[tracktone01]

I found this auction on Ebay earlier today. $299.99 for all four rotors for the 300 and $339.00 for all four for the 300c! Just wanted to know what you guys think: 300 and 300c Cross-Drilled Slotted Rotors

I emailed the seller and this is what he had to say:

Thank you for your interest in R1 Concepts. Sorry, but you did not specify if you had the 300 or 300c. Nonetheless, I will provide you with the price for both vehicles. We will offer you $299.99 for all four rotors for the 300 and $339.00 for all four for the 300c!

The rotors that you are inquiring about are cross-drilled and slotted. They are Electro-plated black on the hubs and inner vents to prevent the rotors from rusting.

These are premium quality rotors made from stronger casting than other rotors that are on the market. We can provide you with three different types of styles: drilled, slotted, or combination of both.

Please let me know what you guys think of this deal.

 

[DZeckhausen]

I found this auction on Ebay earlier today. $299.99 for all four rotors for the 300 and $339.00 for all four for the 300c! Just wanted to know what you guys think: 300 and 300c Cross-Drilled Slotted Rotors

I emailed the seller and this is what he had to say:

Please let me know what you guys think of this deal.

Regardless of the price, you don't ever want to cross-drill AND slot a set of rotors. One or the other, but not both. All it does is weaken the rotor, without providing any additional benefit.

For a car which will never be taken to the track, cross-drilled rotors are fine. They give you improved bite, reduced delay of braking in wet conditions, and you save up to 1/4 pound per rotor over plain or slotted. For track use, you should go with slotted. Under race conditions, drilled rotors will crack sooner than plain or slotted rotors. Slotted give you virtually the same improvement in initial bite as drilled, without the propensity to crack under tough conditions.

Getting back to this vendor - you might want to ask him where these rotors are manufactured. I suspect they are cast in Mainland China or Taiwan. There are a handful of decent foundries in Asia, but most of them are boutique foundries with dirt floors, no process control, no adherence to standards of quality, and they crank out total junk. For example, I've seen casting flash completely block airflow through some cheap Asian rotors. If he says they are made at in ISO certified foundry in Asia, ask him the name of it. If it really is a quality foundry, he won't be afraid to identify it by name.

 

[tracktone01]

Thanks DZeckhausen! I'll email him right now and ask him those questions. Hopefully, he'll respond today. I'll let you know what he says.

 

[kidcoastal]

Regardless of the price, you don't ever want to cross-drill AND slot a set of rotors. One or the other, but not both. All it does is weaken the rotor, without providing any additional benefit.

For a car which will never be taken to the track, cross-drilled rotors are fine. They give you improved bite, reduced delay of braking in wet conditions, and you save up to 1/4 pound per rotor over plain or slotted. For track use, you should go with slotted. Under race conditions, drilled rotors will crack sooner than plain or slotted rotors. Slotted give you virtually the same improvement in initial bite as drilled, without the propensity to crack under tough conditions.

Getting back to this vendor - you might want to ask him where these rotors are manufactured. I suspect they are cast in Mainland China or Taiwan. There are a handful of decent foundries in Asia, but most of them are boutique foundries with dirt floors, no process control, no adherence to standards of quality, and they crank out total junk. For example, I've seen casting flash completely block airflow through some cheap Asian rotors. If he says they are made at in ISO certified foundry in Asia, ask him the name of it. If it really is a quality foundry, he won't be afraid to identify it by name.

Great post Dave. I was wondering the same thing... which was better.

 

[todd tce]

I generally agree with Dave on that. But for the most part buyers WANT slotted and drilled rotors. If one is good, then both must be better....And thus most offer it as a combo finish because it's market demand. Not because one is better or worse.

I was looking at the rotor pic supplied....funny how it looks exactly like the same castings I have sitting on the shelf. Right down to the balance mill work and numbers on it. No way of knowing if what the guy sells you is a factory part modified but I'll wager $20 the ones in the pic are bone stock items.

More over I'd be very interested to hear from a buyer who has them in hand BEFORE you put them on the car I have a question about them. I'm not going to post it now to ask the vendor, but if you buy them let us know when and I'll take 10m of your time. Oh, we'll post the q&a here after too.

