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**SVOPaul** · 06-03-2002, 08:09 PM

This is NOT normal with cross drilled rotors....only the poorer quality ones. I have never had a set of Porterfield rotors but every Powerslot/Powerstop rotor I have ever seen has had cracks in them with normal street driving and they are poor castings. The experience I have had with Stillen over 3 years now has not shown a single rotor with cracks....You also have to consider the pad compound you are using, a harsh pad could cause cracking from excessive heat. You might consider a slotted rotor for extreme track use but I would also suspect your pads as being way too aggressive.

**vrinner** · 06-03-2002, 08:36 PM

Cross drilled vs. not

I saw a post from another site that said that cross drilled rotors are bad for just about any application. Same for slotted. Although they might help cooling/venting gas, the slotting and drilling will ALWAYS cause a weak spot in the metal and COULD crack under heavy use (like the road racing I do).

I bought the rotors and pads at the same time from Porterfield. The pads are the R4 race compound so I would imagine they are the most aggressive compound they make. You would think that if they were not compatible, they wouldn't sell them together. As far as quality goes, I have heard nothing but good things about Porterfield pads and rotors. Any other suggestions?

Thanks!

**SVOPaul** · 06-04-2002, 08:16 AM

Whoever posted that info is uninformed....there is probably more misinformation floating around out there about brakes than anything else pertaining to cars....I have even seen articles published in magazines that were full of misinformation. There is a right way and a wrong way to manufacture drilled and slotted rotors...you don't just go and drill holes into a rotor, there is a procedure to maintain the structural ingtegrity. You can take this information however you choose but I use and race on these rotors as do many of my customers and neither I nor my customers have experienced these problems.

Another cause could be your driving style...I don't know how you drive or take care of your brakes but if you come down to a stop from high speeds and just keep your foot planted on the pedal, you are going to keep the rotor from cooling off equally and cause warpage and possible heat cracking. There are a few different variables....

**svono50** · 06-04-2002, 01:59 PM

I don't have any direct experience in this particular subject, just what I have read in the past. If you want to get some solid advice on what type of pad compound/rotor combo to run on a track car (auto-x or OT), I would suggest checking out the Road Racing & Auto-X Mustang (RRAX-Mustang) list on Yahoo Groups. The guys on that forum have a good pool of experience and are willing to share their knowledge and opinions. I know Gene Beaird, who has posted on this forum, spends time on that list and can vouch for their knowledge also. Good luck with tracking down the right combo for your car.

**vrinner** · 06-04-2002, 02:21 PM

Cross drilled rotor question

So here is a link that someone sent me to on another forum. Check it out and tell me what you think.

Altimas.net - Crossdrilled/slotted rotors-why they are like this, like that-final discussion

http://corner-carvers.com/altimathread.php.html

**SVOPaul** · 06-04-2002, 09:05 PM

His theories are incorrect in regards to "dissipation of brake dust" and the uses for slotted and cross drilled....aside from that this guy bought a set of good rotors in blank form(I suspect because he was too cheap to buy the already drilled or slotted rotors from Brembo) and took them to a local machine shop or garage to get them drilled and slotted?!?

Commenting on this guys post from another forum is a waste of time, he has proven his "qualifications" with his statements.

**bigwingsaleen** · 06-05-2002, 11:00 AM

drilled / slotted rotors

I have the Stillen cross drilled rotors on the '84 Turbo Gt and have not seen any signs of cracking at the holes....also using Stillen Metal Matrix pads. This combo is a HUGE step up from the factory pieces.

**vrinner** · 06-05-2002, 03:06 PM

Cross drilled rotors

Originally posted by SVOPaul
His theories are incorrect in regards to "dissipation of brake dust" and the uses for slotted and cross drilled....aside from that this guy bought a set of good rotors in blank form(I suspect because he was too cheap to buy the already drilled or slotted rotors from Brembo) and took them to a local machine shop or garage to get them drilled and slotted?!? Commenting on this guys post from another forum is a waste of time, he has proven his "qualifications" with his statements.

OK...let me try and qualify myself first...I have been auto crossing for about a year and a half. I have been time trialing for about 6 months. That is the extent of my raceing experiance.

Now...This is the first set of front rotors that I have had to get for my race car. My stock rotors actually cracked completly through. My rear rotors are Porterfield so I decided to get the fronts from them also. I assumed that cross drilled rotors were better than non cross drilled for racing (maybe it was because they look so damn cool) and my thought was that they would cool better and because the stock ones cracked, cross drilled would be better and would be less proned to cracking.

Having posted this question on several racing forums, the general consensus is that cross drilled rotors ARE more prone to cracking and should NOT be used on race cars unless they were formed that way when cast. Although several people have posted that they have not had a problem with cross drilled rotors on street cars, and many have posted that cross drilled rotors have caused them problems, I am leaning towards regular rotors.

I spoke with Porterfield and they even said that cross drilling rotors will tend to crack and that with todays pads, the need for venting of gasses is not really an issue anymore. Now the one thing that they did say is that as long as the cracks do not run to the outer edge of the rotor or do not go between holes, they should be fine.

