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Old 04-02-2001, 01:09 PM   #1
ESPO99RS
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I'm 555SOOB's brother and we put the rotors on before the meet saturday and they work great. I had all 4 of mine done. My brother had his front done. His friend who does the cross drilling has been doing this for years. I was going to go with slotted for street but he recommened the cross-drilled for street use. So, going on his experience I think they are a safe bet for most people. And like my brother said he has been doing this for VW and BMW clubs! But, if you want slotted rotors I believe he can do that too! So, he can slot or drill any rotors you may have even OEM if you want. We just want to know who in the area would be interested? Will keep you posted.
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Old 04-02-2001, 03:20 PM   #2
Pilot
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I don't want to rain on your parade (but I am going to anyway).

Cross drilled rotors are not something that anyone needs or wants for anything except pimp factor.

The only mechanical benefit to cross drilled rotors that can not be had any other way is reduced unsprung mass.

This benefit is severly reduced when you consider the following:

1) Cross drilled rotors do not have as much mass, and therefore less heat sink capability compared to regular or slotted rotors, they are therefore prone to warp or crack much sooner. The holes create a weak area in the rotor especially when drilled. Even factory Porsche rotors which are cast with the holes are failure porne under track use.

2) They DO NOT run cooler and they are less tempurature stable compared to slotted or regular rotors. Tempurature stability is key in rotor design. Heat cycles kill brake rotors just the same as they do racing tires. The more temperature stable the rotor is the less heat cycling will affect it, the longer it will last.

3) High quality modern brake pads do not "outgas" therefore slotting and cross drilling lose one of there main perceived benefits, which is to let the gas escape so the pads and rotors don't "surf". If you are using OEM pads or cheap aftermarket pads, then slotting may be in order for "outgassing" problems.

4) Slotted or crossdrilled rotors are better in the rain, but with all the downsides of drilled rotors why not just go slotted, nothing crazy, 3 slots is all you need, 5 max, 6 if your rotor is 13" or greater diamteter.

In conclusion cross drilled brake rotors are a bad idea for several reasons, and on a street driven car are pure waste of money and rotor longevity. Slotting has its advantages but tends to eat the pads a little faster than normal. For street use a standard rotor is all you need.

BTW just because this guy drills rotors for the VW and BMW clubs doesn't mean it is a good idea.
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Old 04-02-2001, 04:56 PM   #3
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To echo what Pilot was saying, Cross Drilling is an older technology that has very little use in today's world. No offense to your friend or anything, I'm sure he does a really good job and I know all of us here appreciate the offer. Slotting helps to clean the pads a bit, which does accelerate wear, however I'd be interested in seeing pricing on a few slots.

Thanks,
Fitz
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Old 04-03-2001, 12:45 AM   #4
555SOOB
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Post Cross-drilled Rotors

For those that are interested in increased braking performance. I have an arrangement with a friend of mine who can cross drill rotors. He has been doing this for several years now for some BMW and VW clubs. Race and street applications aval.

Take a look at the photo of mine on the modification pics. They are the typical long swirl for street use. Those of you that have the WRX we can crossdrill those rotors as well. I will be posting some more info and pictures of patterns later.
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Old 04-03-2001, 12:52 AM   #5
ttoversteer
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It was my understanding that crossdrilling rotors was dangerous: IE- cross-drilled rotors are more prone to cracking? I have seen many factory Porsche rotors develop cracks radiating from the cross-drilled holes.

And don't forget: Cross-drilling reduces surface area. The less surface area there is for the pads to contact, the less friction is available for braking.

If I'm wrong, please correct me.
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Old 04-03-2001, 12:52 AM   #6
tmat3
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Based on my experiences, cross-drilled rotors tend to warp faster than stock rotors. My Civic's x-drilled rotors warped in less than 7000 miles! How well do your rotors perform on cars mainly driven on city and highway roads and some autox (i.e. my car)? I'm just curious. Thanks.
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Old 04-03-2001, 05:48 AM   #7
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OK, Guy's I wasn't looking to start a debate here. Yes it's true that it's mainly a cosmetic upgrade. However it will help with brake fade at high speeds. ( I've heard the great crack and warp speech before and the results have always been 50/50 a lot of that is dependant on the driver and there brake usage.) The reason I posted this information was to see what kind of interest there was for this. Slotting is another application that he can perform on these rotors as well. Only straight slots tangent to the rotor hub. The cost is $30per rotor. I'm offering this as cheaper alternative than having to go out and spend $200 or more on an equivalent product. This can be done on any kind of rotor factory or aftermarket. I appreciate all the tech knowledge that everyone has. If anyone IS interested let me know.
Thanks!
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Old 04-03-2001, 07:27 AM   #8
Pilot
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Cross drilling will not help with brake fade at high speeds. Quality brake pads, and quality brake rotors (good metal, like say a Brembo rotor) will take care of that. There is no 50/50 in cross drilling, it is always a bad idea, I don't care who is driving. Some driver's use less brake. But however you drive cross drilled rotors will still ot last as long as standard or slotted.

