Are the benefits significant for front, 11", drilled and slotted rotors compared to smooth (64 malibu convert power brakes)? Looking at Summit's brand, conversion kit...gift certificate in hand. Merry Christmas! Thanks!

Actually, a plain rotor will perform better than a drilled rotor.

Drilled rotors are notorious for cracking because of the holes, and actually get hot faster because there is less material. They do look pretty though. :clonk:

Derek, thanks for all your time/advice over the past year!! Hope Santa brought you some cool stuff. I'll put the extra $ toward steering upgrades!! John

Actually, a plain rotor will perform better than a drilled rotor.

Drilled rotors are notorious for cracking because of the holes, and actually get hot faster because there is less material. They do look pretty though. :clonk:

So true, I bought a pair of X-drilled for my f-body and loved the looks but hated the performance of them. Another problem people have (me for example) is that most companies that dont charge 200+ a rotor use a stock or stock style rotor and put holes in them which take weight off the rotor and take alot more pedal to do alot less work.

Actually, a plain rotor will perform better than a drilled rotor.

Drilled rotors are notorious for cracking because of the holes, and actually get hot faster because there is less material. They do look pretty though. :clonk:

Derek,

While theoretically true, quantitatively, how much better will a plain rotor perform? Is there any published data?

Even more important, how will an 11" plain rotor perform for street driving versus a cross-drilled one? Will there be ANY noticible difference in braking?

I have heard about the "notorious for cracking" too, but I had heard that was only for "severe" duty (race cars with really high heat/glowing rotors) OR on cheapo cross-drilled rotors where the sharp drilled edges can cause stress risers and lead to cracking). Street (and infrequent track usage) with champhered holes, I have not seen cracking problems... I would venture a guess that companies like Raybestos would NOT risk the liability of selling cross-drilled rotors IF cracking was really an issue...


Drilled rotors... actually get hot faster because there is less material

Is there ANY data to support this? Theoretically, yes, there is less material, and therefore more heat would be generated for the same stopping pressure, but more of the material is exposed to cooling airflow which reduces the heat (especially in a vented rotor, even if just the crappy non-directional vanes)...

Don't "real" race cars (professional) still use cross-drilled rotors? Although these rotors are specifically engineered for racing applications, and not just a "stock" set that was drilled later...


Finally, just for those that will someday look at this thread; We do alot of things on our cars that don't offer the absolute best performance (such as wheel/tire combos, big stereos, etc.)... Unless you are a hardcore racer, asthetics do also usually come into play, and with that said, the cross-drilled rotors do look "impressive" to probably 99% of the people out there, with the reduction in performance being negligible in a street car...

What I've read about this issue is that the advantages of the cross drilled and slotted rotors only come into play under "race" conditions. Brakes work by converting rotating (or kinetic) energy into heat energy. The slotted rotors absorb the heat energy quicker, but also cool quicker due to better venting. This allows them to burn off the kinetic energy and quickly cool down for the next turn.
A "standard" rotor will take longer to heat up, but will also take longer to cool down. This will lead to brake fade under "race" conditions.
That being said, The above post's are correct for a street driver. On the street the con's out weigh the pro's for the slotted rotors.

For 100% street driving, I seriously doubt you'd ever notice a difference, or ever have a problem with plain, drilled, or slotted rotors... and I agree, they do look good, but the question was whether they provided a performance benefit, for which the answer is "no".

I strongly recommend this, of all links for anyone considering drilled rotors as an "upgrade" (Warning: some foul language and some very stupid people who argue with some very intelligent people :D ) In spite of all the BS, there is some excellent tech in there. :thumbsup:

http://corner-carvers.com/altimathread.php.html

Intended use is 99.9% street, .1% strip. Last pass was 17.6 sec, 88 mph with plenty of time to stop. I read the link Derek...thanks. Smooth 11" rotors sound to be the fit. Thanks!

Even more important, how will an 11" plain rotor perform for street driving versus a cross-drilled one? Will there be ANY noticible difference in braking?I really doubt you'll feel a difference, but from what I've read (no personal experience), pad wear is noticeably worse with a drilled rotor.