 

[DZeckhausen]

I was looking at the rotor pic supplied....funny how it looks exactly like the same castings I have sitting on the shelf. Right down to the balance mill work and numbers on it. No way of knowing if what the guy sells you is a factory part modified but I'll wager $20 the ones in the pic are bone stock items.

I would prefer a modified factory part to a cheap casting manufactured in a Mainland China boutique foundary with a dirt floor and chickens running around.

 

[shanemcse]

I just picked these up in person. I have them if anybody has any questions. They are very nice and from my point of view much better than others I saw on EBAY and the internet for the price. Others I saw only had 4 or 6 slots cut with 4 or 6 rows of holes. These have 8 lines and 8 rows of holes. I don't know a lot about rotors but I figure the more holes and lines cut the better. I live close by so I was able to go down and pick them up in person. The people I talked to on the phone and at the site were very helpful and the guy that helped me was a 300C owner himself.

 

[DZeckhausen]

I just picked these up in person. I have them if anybody has any questions. They are very nice and from my point of view much better than others I saw on EBAY and the internet for the price. Others I saw only had 4 or 6 slots cut with 4 or 6 rows of holes. These have 8 lines and 8 rows of holes. I don't know a lot about rotors but I figure the more holes and lines cut the better. I live close by so I was able to go down and pick them up in person. The people I talked to on the phone and at the site were very helpful and the guy that helped me was a 300C owner himself.

You need to look back at Post #2 above or click on this link: http://www.300cforums.com/forums/109345-post2.html

Repeat after me: Rotors that have been slotted AND drilled are bad!

If a vendor is clueless enough to drill and slot rotors, then you can be reasonably certain they don't know the proper drilling or slotting patterns to apply to maximize the benefits while avoiding structural damage to the rotors. And no, more holes and slots is not better than fewer holes and slots! You want the hole pattern to be such that the entire surface of the pad is swept by them. To do this, you need the holes in adjacent rows to be staggered. You also need to space the holes appropriately, such that they don't cut into any internal cooling vanes. And you don't want the size of the holes to exceed 4mm in diameter.

Here's an example of drilled rotors done properly:

Note that the spiral "arms" of the drill pattern can run in the same direction or the opposite direction of the internal cooling vanes. It is critical for the spacing of holes to not hit or come too close to the internal vanes. You can see this in the cut-away photo above.

Slotted rotors should be cut in a direction opposite to the internal vanes so that each slot is supported by several vanes, which act as reinforcement. You should NEVER slot the rotor in the same direction as the internal vanes, since this dramatically weakens the rotor. Since the vanes should lean toward the back of the car at the top of the rotors, the slots should tilt forward in the opposite direction. The slots should never be machined all the way to the outside edge of the rotor. If they do, the rotor can crack under heavy use.

 

[4herb2tas0tik]

hey DZ thanks for the insight...i just learned something new..

 

[Goose]

On that note, where can we find a good set?

You need to look back at Post #2 above or click on this link: http://www.300cforums.com/forums/109345-post2.html

Repeat after me: Rotors that have been slotted AND drilled are bad!

If a vendor is clueless enough to drill and slot rotors, then you can be reasonably certain they don't know the proper drilling or slotting patterns to apply to maximize the benefits while avoiding structural damage to the rotors. And no, more holes and slots is not better than fewer holes and slots! You want the hole pattern to be such that the entire surface of the pad is swept by them. To do this, you need the holes in adjacent rows to be staggered. You also need to space the holes appropriately, such that they don't cut into any internal cooling vanes. And you don't want the size of the holes to exceed 4mm in diameter.

Here's an example of drilled rotors done properly:

Note that the spiral "arms" of the drill pattern can run in the same direction or the opposite direction of the internal cooling vanes. It is critical for the spacing of holes to not hit or come too close to the internal vanes. You can see this in the cut-away photo above.