Now slotting for $30 is another matter. I assume when you say tangent to the rotor hub you mean diagonal to the radius.
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Old 04-03-2001, 08:21 AM   #9
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Well you are entitled to your own opinion! When you can support your statements with factual data then "maybe" I'll buy into it! Again as Stated this is a cheaper alternative for those who DON'T want to spend obscene amounts of money on pads and rotors.

Yes Tangent to the rotor hub means diagonal to the radius.
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Old 04-03-2001, 09:30 AM   #10
Fitz
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Here's your "factual data" taken from the Baer racing catalog. If you don't feel like reading the whole article, at least read the last section that says "So if you encounter claims that crossdrilled rotors will measurably increase performance, improve cooling, or last as long as non-drilled units, talk to someone else."


CROSS DRILLED ROTORS
"Q: I understand crossdrilled rotors offer substantial benefits in cooling, but they crack and fail almost immediately, how can both be true.

"A: Actually neither is true."
There are really only two reasons that rotors are crossdrilled; "1) To relieve the gasses emitted from the breakdown of the bonding agents used in the manufacture of some brake pads. This condition, known as "outgassing", can create a pneumatic barrier between pad and rotor which results in a normal pedal feel but very little friction to stop the vehicle. Ironically, current race pads from Performance Friction and several others are pre-burnished and do not have any outgassing problem;"
2) For COSMETIC reasons. The truth is today's ever larger and increasingly open wheel styles, the brake system has become
instrumental in creating a "look". Porsche and Ferrari, as an example, certainly know the need for crossdrilled rotors has passed,
yet they still deliver their top of the line cars with crossdrilled rotors. This is the same reason that Baer offers all systems with or without crossdrilled rotors.
"Crossdrilled rotors do offer about 15% less service (life) in most serious to extreme street use. In actual track use this reduction can be upwards of 50%. However, most SPEs (Self Proclaimed Engineers)
suffer from the mistaken conclusion that the small hairline fractures which migrate from gas relief holes indicate "a rotor which is
terminal and must be replaced". This too is untrue. these surface fractures are normal with any crossdrilled, slotted, or "dimpled"
rotor. the cracks which warrant rotor replacement are any which actually cause a pulsation in the pedal, or which are radial thru the edge of the rotor.

So if you encounter claims that crossdrilled rotors will measurably increase performance, improve cooling, or last as long as non-drilled units, talk to someone else."

Edit: Spelling

[This message has been edited by Fitz (edited April 03, 2001).]
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Old 04-03-2001, 09:39 AM   #11
96Lconversion
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geez people, get off the guys back, he is trying to do everyone a favor, if you don't want it done, then keep your mouth shut. I might be interested in the slotted rotors, what process s used to do this? And do you have pics of those climate control dials n white?? (were you the one who asked me about those when we were all leaving? I was in the green sedan) Thanks for your help.

Bill
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Old 04-03-2001, 09:53 AM   #12
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"However it will help with brake fade at high speeds. ( I've heard the great crack and warp speech before and the results have always been 50/50 a lot of that is dependant on the driver and there brake usage.) "

He made some claims that Pilot and I disagreed with.

"When you can support your statements with factual data then "maybe" I'll buy into it!"

He then asked for factual data to support our arguements. No one jumped on him for offering to crossdrill our rotors, we just brought up some related complications that may occur because of this process. Let it be known that I'm interested in have mine slotted, just not crossdrilled.

96Lconversion, maybe you should go back up to the beginning of the post and read the WHOLE thing, instead of just a tidbit here and there before posting something like that. I'm sure you'd see that Pilot and I weren't intending to be malicious in any way. We were just trying to inform others about crossdrilling and how the need for it has expired with the new materials they're currently using in break pads.

