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If it's looks that you are after, go for it, but I don't think there's much of any performance to be gained. Don't worry about minor cracking. I owned a set for many years, and was told by the manufacturer that they all crack, and it's not a problem unless you see the cracks go completely from hole-to-hole. Mine never even came close to that, and I raced autocross and drags regularly. Minor stress-cracking is OK.

Don't be too concerned about "hear-sayers". There's pleny of those in these-here parts. Another forum member maybe summed up cross-drilled rotors best, something along the lines of "There's two opinions coming from two types of folks: those that OWN cross-drilled rotors, and those who haven't". I think you'll find that most guys who actually have owned were happy with them.


:cheers:

 

Don't confuse racing equipment with street equipment. Racing teams change their pads after every event, (bad cases during an event). That will be in most races less than 500 miles. You want to do brake jobs every month, then go right ahead. Also, racing brake systems only work at extreme temps. Your street driven car is designed to work in mostly cool temps. Carbon brakes don't work so good cold. Talk to Lou Gigliotti about that stuff or David Farmer or other road racers. Also, race brakes squeal like a pig no matter what the temp is. Listen to the race cars come to a stop in the pits.

 

Phil & Bogus,

Nobody denies that many racers use drilled and slotted rotors. In fact, that is precisely where confusion begins for the typical consumer. Massive race rotors are properly designed, cooled and sized to withstand the rigors of a single race. If their setup was grafted to your car, you would be truly satisfied from a performance perspective & no doubt they would outlast the OEM setup. But make no mistake, it ain't just a rotor swap and racers are not running $500/pr C4 Eradispeed's or any other premium wannabe lookalike aftermarket rotor that fits the OEM brake system. Any resemblance...& the presence of holes, dimples and/or slots is purely coincidental. Heavy demand from waxers is driving sales of OEM size rotors with a machined surface. These rotors are compromised from a durability perspective, compared to bland rotors. Braking capability with the OEM configuration is largely a function of pad compound, brake ducting and fluid freshness and type. Rotor machining has little effect aside from decreasing longevity and offering "looks".

That said, any mfr that does not sell what customers demand is missing an opportunity. The educated consumer will separate hype from fact by either running dozens of rotors on-track or by speaking with those who did. The answers about rotor performance lie in the forum's Racing Section.


[Modified by Rick93Z07, 8:01 AM 2/21/2003]

 

Exactly :withstupid:

I know this becomes a heated battle everytime it comes up but I have a few points of my own to give on the topic. Saying this I am not an engineer or autocross/racer with 1000's of miles under my belt but there are some obvious reason I believe that the Cross drilled rotor when made correctly can only help braking performace.

When looking at the actual race cars that use them the facts are that they use DO them. Then you must look at the cars that come OEM with them. Porsche and Mercedes too name a couple put drilled rotors on their cars from the factory. I think many will agree that the stock Porsche braking systems are the best in the world. This is an art Porsche had been perfecting for many years so I would have to think that they know what the heck they are doing.

This is all my opinion but I can say it is based on some good duductive reasoning and my experiences actually driving these cars, albeit not in a full race situation but hard driving for extended periods of time.

All being said, don't drill your stock rotors, they will crack. Buy a good quality set like the eradi's or Zimmerman's(which make cast-in holes on their drilled rotors for all the euro marks) and save your self the problems associated with low quality knockoff's

:flag

 

What about the dreaded condition known as OUTGASSING! Do not rotors need something to releive the pressure? All the sales litature impresses the need for vent holes to releave the gas. Take nature for example, just think of the catastrophic consequences if we did not have a vent hole.

 

$500 Eradispeed 2pc rotors to fit a stock C4 brake system are not like those on a 911 Porsche. No feed-through casting holes to my knowledge. A front-engined C4 with a cast iron motor will not have the braking of a Porsche even with Big Reds & fingers crossed anyway. Corvettes abuse brakes.

