There are so many opinions on this subject that I really don't know whom or what to believe. My understanding is that slots and drilled holes both help to remove water & gasses and keep the pads cleaner at the expense of reduced friction surface area. Cross drilling weakens the rotors making them more prone to cracking but also promotes better heat disipation which helps prevent cracking. Slots cause faster pad wear. Some say that blind holes (dimples) are preferable to cross-drilled holes because they don't weaken the rotor as much. Others say that pad gassing is a thing of the past and that blank rotors are best...

EBC has this to say:

"the biggest advantage of slotted rotors is the fact that they promote flat and parallel pad wear rather than allowing ridges to develop on pads and rotors which is typical of “drilled only” sport rotors. By preventing these ridges brakes stay more consistent throughout pad and rotor wear life"

According to Stoptech, drilled rotors are okay for normal street use but not for any heavy use such as racing or towing. Personally I think cross-drilled rotors look the best, offer some of the advantages of slots without the extra pad wear but worry about them cracking. I'm still undecided.

 

Apparently, blanks are used a lot for racing, Brembo blanks with Hawk HPS pads get strongly recommended. Drilled rotors only break if excessively heat stressed and anything vaguely similar to normal driving doesn't include the repeated hard braking necessary to generate such temperatures (not even stop and go traffic )! From reading, the drilled rotors used for professional racing are carbon, not iron, so that's a different ball game. Regarding pads, ceramic is great for reducing brake dust (non-sticky light gray instead of sticky dark gray) and providing long life. Downside is they brake less well than semi-metallic and rotors wear much faster.

PS. One should only consider installing either slotted or drilled if one is in fact changing to larger rotors and pads. That way pad contact area (for friction) and rotor mass (for heat absorption) are better preserved. Factory sized rotors should not be directly replaced with either slotted or drilled, stick with blanks.

 

You're into show and those new rotors definitely look cool, has to help ! I strongly suspect any braking improvement you notice is thanks to the semi-metallic pads, not the rotors. FWIW -- I've never managed to warp a rear rotor (have done some fronts, but took many years), my suspicion is you either had lug nut torque issues or it was just pad deposits causing varying friction.

 

I just spoke with StopTech and they pretty much confirmed that drilled rotors will hold up fine during years of normal street use. However, they do not recommend drilled rotors for anything beyond normal daily driving. So if you plan to tow, auto-x, track day or even just use your brakes hard, they recommend slotted rotors. They said that drilled rotors are primarily for show and provide little to no useful benefits. Slots OTOH, provide better initial bite, improved braking performance, some cooling improvement and more uniform pad and rotor wear.

If you really like the look of drilled rotors but use your brakes too hard for normal cross-drilled rotors, there are some options. Brake Performance and EBC offer "dimpled" rotors with blind drilled holes that don't weaken the rotors as much and StopTech offers cryo-treated rotors which are claimed to be 3x stronger and last 3x longer than conventional cast iron rotors. It's also worth noting that there are dozens of variables which determine the quality and performance of a brake rotor. The specific alloy formula, carbon content, casting and machining processes all factor in. So while a cheap cross-drilled rotor made in China will almost certainly crack with any hard use, a cross-drilled high-carbon rotor from Brembo or other reputable manufacturers most likely will not.

So if you have a show car and drive like Trevor, drilled or drilled & slotted. If you race, tow or drive aggressively, slotted or blank.

BTW, StopTech is the performance division of Centric, a CA based company making quality oem brake parts. StopTech makes TRD BBKs and the F-Sport brakes for Lexus. I'm personally leaning towards the StopTech Sport brake kit for my XB. It includes F&R PowerSlot rotors, Street Performance pads and SS brake lines for a little over $500.

 

Very few brake as conservatively as I do, so I wouldn't suggest myself as any kind of standard for drilled rotor use. In fact, a GM study of drilled Vs blank a few years back came out strongly supportive of drilled -- they very definitely provide benefits beyond appearance for street use. But the demarcation is clearly normal to quasi-normal use to hard use or beyond. Repeated heavy braking is very much not good for drilled iron rotors, go blanks instead and save a bundle of dollars !
FWIW -- drilled results in greater surface area for cooling (resulting in more rapid cooling), greater ease of water removal when wet, and more rapid pad grab -- so yes, a definite improvement for street performance. But as I've already clearly pointed out, if you repeatedly get heavily on the brakes, drilled doesn't make sense!

 

I love Google! I believe I hit the mother load of automotive brake rotor information here!

http://home.wavecable.com/~vtucker/A4/rotors.pdf

From the summary:




Since Power Slot rotors incorporate not only ball end milled slots in the rotor faces but also feature asymetrical curved cooling vanes, they should be ideal. However having recently discovered that virtually all brake rotors are now cast in China (thanks NAFTA!) I may just go with EBC USR rotors instead...



P.S., cross drilled holes in rotors don't actually aid brake system cooling by increasing surface area because the resulting loss of rotor mass negates any such benefit. They do aid in cooling on vented rotors by increasing airflow through the internal vane structure of the rotor. It has been shown that holes and slots both increase wet braking effectiveness but only during light brake applications. During heavy braking, any water between pad and rotor is effectively displaced by the braking pressure.