Best regards,
Fitz
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Old 04-03-2001, 09:53 AM   #13
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I commend you on your research! I agree with most of what I read.
Again I would like to state that this offer was put out as an alternative to spending large amounts of money on aftermarket products. If no one is interested then I will retract the offer. I will NOT continue to waste my time arguing about this topic anymore.
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Old 04-03-2001, 09:53 AM   #14
mav1c
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Pilot & Fitz,

GREAT explanation on why crossed drilled rotors are NOT a good idea. It still amazes me to see ANY cars with crossed rilled rotors nowadays. The ONLY reason Porsche, Ferrari, and other high end cars still have rotors CAST with the holes, is to reduce unsprung and rotating weight, on their HUGE 13-14" rotors. Look on ANY professional race car, and you will NOT see cross drilled rotors, just slotted.

I have slotted rotors and I realize that it's a bit overkill, but still functional. I also had them Cryo'd so that helps reduce warpage.

My $.02
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Old 04-03-2001, 10:05 AM   #15
ttoversteer
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FYI: I have SLOTTED Brembo rotors... They are great at evacuating water, but they do eat the pads faster than "normal."
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Old 04-03-2001, 10:10 AM   #16
Pilot
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Thanks Fitz! You beat me too it. I was going to cite the same article.

Bill, I'm not trying to get on his back, I'm simply posting factual information that 555SOOB seems to be unaware of. I don't want NESIC members going out and getting their rotors crossdrilled without knowing all the facts. Slotted rotors OTOH can be beneficial even though IMO overkill for street use.
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Old 04-03-2001, 10:19 AM   #17
ESPO99RS
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Exclamation

Pilot & Fitz,
My brother was just bringing this up to see if anyone was interested in it! Everyone is entitled to their own opion, but:
"I don't want to rain on your parade (but I am going to anyway)"
I thought this was something we tend to avoid in our club? I think everyone in the club is smart enough to make their own decisions if they would want cross-drilled or slotted rotors. And if they have questions they can search the hundreds of other threads this topic has been brought up on. If you 2 aren't intersted then please don't post. Again we were just trying to help club members save some money on something they might want, that's all!
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Old 04-03-2001, 10:36 AM   #18
redobs
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Man, I don't check the board for the morning and see what happens.

OK, 555soob, I think it is great that you are tryin out fellow members. And I'm sure everybody agrees with me there. As you can see some people would like to get their rotors slotted, but not cross-drilled.

The argument here is why not to get cross-drilled. Yes, it is a cheap alternative, but did you ever think of how much it would cost when your rotor does crack from such an application. Probably, just as much as it would have cost to get new rotors in the first place.

As you can see, we like to watch each other's back and maybe prevent them from making a big mistake. I'm just trying to show you where Pilot and Fitz are coming from. It's not to put someone down and say I'm right and you're wrong, but to inform people.

That's what's so great about this club, we a resource of information, and we take care of one another. Try finding that in any other club.

-Pete

BTW, Pilot owns at least two Porsches, races on a regular basis, plus he works at a shop that works on race car prepping. So, if I were to take anybody's opinion, it would be his. I thought I'd let you know his background.

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Old 04-03-2001, 10:37 AM   #19
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I appreciate all of the info that has been displayed. I also think that it is good that you are interested in keeping people from making any mistakes. All I want to do is offer the service to anyone that maybe interested. As I mentioned he has the capability to do cross drilled or SLOTTED.
I believe that this should be left to the discretion of the buyer. I am not trying to mislead anyone into thinking that cross drilling is the way to go. All I want to do is save people some money. I would like to close this posting now. Please contact me only if you are interested in the service.
Thanks
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Old 04-04-2001, 07:58 PM   #20
Chuck Annicelli
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Hey guys thanks for both sides of the story. I have seen posts on this befor. I think it is good when people give their opinions on things. Not everyone has a chance or time to search old topics. Thanks to you guys for the offer and thanks for the info.

Chuck
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Old 04-05-2001, 07:34 AM   #21
Jon [in CT]
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As Pilot pointed out, above, the holes in Porsche rotors are not produced by drilling; they are formed during the casting process. Porsche does it this way in order to preserve the metal's micro-structural integrity.

Porsche's latest braking system, called the Porsche Ceramic Composite Brake (PCCB), also uses holes in the rotors, instead of slots. The rationale for the holes, according to the 12/00-01/01 issue of Christophorus magazine published by Porsche, is "to facilitate cooling and provide good wet-response behavior." I presume Porsche engineers are aware of the existence of slotted rotors, yet they still choose holes.