I have heard about the "notorious for cracking" too, but I had heard that was only for "severe" duty (race cars with really high heat/glowing rotors) OR on cheapo cross-drilled rotors where the sharp drilled edges can cause stress risers and lead to cracking). Street (and infrequent track usage) with champhered holes, I have not seen cracking problems... I would venture a guess that companies like Raybestos would NOT risk the liability of selling cross-drilled rotors IF cracking was really an issue...On the street, nobody seems to have problems with them (aside from the pad wear), but when taken to the track, and used hard, they can, and will crack. Removing material makes them weaker, and the holes themselves are a stress riser. Companies like Raybestos don't have much to worry about - problems on the street are highly unlikely, and anything that occurs on a race track they could just say it wasn't designed for that heavy of use, and get out of any lawsuit pretty easily I would assume.

Is there ANY data to support this? Theoretically, yes, there is less material, and therefore more heat would be generated for the same stopping pressure, but more of the material is exposed to cooling airflow which reduces the heat (especially in a vented rotor, even if just the crappy non-directional vanes)...The rotors ability to absorb the heat energy is more important than its ability to dissipate it. If you remove material, the temperatures will get hotter if heat energy is the same. This is a small ammount of material, so I don't think it's really as much of an issue as the strength concerns.


Don't "real" race cars (professional) still use cross-drilled rotors? Although these rotors are specifically engineered for racing applications, and not just a "stock" set that was drilled later...No professional teams use drilled rotors that I'm aware of. As stated in the link I posted, Rally cars use slotted to clean the pads, but most series use plain rotors.

Finally, just for those that will someday look at this thread; We do alot of things on our cars that don't offer the absolute best performance (such as wheel/tire combos, big stereos, etc.)... Unless you are a hardcore racer, asthetics do also usually come into play, and with that said, the cross-drilled rotors do look "impressive" to probably 99% of the people out there, with the reduction in performance being negligible in a street car...I agree. :) They look cool, and impressive to most people. There are even a few things I plan to do to my car yet that will cost extra money just for looks, some might even hurt the performance. (shhhh... don't tell anyone :D )

As has been said, slotted is OK but not really necessary given modern pad compounds and X-drilled isn't worth paying extra for. You are paying extra to lose additional rotor surface area for the pad to clamp against and also paying extra for more places where a crack can start.

Crossdrilling does almost nothing for cooling (the airpath on a directionally vented rotor is from the hub out through the vanes around the circumference, not through the holes) and the holes only serve as crack propagation points. They do look neat though.

I've seen more cracked crossdrilled rotors than I care to count, some to the point I'm amazed the car made it off the track safely. Granted all the cracked crossdrilled rotors I have picked up were off track cars but even casual weekend track cars suffer from it eventually. Solid rotors can heat check & crack too, but it takes longer for them to do so than crossdrilled.

All that being said, I have yet to see a crossdrilled rotor on a STREET car that sees "sane" usage develop cracks. If the car sees severe/hard street duty or especially improper hard use (i.e. beating on the brakes prior to getting a little heat in them, or abusing them and then immediatly parking the car which causes uneven cooling as one part of the rotor sits in the pads/caliper) then you can crack a rotor from street use.

I have 1 small crack on the inside of one my front Baer rotors (they're slotted & crossdrilled); my car is street only (so far) but my brake usage is definitely not covered under most people's definition of "normal wear and tear" (i.e. I'm doing max effort stops from the 150-160mph range back down to 60mph or less 8 out of 10 times I drive the thing.) I'm very hard on brakes, but I warm them up before abusing them and then give them some cool down time but in the end the elevated temperatures of heavy use and the heat cycles take their toll... and they take their toll faster on a crossdrilled rotor because of all the holes that serve as good places for a crack to start. I will be replacing them with solid rotors. The solid rotors might not get as many "oohs and aahs" at carshows but I really don't care about that. If I did I would have fixed the rust holes in my fenders 10 years ago. :p

I installed a set of drilled and slotted rotors that I got from OPGI. They are very heavy duty. The only reason I bought them was for the look. The biggest problem I know of associated with slotted rotors is that they can't be turned (according to a CarQuest guy I spoke with).

Smooth is the way to go for the street, as you'll find you cannot machine cross drilled discs. Once it's time to change the pads, its time to change the discs. Just go with smooth discs, really good pads, and quality fluid, and you'll be laughing. Leave the crossdrilled/ slotted to the show cars.