Slotted rotors should be cut in a direction opposite to the internal vanes so that each slot is supported by several vanes, which act as reinforcement. You should NEVER slot the rotor in the same direction as the internal vanes, since this dramatically weakens the rotor. Since the vanes should lean toward the back of the car at the top of the rotors, the slots should tilt forward in the opposite direction. The slots should never be machined all the way to the outside edge of the rotor. If they do, the rotor can crack under heavy use.

 

[marlinspike]

Slotted rotors should be cut in a direction opposite to the internal vanes so that each slot is supported by several vanes, which act as reinforcement.

What are your thoughts on ATE powerdiscs where the slots sorta go all over?

 

[Meister]

I just picked these up in person. I have them if anybody has any questions...

Please give us your impressions after installing them.

And if you're not aware of it, the best brake bedding "how to" I've seen is posted on Dave Zeckhausen's Web site. Check it out and bed 'em in right.

 

[DZeckhausen]

What are your thoughts on ATE powerdiscs where the slots sorta go all over?

The ATE Powerdisc rotors with the "mutipurpose groove", for those who haven't seen them, use a unique slot pattern that resembles an atom with orbiting electrons. These are often referred to as the "nuclear rotors."

The steep angle of the grooves and the fact that they make these only for rotors that are non-directional (meaning the internal vanes point straight out from the center of the rotor and there is no "left" or "right") ensures that the rotors are not weakened by a slot running in the same direction as an internal vane.

The Powerdisc pattern is an attempt to break out of a commodity market with something that is recognizable, not only by the packaging, but also once mounted to the car. Brake dyno tests show no significant advantage in bite over traditional slotting patterns, so the "atomic" pattern is nothing more than a marketing gimmick.

Since ATE doesn't use a Dacromet coating like the OEM factory rotors, these tend to rust in the grooves, in the internal vanes, in the center hub, and any other unswept area, often causing an orange "ring of shame" that is visible with open wheel designs. Not the sort of thing you want on a show car.

 

[shanemcse]

I was going to take a picture of them and post it but the picture in the 1st post is exactly what they look like. Irotors.com does offer different designs either with all holes or with all slots. I just don't believe having holes and slots is a bad thing. If it was a bad idea then why do so many places offer them?

For example here are some pretty popular sites that offer rotors with holes and slots.

http://www.tirerack.com/brakes/brakes.jsp?make=PowerSlot&model=ProStop+II+Rotor

http://baer.com/cgi-bin/htmlos.exe/0097.3.1847063509000004772

http://www.nationalfleetparts.com/rotors.asp

I am not trying to argue but I just would like some kind of proof seeing how so many places offer them.

 

[steve 300c]

Its starting to smell like a group buy in here! :wink1:

 

[Meister]

...I just don't believe having holes and slots is a bad thing. If it was a bad idea then why do so many places offer them?

For example here are some pretty popular sites that offer rotors with holes and slots.

http://www.tirerack.com/brakes/brakes.jsp?make=PowerSlot&model=ProStop+II+Rotor
...

I am not trying to argue but I just would like some kind of proof seeing how so many places offer them.

Hi shane. I'm here to learn, and very much appreciate you and the information you're sharing. So don't take anything I say here as being argumentative, or worse. Because it's not.

This forum is "blessed", if I can use that word here, to have one of the brake industry's foremost wizards in close attendance, Dave Zeckhausen of Zeckhausen Racing. He's "in the trenches" with racers from all aspects of motorsport on a regular basis, sees the effects of good & bad design on a near-daily basis, and is bright enough to make pertinent application of this "insider" information.

So if I'm going to be setting up a car for racing, Dave's word is gospel for me - his credibility is sky high. I need no second opinion.

So I suppose the question is, how closely do I need to follow what Dave knows to be best for track applications if I'm only going to run my car on the street? For me, the answer is probably 100%, because of my God-given wild hair that I'll never outgrow...I manage to find sections of road that enable me to put my 300C through its paces in a very demanding manner with some regularity. For others, it may be less crucial.