...

 

Hate to have to mention this, but the increase in heat dissipation area due to drilling compared to the loss of friction area due to drilling clearly places the cooling advantage on the side of drilling. However, given the scenario of repeated heavy braking, greater rotor mass is invaluable, hence my statement it makes no sense to go to either slot or drilled if the overall size of the rotor isn't increased (ie, big brakes). As I've already said, if you're not upgrading from OE sized rotors, then stick with blanks. If you're pretty much an every day driver, then you can be pretty much guaranteed much less pad life with slotted rotors -- is that what you want?

Still, I've spent far too much time on this thread and I'm tired of the contradictions. If you really give a ____, try reading through these threads (and links) and search for more of your own. It's not easy to find good info and every manufacturer has their pet opinion (big surprise, yes?) I stand by what I posted above, but frankly, like I'm really going to lose sleep over what the rest of you decide -- right ? Buy what you want to buy, that's the way the market works!

http://www.iwsti.com/forums/gd-braki...ed-rotors.html
http://forums.corvetteforum.com/c5-t...neer-test.html

Other miscelany:
http://auto.howstuffworks.com/auto-p...ke-rotors1.htm
http://en.wikipedia.org/wiki/Disc_brake
http://www.brakeworld.com/brembo-drilled-rotors.asp
http://www.importrp.com/zimmerman.html
http://www.pelicanparts.com/bmw/tech...Upgrade%20.htm
http://www.automotion.com/zimmermann...r-porsche.html

 

You didn't read my link did you?

I thought that you would be as excited as I was to finally find a very well researched, objective, scientifically based white paper on the subject of automotive brake rotor design. It even takes into account the GM study you previously referenced. Honestly, I would have been just as thrilled if it concluded that drilled rotors were best and slotted were worthless. I'm much more interested in the truth than being right.

Oh well, for the rest then:

 

Just a minor update and an apology for the fact that it doesn't pertain to BBKs. I've just learned that while EBC still claims to make 100% of the rotors sold in Europe, they also state that "a majority of the designs specific to the USA are also BRITISH made...but EBC like every brake manufacturer ....does need occasionally to buy some rotors in from approved sources to complete ranges in overseas markets". Since there isn't a single foundry left in the USA making rotor castings this means that US market EBC rotors might be sourced from Canada or more likely, China. If I'm going to get Chinese cast rotors I may as well get them from Power Slot, StopTech or Centric rather than paying a large premium for EBC rotors that may come from China as well. What a shame.

To help make up for the threadjacking, here is a link to a vendor that carries all of the non-TRD BBK kits available for the 2nd gen XB:

http://www.fastscions.com/Scion-xB2-Brake-Parts.aspx

I do wonder though how any of these front-only BBKs actually provide significant braking improvement while retaining the stock rear brakes without adversely affecting F-R brake bias. If I was in the market for a BBK I'd go with TRD but at least for now I think I'll settle for slotted rotors and performance pads.

 

I know that our front calipers are used on Lexus HS 250h not sure if that car has any options for bigger brakes, but it may be something to look at

 

Nope. Same brakes up front for the HS250H and the xB2.

 

If you want max stopping power for a good price, SS lines, and a set of ebc's most aggressive pads.

They might make a TON of brake dust, but you will stop on a dime.

 

I've been running Porterfield R4S pads and really like them. Low dust and I have a bit of stopping ppower.

 

ditto on just pads making a difference. I use the akebono ceramics, braking is greatly improved,but virtually no dust.

 

i just think the discs look wimpy inside my 18s, looks even worse on XBs i see with 19s. stopping power is fine as is for me..

 

The usual problem with ceramic pads is they eat rotors, but manufacturers like them because the light gray non-sticky dust isn't so noticeable as organic or semi-metallic pad dust. I almost went ceramic on my Eclipse, but after plenty of research, concluded semi-metallic was a better deal, better brake grip and much longer rotor life. 'Course, something's got to wear when applying the brakes, but it's cheaper to replace pads than rotors !

 

Meh. Rotors are cheap. I'd rather have to replace my rotors with my pads than have to continually clean all the nooks and crevices of my wheels.
My time has a dollar value.

 

I just drop down and wash the rims same time as I wash the rest of the car -- 'course, that's hand washing. Wish my time was worth that much, but good rotors are a lot more expensive than good pads as far as I can tell (though premium pads can definitely set you back, but I'm not road racing ). Rotor replacement is even more expensive with a dealer doing the work, and for most people, that's the situation.

 

Not all ceramic pads eat rotors. In general, the pads that produce the highest friction levels (and shortest stopping distance) are the pads that eat rotors. Centric has a great chart for brake pads with ratings for fade, friction, dust, noise, rotor life, etc.

http://www.centricparts.com/index.ph...269&Itemid=269

I ended up going with StopTech Steet Performance pads up front with Centric Premium blank rotors.