Baer's claim to fame is OEM fitment & 2 pc construction with reuseable center hats and $300/pr replaceable disks. I watched a fellow burn a pair to thumping, visibly cracked "ruin" in five 25 min sessions...1-1/2 days. Baer was "sorry" & offered free shipping but no warranty on the replacements. My OEM's easily last over 5X longer under identical duty. Driving styles vary, but I was not impressed. If you want better braking performance and you've already addressed cooling ducts, pads and fluids, you must install bigger/wider brakes such as the $700 C5 conversion. The wide $60 C5 GM rotors will make the C4 Eradispeeds pale in comparison. Cap head screws, curved vanes, "thicker cheeks" and pretty paint will not substitute for rotor width. Thicker cheeked rotors will absorb more heat, but their constricted vents impede cooling. Under extended severe duty, cooling and venting become more critical, so thicker cheeks have major drawbacks. The center vent in a wider C5 rotor is huge in comparison. Baer C4 products do not defy thermodynamics and they are not made of krypton. If you want better braking, go with bigger brakes, not expensive componentry to fit the marginal OEM system.


[Modified by Rick93Z07, 5:01 PM 2/21/2003]

 

Porsche themselves say that the only reason their cars' rotors come with holes in them is to help braking in wet conditions. They say nothing about them performing better than solid rotors.

Also, having drilled rotors to prevent outgassing is a solution to a problem THAT NO LONGER EXISTS. Sure, with crappy organic based pads 30 years ago this helped. But with today's carbon and metallic brake pad technology, this is not happening. Large, solid rotors will provide you with the best possible stopping. The large (and THICK!) and solid rotor is there to have a large amount of mass to take in the heat produced from braking. Then, when you are finished braking (straightaway, etc) the rotors can cool and the next time you stop, they absorb more heat. The more mass your rotor has the better it will allow you to stop (the more heat it can absorb). Drilling the rotor (or having holes in it) reduces mass and takes away from the rotor's ability to absorb your braking heat and hinders your stopping abilities.

Disbursing the heat absorbed is secondary (so don't make an arguement about them cooling better, etc). The primary brake function is to STOP THE CAR. If the rotor cannot absorb anymore heat you overheat the brakes and you don't stop. Cooling the brakes is secondary, AFTER YOU STOP THE CAR.

Just buy solid rotors for performance, ones with holes in them if you like that look....

 

Theres sure been a lot of good techie input in this thread. I had no idea I would be (unknowingly) starting such a food fight though, lol. Thanks for all the good info guys :blueangel:

 

The key to getting drilled rotors to last is to have them cryo'd, use the right pads for the type of driving you're doing and keeping them as cool as possible (ducting to the rotor). You can buy rotor heat paint that will tell you how hot your rotors are getting.

I've used diversified http://www.diversifiedcryogenics.com/ to cryo all my drilled rotors and their work is first rate (just ask the Porsche GT3 owners at any ALMS event). Minor cracking is a non event - only when you get cracking extending from hole to hole do you need to replace the rotor.

There's been a lot of discussion of this thread about Porsche drilling rotors. Porsche OE rotors, ususally made by Zimmerman, have the hole pattern cast into them - not drilled. As an old "Porschephile", Porsche is an engineering company first and if it doesn't improve the vehicle they don't do (they've been using drilled rotors since the 917 days). Even the new carbon rotors that are now an option ($10,000 upgrade) are drilled.

Drilled rotors for the street is just a "Looks Thing" as it's not really necessary INHO. If you're braking hard/long enough on the street to need drilled rotors I hope I'm not coming from the other direction toward you.

 

Where can you get a 13" upgrade for $550. Cheapest I've seen is around $800.

 

http://www.superchevyperformance.com...s/gsbrakes.asp

$594.75 including everything with J55 calipers and pads, GS rotors and all hardware)

$675.38 including everything (GS calipers, brake pads, rotors and all hardware).

Toni

 

I bought a set of 13" PowerStop cross drilled rotors for my 96......they are only $200 for the set and they work better than the stock ones and look great too.......getting a set for the rear axle this spring too........ :hurray: