Ok Guys now I am all confused. Dark-Knight they look great.
Lancer003 That looks bad.

 

So, what is the difference between the 2? Is it the brand only, driving conditions, what?

Lancer003, what is the MFG on those?

 

It's my understanding that rotors which have been drilled will crack. However, there are a few manufacturers (and unfortunately, I don't remember who they are) who cast the holes in the rotor when it's being made rather than drill it later and these rotors won't crack any worse than undrilled ones.

Could be wrong. Don't claim to be an expert; it's just what I've read.

 

Cast holes are better than drilled holes. no holes are better than either. The hole is a stress point on the metal no matter how you put it there. I've got a set of OEM Porsche rotors (cast holes) sitting in my garage right now with cracks coming from the cast holes.

On a street car, drilled rotors are fine, but recognize them for what they are, a show mod, not a performance mod. The pictures I posted are from cars used on a road course. I don't remember what brand

 

So if you drag race & auto-x, who's slotted rotors are 'safe' to buy?

 

Drag Racing doesn't really stress the brake system that much. It's not 1 hard stop that is hard on the system, it's braking hard over and over that really does it. for a dedicated 1/4 mile car, it'd put on a set of those titanium blades that look like they're made for motorcycles just to save weight. For a street/srip car, if it works on the street, it'll be fine for 1/4 mile

AutoX is only a little worse the street driving. Yes you're on your brakes hard, but only for a minute or 2 so you're brakes don't have time to get really hot. I would simply stay away from drilled rotors. You may also have to worry about what class you're in and aftermarket rotors can bump you up into a higher class if you are trying to run in a stock class.

For serious road course work, look at what the professionals are using.
- This is Gary Hoffman's new setup. I think he's only got them in C6Z sizes now, but hopefully more sizes will be coming soon.
http://forums.corvetteforum.com/show....php?t=1440393
- The LGM World Challenge cars use StopTech aerorotors
http://www.lgmotorsports.com/catalog...oducts_id=1398
(note that these are different than the stoptech replacement rotors (http://www.lgmotorsports.com/catalog...oducts_id=1542)
- You can get Bear Eradispeed rotors w/o the holes
- Slotted only Wilwood Rotors
- 2-piece rotors are better,
- 2-piece floating rotors are the best, but they will make some noise on the street.

At the end of the day, it's hard to beat the value of the NAPA replacement rotors for ~$25 each. Yes, they wear out faster than the high end rotors, but at that price, it's easy to afford swapping them out all the time and keeping spares on hand.

Whatever you use, it's wise to keep you eye on them. If you see minor surface crazing, that's no big deal. If you see little cracks on the surface really start to watch them. If the cracks reach the edge of the rotor or go from hole to hole, replace the rotor.

 

Well said!

 

Thank you for taking the time to write all of that helpful information down!

 

The holes are not for show either on the track or off the track. They reduce temperature and temperature reduction is a good thing. They also help with water evaporation, and that's a good thing too. If the holes didn't reduce temperatures over 90 degree F, or aid with water evaporation then they'd be for show.

According to PCNA the holes are "drilled".

 

try http://www.corvettegarage.com
ask for Nate tell him "Gil sent you"
mrgil

 

Have over 10K miles on mine. Luv 'em.

 

Based upon Lancer's post, serious race drivers ignore Porsche's findings. Bottom line: If you want the best, go slotted only. Holes reduce the total braking surface area and are prone to cracking. If you want cheap rotors that need to be replaced often, go with NAPA.

 

I'd say the Porsche 917 and GT1 Le Mans race cars were driven by "serious race drivers", and they had cross drilled discs. And BTW, Porsche GT3 Cup cars also use cross drilled discs, and these cars are obviously dedicated...serious...track cars.

Porsche knows brakes...

 

exactly, so what if they run cooler if they don't last long enough to finish the race.

1510'F vs. 1600'F: they're both hot as hell, WC, ALMS, Trans Am, NASCAR, FIA GT1,2,3 all use either slotted or blank rotors

I have also read conflicting studies that show drilled rotors run hotter. I didn't bring it up before because I don't remember specifics or have a link, but basicly less metal has to absorb the same about of energy so they're hotter.

Wilwood publishes a warning about Drilled rotors, I'll look it up and post it when I get a chance later today

 

I'm willing to bet that the rotors Porsche uses in LeMans are not only unavailable to C5 owners, but are as different from the $100 Brembos as a mini is different from a 911. For the real world, drilled rotors that are purchased for under $150 each should NOT be tracked, IMO. Making the average Joe think that his $50 or even $100 drilled discs are "racing" discs is dangerous, at best!

 

So are you saying serious race drivers ignore Porsche's findings or not??

As for "availability", Porsche took the cross drilled discs from the 917 and used them on production 911's. This is the kind of stuff they do...validate the product/system at the race track...then move that product/system to their street cars.


Quality cross drilled discs provide improvements in both fade resistance and water evaporation. If someone buys cheap imitations, they're getting what they paid for.

The issue here is 1) Does cross drilling (quality engineering and quality parts) provide improvements, or is it for "show", and 2) Does Porsche know anything about brakes.

 

I've never heard of Porsche LM cars using cross-drilled, or ANY pro team for that matter, but I have to admit I don't know for sure for Porsche. I know the WC, Corvette LM team and many others never use x-drilled. They're typically notched or slotted or blanks.

Regardless, consider this, like Dave says, they are likely not the same quality available to the general public. Ignore your statement about cheap imitations... how much does a LM team pay for rotors? We're not talking $100 vs. $150 here...

Second, and this is well known, that drilled rotors don't crack when hot, they crack when they cool. If you're a race team, who gives a crap, they're on for one race anyway. If you're an individual tracking on weekends you can't and don't want to refresh every piece each weekend.

So let's be honest here. Comparing our setups to $M budget Le Mans teams is apples to oranges. It's like the old argument that Formula 1 uses traction control so so should we.

We should be looking to the mid-level pros (LG WC, T1 etc. etc.) to understand what setups are best for our cars when we track.

When it comes to street only, get whatever the heck you think looks prettiest because if your driving hard enough to notice any difference you're driving to damn hard for the street.

 

I'm sure they do, but by you're all or nothing logic all the other teams must know nothing...

 

As Promised:

From: http://catalogs.wilwood.com/_pdf/_tech/Rotors.pdf
pg 131.

from: http://www.stoptech.com/tech_info/faqs.shtml#15

 

Porsche took the brakes directly off of the 917 race car and used them for their production 911's.

The 996 and 997 GT3 Cup racers are available for sale to the general public, and they have cross drilled discs.

/////////////////////////////

The issues I responded to dealt with cross drilled discs being 1) "for show", and 2) not offering any performance benefits. They are certainly not just for show, for the reasons I stated. Additionally, a panic stop from 10 mph over the posted Interstate speed limit (80 mph), or continual use of the brakes coming down a steep mountain road, generate enough temperature where fade could be a problem for standard brakes. The real world benefit of aiding in water evaporation is also certainly a "street driving" benefit.