Do the cross drilled rotors really resist warpage? Is there a noticable difference in stopping power other than less heat? Thanks.

 

They are actually worse for braking performance than slabs. Primarily because, under heavy braking, they can develop stress fractures on the edge of the hole. For ultimate stopping power, get slotted rotors, and nothing more. The slots help evacuate gases created by the brake pad, ensuring a solid pad-to-rotor contact.

That being said, I have cross-drilled and slotted rotors on my car, but not for braking performance. I have them because they look cool, and that is the only reason to get drilled rotors. As long as you don't take your car to the track, you will not get cracks around the holes, and the braking performance is about identical to non-drilled.

 

The road racing guys cannot run drilled rotors. Probably has something to do with heat expansion.

 

I would strongly disagree. For all out roadracing cross-drilled rotors may develope stress fractures, but for anything else cross-drilled rotors will perform better than solid or slotted rotors.

Almost every major car manufacturer from Mercedes, Porche, BMW, Chevy (all ZO6 Vettes), Astin Martin, Lamborghini, Ferrari ...ect ALL use cross-drilled rotors on their very best vehicles. When the very best performance is desired, when production costs take a backseat to all-out braking performance, engineers at all these manufacturers install cross-drilled rotors as OEM parts. This is not for looks it is for the increased performance cross-drilled rotors provide.

Also keep in mind that virtually every hi-end brake rotor manufacturer from Brembo, AP Racing, Movit, Baer, Wilwood ..... All employ cross-drilling on their very best rotors. I can assure you the engineers that designed these rotors don't spec cross-drilling because it "looks cool".

 

There is a set of BAER Eradispeed plus on ebay for a c4, right now.

 

Back in 2004 when I purchased my 95, it has J55 brakes and I bought drilled slothed. The second I applied the brakes I noticed the effectiveness went away.

That is the reason I bought only slothed rotors for my CE LT4.

Yes, rotors with "both" look cool

 

This I found to be very interesting. "Warping" - is myth #1 in the linked article, BTW! As far drilled rotors go, just because some high-end car/brake makers use them may or may NOT have anything to do with braking performance as much as "bling".

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

I would look to racing or aircraft braking technology for the real answer: Truth or Bling? The "weekend warrior" track boyz 'round here do not use drilled rotors due to catastrophic rotor failures; solid or slotted is what they use. (I'd be curious as to what the GT1/2 Corvettes are using in the way of rotors.)

All that said, if ya want the Bling, then don't go cheap, for safety sake! And, at least some all-out tracker I hang with do it with solid or solid/slotted rotors to the exclusion of cross-drilled rotors. Of course they also have some pretty pricy brake systems - over all - including special purpose brake pads to go with them.

Bottom line: Apparently, nothing but the solid rotor is needed for even spirited driving on road course tracks, let alone the street, tho some also use slotted rotors. If there is a need for brakes beyond the demand of the local road course club racing - using solid or slotted (if that) rotors, then your application is truly beyond the practical experience of most on this board; point being, "NO HOLES" for anything street (is the conclusion I came up with when first considering "holes")

P.

 

not trying to jack this thread....what does the parts list look like for the c5 brake swap. And is there anything aside from the front rotors (13" I pressume) that you can stil use ?

to the OP
I just re-did mine and asked others who have more experience w/brakes than myself and was told the same regarding sloted and drilled. I was only interested as lately the price is reasonable and I had thought they helped cooling. My interests are to also be able to fit them using weld rims. I ended up using NOS rears rotors and some premium raybestos fronts (120. total), and chose to spend the money on better pads (hawk hps) and earl's lines.

 

For the most part, drilling: I'd put it about 90% bling and 10% value added function.

 

You can order a ready kit or you can order individual parts.

C4-C5 bracket with bolts
C5 Caliper bracket
C5 Calipers
C5 Rotors

Try Ebay

 

thanks for the info, that looks like a nice upgrade...I would want to know what (if any) work would be needed to clear 15" welds w/that assembly though.

 

While that may be true for high-end cars with high-performance braking requirements, there are big differences in those rotors and the ones sold by parts stores, eBay and others.

The "common" or parts store drilled rotors are drilled after the casting process. This drilling causes weakness around the hole. Extreme temperatures caused by repeated high-speed stopping will create cracks around the hole which leads to failure in the form of the rotor coming apart.

The high end rotors have the holes created as part of the casting process. All that has to be dome is the machining process of the rotor surface and chamfering of the hole at the surface. These rotors may also be heat-treated and will handle the extreme heat much better.

Road race teams do use drilled rotors; look at the Corvettes used at LeMans or the ALMS series. In fact most of the race cars at that level will have drilled rotors. But these rotors may be replaced after each event or maybe once during the event (LeMan as an example or even Daytona).

The holes in the rotor help to let air from brake cooling ducts pass thru the rotor face for a quicker cool down. Heat is an enemy of efficient braking and the holes do help as do the vanes between the rotor. But for general street use, the holes really don't do a lot as the rotor simply doesn't get that hot and street cars don't have brake cooling ducts and hoses.

If you want drilled/slotted rotors for the street, they will look but they should be checked occasionally for any signs of cracks around the holes. Once cracks form, the rotor can weaken and eventually fail at some point.

 

Don't mean to highjack this one further...but I have (for five years or so now) a $500 bounty on any proof of rotors with holes CAST into them.

So far; a lot of lookers, no takers. Nobody in the industry knows of this rare beast either. Yet (as here) we all hear about them. To which I say; show me. Must be Iron, pre machined, either a rough casting or a mold to produce it. Finished product has no merit and tool marks are obvious.

Careful please before you jump into this discussion, there's not much that hasn't been posted or talked about thus far. Including mold process, pics of molds, raw casting pics from Germany, etc. etc. None of which (including a major mfg who fessed up the final holes were drilled despite the vane structure) that has not been covered. Before someone yells Porsche, pull up their own literature which clearly sates "cross drilled rotors"...

----Open minded. Very skeptical still.

 

You can debate this subject forever but, to the Op's original question:

Cross drilled rotors will warp just as easily as any other rotor if the lug nuts are tightened unevenly or if the rotors are of poor quality or heavily abused in racing situations.

Generally, there is no noticable stopping power from a cross drilled rotor. Quality Brake Pads will make a very noticable difference in braking performance though.

 

First lets make some things clear, cross-drilled rotors are in fact almost always cross-drilled which is a machining process that occurs after the rotors are cast. As was correctly pointed out by Todd TCE. The only difference being properly cast rotors will be cross-drilled in areas that will not compromise the integrity of the disk or the pillar vain ventilation system built into the rotor.

I'm not avocating the use of cheap E-bay rotors, or blanks cast in the far east and then cross-drilled for looks without reguard to pillar vain placement or the thremodynamic properties of the blank. These rotors are definately not worth anything and will crack if pressed hard. Just like any other hi-performance part ~ you get what you pay for.

 

In the end one could say that the rotors with the groove in them is a step up from factory and offer better stopping power for someone wanting a slightly better stop, right?

 

They won't hurt anything. Transform your car into a fire breathing monster; nope. Notice the difference when driving all other things the same; nope. Greater pad wear; yup. More dusting; yup.

One could argue that they maximize pad aggressiveness thus enhance their performance value to all they'll ever be.

 

If you want better stopping power from your stock brake system, install Hawk HPS brake pads and you'll really notice better braking performance!

There's no reason to install cross drilled or slotted rotors on a daily driven vehicle other than for looks.