Why?

Perhaps they don't understand braking technology? This seems unlikely given that, since 1960, Porsche has been awarded more than 300 individual patents for braking-system developments and innovations.

Perhaps they suffer from not-invented-here syndrome? I guess that's possible, but far-fetched.

Perhaps they've tested both and concluded holes are superior to slots in rotors? This one gets my vote.
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Old 04-05-2001, 08:49 AM   #22
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Jon: As was said above, it's for unsprung weight purposes. Plus CAST cross drilled rotors are slightly stronger than actually drilled rotors.


ESPO:
"""""I think everyone in the club is smart enough to make their own decisions if they would want cross-drilled or slotted rotors.""""


I disagree. I did not know that slotted rotors were that much better than cross drilled until I saw the info poster here. So yes, thanx to the wonderful people on this board, I am NOW smart enough to make the correct choice.




[This message has been edited by y2k4door (edited April 05, 2001).]
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Old 04-05-2001, 01:02 PM   #23
ttoversteer
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BTW and FYI:

I got this info from the Baer website:
http://www.baer.com/

Quote:
Q: I don’t want to spend the money for a complete brake upgrade. Do you offer cross drilled rotors to work with my factory brakes?

Yes. Although there are some companies
which sell cross-drilled rotors as an actual
performance upgrade, in our extensive testing
we have seen no improvement to be had by
simply crossdrilling stock rotors. This is why
Baer has developed EradiSpeed™ rotor
upgrades for a variety of applications. Although
it is true the crossdrilling, the slotting, or for
that matter the zinc surface washing, are
cosmetic enhancements, EradiSpeed™ rotor
packages also feature rotors with thicker
cheeks to provide more heat sink capacity in
the fire path of the rotor. Also, they all feature
directional vanes for greater pumping efficiency,
as well as a two-piece design where the hat, or
hub/hat section of the rotor is CNC machined
from a solid billet of aluminum and is then fixed
to the rotor ring using National Aviation
Standard (NAS) stainless hardware. In other
words, the EradiSpeed™ is much more than
just the most visually appealing direct
replacement rotor, it is the only upgrade of its
type which can actually deliver the benefits of
greater heat absorption, increased durability
and lighter total weight.

In racing, crossdrilling was designed to alleviate
a problem known as out-gassing. In some of
the older pad compounds, when the pads
reached elevated temperatures consistent with
performance or racing use, the binder (that’s
the material that holds the friction material in
place) boiled off, producing a gas. This gas
would build up between the rotor and the brake
pad, effectively keeping the pad from directly
contacting the rotor. The holes provide a relief
path for these gasses, as do slots, so the pad
can once again contact the rotor. Crossdrilling
was NOT designed to facilitate cooling.

Although Baer offers crossdrilling as an option
on their systems, it is offered as a cosmetic
option only. However, with an EradiSpeed™
rotor upgrade, unlike a cosmetically altered
stock replacement rotor, you will benefit from
improved durability, greater heat sink capacity,
lighter total weight and the visual excitement of
a 2-piece, aluminum centered, crossdrilled,
slotted and zinc washed appearance.
Take it for what it's worth.

-T
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Old 04-05-2001, 01:33 PM   #24
Pilot
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Actually on the PCCB (as I understand it) the silicone/carbon fiber rotors don't take well to slotting, ergo the holes for water evacuation.

Ever look really closely at a Porsche 911GT1 in race trim? Slotted rotors when required to use iron instead of Carbon Fiber. Porsche does often suffer from "not invented here" syndrome. Why do you think they continue to eschew dog ring gearboxes in favor of syncronized gearboxes even though the dog ring boxes offer improvements in lap times due to quicker shifting.

Also holes will wear down the pad less agressively than slots, yet another street compromise ofr the Porsche rotor over slots.

Now think about how large a crossdrilled Porsche brake rotors is. The smallest one is almost 12" in diameter and 1.25" thick. This rotor contains a lot more mass than a Subaru rotor.

Therefore you do not want to drill a Subaru rotor because it simply does not have enough mass to handle it.

This thread is not about crossdrilled Porsche rotors which are prone to failure under racetrack conditions anyway, but about cross drilling an OE size Subaru rotor.

Also keep in mind that I don't reccomend slotting OR drilling for street use.
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Old 04-05-2001, 01:37 PM   #25
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