Slotted Rotors?

[Red V6 Raider]

I'm always keeping my eye on eBay for any good deals and I constantly see slotted or crossdrilled rotors for very cheap. I probably would have a picked up a pair by now except that they only come with the front rotors. I'm wondering where I could pick up slotted rear rotors seperately, anyone know? Also, if anyone has heard bad things about rotors from eBay, lemme know please.
-THANKS

[ June 10, 2002: Message edited by: FirebirdGT ]</p>

[jmorgan]

any place that sells front slotted rotors has rear sloted rotors too ( i would get front sloted first they do most of the stoping)

[FirebirdGT]

Question - why do you want slotted or cross-drilled rotors?

[Patrick Javert]

looks and cooling. the rotors won't warp, but they may crack since drilling causes stress points.

[FirebirdGT]

<blockquote>quote:</font><hr>Originally posted by Patrick Javert:
looks and cooling. the rotors won't warp, but they may crack since drilling causes stress points.<hr></blockquote>

Slotted or cross-drilled rotors were never intended to provide any form of cooling, only control of pad out-gassing which they don't do anymore.

[Red V6 Raider]

I want them probably mainly because they look good and they have really good stopping power. And I think I need to pick up some new rotors anyway so I figured might as well get some rotors I could consider an upgrade.

It would just be for street use. It's not that I NEED them but I kinda want them. Here's two of the auctions I was looking at. They're usually just auctioned one after another so there's not any rush.

http://cgi.ebay.com/ebaymotors/ws/eB...tem=1834855475

http://cgi.ebay.com/ebaymotors/ws/eB...tem=1834584483

What do you guys think?

[Red V6 Raider]

Ummmm...why don't they do it anymore?

[black98V6]

had to do with asbestos in the pads.. as the pad heated up there would literally be a layer of gas develop between the pad and the rotor.. of course if you have a cushion of air between those 2 surfaces you aren't going to do much stopping.. slots and holes were put in place to exhaust those gasses..

[ June 06, 2002: Message edited by: black98V6 ]</p>

[Dominic]

they help in rain-braking, most motorcycles come with them, so do porsches and ferraris... hmmm old technology eh?

[FirebirdGT]

If you want the "Look" then get either, but unless you're racing they're not worth the extra money. Slotted are DESIGNED to wear the pad to keep it clear and fresh during racing. If you want to keep replacing pads, go for it. Cross-drilled do nothing for performance, other than DECREASE the amount of rotor/pad contact. I personally want as much as I can get, which is why I upgraded to the larger LS1 brakes. I see no reason to have "swiss cheese" rotors.

[DominusEtDeusNatus]

I'm going to have to agree with Robert on this one. I see some of you are experts in braking systems.

The brakes function by converting the kinetic energy of the car into thermal energy during deceleration, producing lots of heat, which must then be transferred into the surroundings and into the air stream.

The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for race cars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000deg F the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.

Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed.

Slotted and/or drilled rotors have less or more contact area then regular ones? Also would slotted and/or drilled rotors have greater or lesser resistivity to heat dissipation that can cause premature cracking from thermal stress? Have you guys seen the Nascar rotor camera? They get red hot in less then 1 sec. They're not even stopping, they're just slowing down a bit for the turn. Plus their rotors are made specifically for racing and high speed braking. Your rotors are made for slow driving. Do a few hard stops and you will see increases in stopping distance. Your brakes haven't had time to cool off yet. They will get soft and respond slower and slower. Now take away 30-40% of the braking and heat storage capacity away. Once the brake fluid inside the caliper has boiled, it has lost a significant percentage of its original boiling point and should be replaced. Yes, it only takes one time.

For many years most racing rotors were drilled. There were two reasons - the holes gave the "fireband" boundary layer of gasses and particulate matter someplace to go and the edges of the holes gave the pad a better "bite".

Unfortunately the drilled holes also reduced the thermal capacity of the discs and served as very effective "stress raisers" significantly decreasing disc life. The advent of carbon metallic friction materials with their increased temperatures and thermal shock characteristics ended the day of the drilled disc in professional racing. They are still seen (mainly as cosmetic items) on motorbikes and some road going sports cars. Typically in original equipment road car applications these holes are cast then finished machined to provide the best possible conditions by which to resist cracking in use. But they will crack eventually. Slotted rotors will fill up with pad material, when the system is operating at too high a temperature.

DOT 3 and DOT 4 brake fluids are ether based and are hygroscopic in nature - i.e. they absorb water vapor. As the braking system in not quite airtight, a significant amount of water can be absorbed from the atmosphere in the course of a year. A 3% water content in brake fluid drops the boiling point as much as 170 degrees F. Brake fluid should be completely replaced annually.