It's interesting, shane, that your very first reference, the one from Tire Rack, supports Dave's findings by offering a faux drilled, slotted rotor, since cross-drilled rotors, especially when combined with slotting, tend to crack. The "holes" are merely cosmetic dimples in the rotor's surface. Here's the short version of that product description:

From Tire Rack:
http://www.tirerack.com/brakes/brak...roStop+II+Rotor

"It’s a fact that venting the gas emitted by hot brake pads improves overall brake performance and helps minimize fade. At one time the conventional wisdom in racing circles was to cross-drill brake rotors to aid cooling and eliminate the gas emitted by brake pads. However, today’s elite teams in open wheel, Indy and Trans Am racing are moving away from crack prone, cross-drilled brake rotors in favor of rotors modified with a fatigue resistant slotting process.

Power Slot’s ProStop II rotors were developed to combine the look of a cross-drilled rotor with the durability of a slotted rotor. ProStop II rotors are enhanced with a series of four drilled “dimples” that look like cross-drilled holes (especially when brake dust is collected at the bottom of the dimples after several hundred miles of driving). By installing ProStop II rotors, a driver can have the “look” of a cross-drilled rotor and the performance of a slotted rotor without compromising the structural integrity of the rotor. ProStop II rotors with their faux-drilled dimple treatment are specifically designed to provide a safer alternative to drilling crack prone holes through cast iron rotors and offer a more aggressive appearance than the original ProStop rotors.

Power Slot's slotting process and faux-drilled treatment removes less heat absorbing mass and less of the rotor’s surface area than conventional cross drilling to help maintain the highest possible co-efficient of friction for the brake pads to work against."


If the rotors you've purchased are truly cross-drilled, as well as being slotted, then I suppose the question is "will they hold up just fine under normal street use?". My guess is yes. How would they fare under very demanding street and back road use? Probably not very well, from what we've read.

So they may be perfectly fine for you, and perhaps many others here as well - they look great, they're treated against rust, and appear, from reading, to have good metal in them.

If I, however, because of my need for speed, were to quickly grab a set of rotors just from the offerings you've presented I'd choose the Power Slot ProStop II's - for the reasons clearly laid out in the above quote.

Just my thoughts. Please keep on posting.

 

[Goose]

DZeckhausen, Could you tell us your recomendations on a good set of rotors?

Thank you.

The ATE Powerdisc rotors with the "mutipurpose groove", for those who haven't seen them, use a unique slot pattern that resembles an atom with orbiting electrons. These are often referred to as the "nuclear rotors."

The steep angle of the grooves and the fact that they make these only for rotors that are non-directional (meaning the internal vanes point straight out from the center of the rotor and there is no "left" or "right") ensures that the rotors are not weakened by a slot running in the same direction as an internal vane.

The Powerdisc pattern is an attempt to break out of a commodity market with something that is recognizable, not only by the packaging, but also once mounted to the car. Brake dyno tests show no significant advantage in bite over traditional slotting patterns, so the "atomic" pattern is nothing more than a marketing gimmick.

Since ATE doesn't use a Dacromet coating like the OEM factory rotors, these tend to rust in the grooves, in the internal vanes, in the center hub, and any other unswept area, often causing an orange "ring of shame" that is visible with open wheel designs. Not the sort of thing you want on a show car.

 

[DZeckhausen]

I just don't believe having holes and slots is a bad thing. If it was a bad idea then why do so many places offer them?

Because people are gullible and will buy them.

Do a quick Google search on the "Tornado Fuel Saver" and see how many places offer this piece of junk. Here's a product that is nothing but a scam and Consumer Reports recently documented that it reduces the gas mileage on your car. Yet even Amazon.com sells them!

You can't assume, because lots of places sell a product, that the product is any good. The only thing you can conclude is that the product is profitable to sell.

 

[DZeckhausen]

DZeckhausen, Could you tell us your recomendations on a good set of rotors?

I'm not aware of any good aftermarket rotors for the 300C yet. At this point, if my stock rotors were worn out, I would buy a new set of factory rotors from a discount Mopar dealer.

I wouldn't be surprised if Brembo and/or Powerslot have replacement rotors for the 300C in the development pipeline.

 

[marlinspike]

If it was a bad idea then why do so many places offer them?

Um.....you're...you're kidding right?