in holes still concentrate stress around the edges of the holes the rotor will at the very least have a shorter lifespan than a non-drilled rotor; most likely the holed rotor will have less performance too. This is true whether the holes are machined or cast.
I have not been able to verify that Porsche in fact casts the rotors with holes in them; I find that hard to believe. It's very easy to prove though: Examine the inside edges of the holes closely. If they have a shiny and smooth surface they were machined. If you can make out surface porosity from the casting they were in fact cast in place. I haven't wanted to appear rude and peer closely at anyone's Porsche brakes in the parking lot From now on whenever I come across a Porsche in the paddock with the wheels off I am going to stick my head in there. I'll let you know what I find...
As for Porsche casting the holes into the rotor: Casting the hole is a slight improvement over drilling the hole but still forms a concentrated area of stress. At the same time holes mean having less mass in the rotor and therefore less thermal ability while offering no increase in rotor cooling performance. Since the cast in holes still concentrate stress around the edges of the holes the rotor will at the very least have a shorter lifespan than a non-drilled rotor; most likely the holed rotor will have less performance too. This is true whether the holes are machined or cast.
I have not been able to verify that Porsche in fact casts the rotors with holes in them; I find that hard to believe. It's very easy to prove though: Examine the inside edges of the holes closely. If they have a shiny and smooth surface they were machined. If you can make out surface porosity from the casting they were in fact cast in place. I haven't wanted to appear rude and peer closely at anyone's Porsche brakes in the parking lot From now on whenever I come across a Porsche in the paddock with the wheels off I am going to stick my head in there. I'll let you know what I find...