Smooth is the way to go for the street, as you'll find you cannot machine cross drilled discs. Once it's time to change the pads, its time to change the discs. Just go with smooth discs, really good pads, and quality fluid, and you'll be laughing. Leave the crossdrilled/ slotted to the show cars.
Agreed, use a quality american made rotor and good pads and fluid and be satisfied. Also many of you guys were stating that you would have no noticable difference from X-drilled and sloted rotors, I in fact did. I noticed a decrease in breaking ability. I will admit I used a less popular brand rotor and not the high end. My combo was X-drilled and slotted rotors with hawk pads nad fresh fluid. Hated the performance. Although I did put 8k on them and never cracked them, did several 100+mph stops.

Gokou,check with Baer on that rotor it should be under warranty.
At least Baer drills their rotors in a counter rotational direction so the lines of holes run counter to the cooling vanes which makes it really hard for a crack to "connect the dots". Their brakes are available with smooth rotors too for about $60 less.
I have cross drilled and slotted rotors on one of my cars. I got them for basically nothing,brand new. I don`t know what brand they are. I replaced the worn Perf.Friction pads and old rotors with fresh PF pads and the new drilled/slotted rotors and noticed....nothing. Well except that the brakes didn`t pulse,which is why I was replacing the old rotors. They don`t work any better or worse in this case. No cracking so far and pad wear seems normal too. I guess they look cooler... Mark SC&C

Smooth is the way to go for the street, as you'll find you cannot machine cross drilled discs. Once it's time to change the pads, its time to change the discs. Just go with smooth discs, really good pads, and quality fluid, and you'll be laughing. Leave the crossdrilled/ slotted to the show cars.

You can most definitely resurface crossdrilled and slotted rotors. You have to take very light passes with the brake lathe however as if you take too heavy of a pass you risk chipping the cutting inserts on the brake lathe over the slots/holes.

Just to clarify re: the REASON for the drills/slots. It's to remove the gasses that develop under severe braking, which leads to brake fade. The gasses act as a barrier between the pad and rotor - the slots and holes allow the gasses to escape, and reduce or eliminate fade.

They are not there to clean the pad, or alter the amount of heat the rotor can absorb/dissipate.

I have slots on my chevelle and my daily driver (Bravada). I got them on the Bravada because I had brake fade with all my highway driving and an occassional heavy stop - after putting the slots on, I've never had fade again.

Just to clarify re: the REASON for the drills/slots. It's to remove the gasses that develop under severe braking, which leads to brake fade. The gasses act as a barrier between the pad and rotor - the slots and holes allow the gasses to escape, and reduce or eliminate fade.With modern pads, outgassing is pretty much non-existant.

Just to clarify re: the REASON for the drills/slots. It's to remove the gasses that develop under severe braking, which leads to brake fade. The gasses act as a barrier between the pad and rotor - the slots and holes allow the gasses to escape, and reduce or eliminate fade.

They are not there to clean the pad, or alter the amount of heat the rotor can absorb/dissipate.

I have slots on my chevelle and my daily driver (Bravada). I got them on the Bravada because I had brake fade with all my highway driving and an occassional heavy stop - after putting the slots on, I've never had fade again.

With mediocre or older forumulation pads this is true. Most run of the mill parts store pads do outgas like crazy when hot especially organics and semi-metallics... in this case slots would be a benefit. But running better pads is a better solution. Track cars (even the fast ones) running solid rotors and good pads don't have a problem with brake ineffectiveness due to outgassing even at sustained temperatures far exceeding what you would see on a street car even after a couple freeway panic stops.

I hear you on S-10 Blazer platform poor braking... my Mom's Bravada is the same way. TERRIBLE if you have to make a hard stop, not to mention half the time that crappy Kelsey-Hayes ABS unit wants to "let go of the brakes" for about 1/2 a second at the first activation. Good pads (Hawk) cured the poor stopping on her Bravada... at least for the first couple hard stops then they overheat. They are a street-friendly compound after all. I could make that thing stop like crazy over and over with some nasty race pads but I bet the rotors would only last a month. The real problem with the S-10 blazer platform is that the brakes are just way too small to cope with a 4400lb curb weight and heatsoak very quickly.