Carbon metallic: This is a trademark of the Performance Friction Corporation. Pad friction compounds containing large percentages of pure carbon along with various metallic elements. Pioneered by Performance Friction Corporation these compounds offer very constant coefficients of friction vs. temperature characteristics along with increased thermal capacity. The disadvantage is that, since they both operate at higher temperatures and their temperature rises to operating temperature faster than other compounds, they increase thermal shock to the disc and increase thermal conduction to the caliper pistons and brake fluid. As a result, it is recommended to not use drilled discs with carbon metallic pads.

Some of you claim that since Porsche and Ferrari use drilled rotors, so for that reason alone they must be better.
From the Porsche source:" A special ventilation system cools the entire braking system using air routed from inlets at the front of the car, thereby ensuring consistent levels of performance and greater longevity, even under the heaviest use. " Do you have a special ventilation system in your camaro to cool your drilled brakes that now require extra air to dissipate heat? The only advantage to cross drilled rotor is the circulation of air, but when there is no air ducts there is no air to circulate.

From Ferrari source:"These brakes are extremely expensive as they are made from hi-tech carbon materials (long chain carbon, as in carbon fibre) and they can take up to 5 months to produce a single brake disk. The first stage in making a disc is to heat white polyacrylo nitrile (PAN) fibres until they turn black. This makes them pre-oxidised, and are arranged in layers similar to felt. They are then cut into shape and carbonised to obtain very pure carbon fibres. Next, they undergo two densification heat cycles at around 1000 degrees Celsius. These stages last hundreds of hours, during which a hydrocarbon-rich gas in injected into the oven or furnace. This helps the layers of felt-like material to fuse together and form a solid material. The finished disc is then machined to size ready for installing onto the car." Can you afford these rotors or are you buying cheap rip offs that are just drilled and were not made for it in the first place?

Summary for car rotors.

These rotors that you are buying are just standard rotors that are drilled full of holes. The structure is weakened and the mass of the rotor is reduced, therefore limiting its ability to deal with heat buildup. Ferrair and Porsche on top of their air ducts have their rotors designed at the casting stage to be cross-drilled. They have thicker rotor surface sections and more material in the cooling slots. They are stronger to begin with so they will hold together longer despite the cross-drilling. Do you have any idea as to cost of their brake systems? I could sell my car and still not afford their rotors. But of course the $100 special from some vendor that knows nothing of braking will yield simial results. Keep dreaming.

Slotted rotors will increase pad wear. Just think about this one so I don't have to explain it.

Yes, bikes can afford to have cross drilled rotors because they weigh 400lbs, not 3400lbs. My car is around 3000lbs now and I can already notice a huge difference in braking power from when I was stock weight. I can only image how much less rotor would I need to stop if I dropped another 2600lbs. On top of that bike has 2 rotors and I have 4. And you dare to compare the two? On what basis? And lastly their brakes are probably made just like I stated above, with cross drilling in mind. Not solid that were later cross drilled. It helps with stopping in the rain. On bikes it doesn't matter since there is plenty of stopping area. Those that say bikes have them so they must be good, have you ever rode a bike? I have many times. They stop on a dime. You can't even realize the stopping potential due to tires being the weak point.

Alright I said enough. Lot of quotes above from braking specialists not people who just sell them.

[Blue94V6]

If anyone is really bent on having cross-drilled or slotted rotors Brembo makes a braking system for 98+ camaros that cost $2,995. Brembo does or has manufactured brakes for Mercedes, BMW, Porsche, Ferrari, and as far as I know they are standard equipment on all Lamborghini's. The product description mentions a "floating disc" which "reduces heat related stress".

P.S. Thanks for all the great info Dom

Blue 1994 3.4l 5spd
Eibach Springs
KYB Gas-A-Just shocks
K&N Filtercharger

[coburnaburna]

Re: Slotted Rotors?

I think The word your looking for is Frisbee (blue). This is the only type of floating disk that would be worth buying for our cars. Slotted or drilled rotors are pointless besides for looks. Even if you like the looks of them your wallett is not because of glitches in them. Oh yea, we also have v6's so there is absolutely no need in them if the ls1 doesnt come with them standard.

[RyanAndyBob]

Re: Slotted Rotors?

Dude dont let ppl rip on your opinion like that. I bought mine off ebay and got performance friction brake pads andpainted my calipers. looks real nice. Definite improvement in stopping. go for it.

Oh yea i bought mine as a set of 4, because it was cheaper to buy them together than seperate.

[98 3.8]

Re: Slotted Rotors?

Dude dont let ppl rip on your opinion like that. I bought mine off ebay and got performance friction brake pads andpainted my calipers. looks real nice. Definite improvement in stopping. go for it.

Oh yea i bought mine as a set of 4, because it was cheaper to buy them together than seperate.

Did you not read the thread? Drill/slotted/dimpled/whatever = looks...NOT performance.