Can someone tell me the relative benefits of slotted vs. drilled rotors? Any negatives compared to solid ones?
This is what I remember, someone can correct me if I'm wrong.
Drilled rotors tend to be weaker than slotted, weaker meaning that they crack easier.
Porsche I believe are cast with the holes in them so they retain their strength.
Compared to solid ones, I do believe there is more wear on the brake pads.
Benefits on drilled/slotted rotors are lighter weight and more importantly, less brake fade because they dissipate heat faster.
Anyone have slotted on their cayman? How do they compare?
aaron is correct.
i am not aware of slotted rotors for our cars. if anyone finds them, pls post.
This question hits all the forums on a regular basis. The rotor manufacturers have interesting statements on the issue.
http://www.wilwood.com/Centers/Information/Pages/faqs.asp#question7
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.
Slots or grooves in rotor faces are partly a carryover from the days of asbestos pads. Asbestos and other organic pads were prone to "glazing" and the slots tended to help "scrape or de-glaze" them. Drilling and slotting rotors has become popular in street applications for their pure aesthetic value. Wilwood has a large selection of drilled and slotted rotors for a wide range of applications.
http://www.stoptech.com/tech_info/faqs.shtml
Which is better, slotted or drilled rotors?
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.
http://www.baer.com/
Tab "Baer Tech", tab "Frequency Asked Questions"
What are the benefits to cross-drilling, slotting, and zinc-washing my rotors?
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.
Brembo is the odd man out.
http://www.brembo.com/Brembo/Templa...Qs/&NRNODEGUID={3FE5A10D-634E-4B3E-9C89-C60174F98D3D}&NRCACHEHINT=NoModifyGuest
Why use drilled or slotted discs?
Drilling or slotting discs aids the disc in several ways:
The edges of the slots or holes continuously clean and refresh the pad surface as well as providing increased brake "bite". Additionally, they prevent gasses from collecting between the pad and disc interface.
The disc is lightened, thereby decreasing its rotational inertia.
Improved ventilation increases the disc's ability to shed heat, resulting in cooler operating temperatures
Very interesting and much thanks.
Not a word about water...... One of the best benefits of a drilled or slotted rotor is it's ability to shed water from between the pad and the rotor much faster than a conventional rotor.
Has anyone ever looked at a vented rotor? It's got these nice air passages between the front and back surface to let air cool it. When the rotor is spinning, centrifugal force will cause the air inside these passages to be thrown out, right? Well yeah, but there is no where for new air to enter those passages, unless of course they are drilled rotors. If they are, the rotor becomes a fan with a constant stream of air passing through it while spinning. This has to cool the rotor more quickly.
Reduced weight, water displacement, cool looks are all secondary benefits.
As far as cracking, has anyone here ever replaced a rotor because of cracks? Raise your hand..... With today's rotors, that really are not drilled but cast with the holes, the rotor surface will be worn beyond it's usable limits long before it ever thinks about developing a crack.
Check out the pictures at
http://forums.corvetteforum.com/showthread.php?t=1024509&page=3
Interesting read. But let me guess..... Do Corvettes have slotted or drilled rotors?
I do believe that a properly designed conventionally vented rotor can dissipate heat just as quickly without holes. It will be interesting to see if anyone switches to non drilled rotors for track.
I have a 2000 Passat. From day 1 the car would scare the **** out of me in the rain. If I drove for 3 minutes or more without braking, even on a slightly wet day, when I would need to brake the pedal would be rock hard but there would be no brakes at all for 1-2 seconds, which seems like an eternity when you want to brake. I complained to VW, but they told me there was no found problem. After a few near collisions, I bought drilled rotors. The drilled rotors exhibit the same problem, but only for fractions of a second. Huge improvement in wet weather braking.
I think some of the higher end models of cars have some technology that 'wipes' the rotors when it detects water on them to prevent the water buildup.
I seem to remember BMW or Mercedes having this feature.
I'm sure it'll eventually trickle down to lower end cars eventually.
Until the C6, all Corvettes came with plain, flat rotors. Even the C5 Z06, which has incredible braking. For the C6, you can get drilled rotors with the Z51 performance package. My belief is that these were added for the cosmetic appeal.
The whole slotted vs. drilled debate is a messy rat hole.
Basically, any rotor can crack (solid, slotted, drilled).
Buy good quality and pick the one that you like based on whatever rotor religion you have affinity to.
Remember, Porsche uses drilled rotors on the GT3 race cars. Maybe they know something about brakes... just maybe
I've tracked quite a few Porsches, all on OEM drilled rotors, and not one has cracked beyond the normal small cracks that develop around the holes.
As others have pointed out, the C5 Z06s cracked their rotors after 4 track days ('course, they cost only $22 each, so you just have to get used to changing them often).