**richsvo** · 06-05-2002, 03:35 PM

vrinner,

I think that maybe you should, at least, consider that maybe one manufacturer may do things differently than others? Som may know what they are doing, they research it, test it, etc. and others may not. No offense, but I have never EVER heard of Porterfield brakes...Brembo, Stillen, Stainless Steel Brake Corp., etc, yes, but not Porterfield. I would think that if they were that good, then maybe more people would have them. Everyone that I know that has Brembo, or Stillen tell me the same thing....They don't crack, because they are matched to the pads and designed for racing, etc. For example, I know that Stillen makes their pads from materials, none of which are harder than the rotor surface, therefore making it almost impossible for them to crack...if you think about it, that kinda makes alot of sense. Most people that I know with cracked rotors were running a very aggressive, and HARD pad...well.....duh!

Just my .02 e-cents...

Rich

**vrinner** · 06-05-2002, 03:44 PM

Cross drilled rotors

Porterfield is a local (Southern California) company that mainly manufactures racing brake pads and rotors. Check out www.porterfield-brakes.com

They came recomended to me by other local racers. Stillin and Brembo I'm sure are fine, I just thought that I would give the "local guys" some support. Again...being a road racing newbie, I'm trying to figure all of this stuff out. I really appreciate all the advice that everyone gives and am learning from all of it.

**svobud** · 06-05-2002, 06:20 PM

I've got Stillen Rotors/pads. Cross drilled. They've been on the car for 2 1/2 years now - something like 15k miles. They've seen semi daily use, long distance trips, 3 open road course events, and 3 autoxing events. NO cracks. Car is stock weight. I thought about using the Slotted Rotors (which are suppose to be better suited for Open Track) over the Cross Drilled - but figured I would be doing more Autoxing than Open Track. The cross drilled offer a 'quicker bite' - which is what I was looking for....cause I don't see too many 'braking from over 100mph to 40mph' situations.

**SVOPaul** · 06-05-2002, 07:05 PM

Re: Cross drilled rotors

Originally posted by vrinner

1)Now...This is the first set of front rotors that I have had to get for my race car. My stock rotors actually cracked completly through. My rear rotors are Porterfield so I decided to get the fronts from them also. I assumed that cross drilled rotors were better than non cross drilled for racing (maybe it was because they look so damn cool) and my thought was that they would cool better and because the stock ones cracked, cross drilled would be better and would be less proned to cracking.

2)Having posted this question on several racing forums, the general consensus is that cross drilled rotors ARE more prone to cracking and should NOT be used on race cars unless they were formed that way when cast. Although several people have posted that they have not had a problem with cross drilled rotors on street cars, and many have posted that cross drilled rotors have caused them problems, I am leaning towards regular rotors.

3)I spoke with Porterfield and they even said that cross drilling rotors will tend to crack and that with todays pads, the need for venting of gasses is not really an issue anymore. Now the one thing that they did say is that as long as the cracks do not run to the outer edge of the rotor or do not go between holes, they should be fine.

1) your thinking was on the right path....question...are the holes in your porterfield rotors straight cut or chamfered? I would put money on the cause of your cracked rotors is a direct result of a pad that was way too aggressive....the brake pad should not wear the rotor surface and many of them have materials in them harder than the rotor surface itself....not good.

2)I would also be willing to bet that your "general consensus" from the other forums are either A) people repeating what they heard from someone else who knew a guy who knew a guy etc, etc....who have NEVER even owned a set of cross drilled rotors or B) people who bought cheap rotors, poorly prepped rotors or rotors they or the local machine shop drilled through. Poor quality cross drilled rotors CAN cause a problem but MOST of the time it is a poor choice of a pad compound....a pad that is too aggressive will damage the rotor. Most people don't take the time to understand braking Dynamics and just repeat what they hear....this is how the whole "cross drilled rotors crack" wives tell is carried forward. Your choice of pad compound is just as important if not more so than your choice of rotor.

3) Flat out incorrect! The guys at porterfield(or whoever told you that) is obviously a salesman without a clue....Grass Roots Motorsports did an article once that said the same thing about modern pads and no need for outgassing which was totally incorrect....I questioned the editor about it and they published the article from an individual without checking the validity of it...they apologized to me for the misinformation. Modern brake pads DO need to vent the gasses produced and a cross drilled rotor that is properly prepared is NOT "prone" to cracking. Obviously porterfield has this problem a lot if he is making excuses for it. And to say "the cracks should be fine as long as they don't go to the outer edge" is taking on quite a liability.....

I have customers that do all sorts of things with their brakes...from street driving to open track with braking from 130MPH plus and I have NEVER had a complaint or concern with cracking. This is why I use and offer the brakes I do...because they are a quality product without issues. It concerns me that there are manufacturers/suppliers out there that are willing to make excuses and put someones safety at risk selling an inferior product.

Any rotor "can" crack or warp....again it's a combination of the quality of the basic product, the detail and care taken in preparing it and finally the choice of brake pad....harder, carbon metallic or steel brick isn't always better.

**vrinner** · 06-05-2002, 08:04 PM

Re: Re: Cross drilled rotors

Originally posted by SVOPaul

1) your thinking was on the right path....question...are the holes in your porterfield rotors straight cut or chamfered? I would put money on the cause of your cracked rotors is a direct result of a pad that was way too aggressive....the brake pad should not wear the rotor surface and many of them have materials in them harder than the rotor surface itself....not good.

2)I would also be willing to bet that your "general consensus" from the other forums are either A) people repeating what they heard from someone else who knew a guy who knew a guy etc, etc....who have NEVER even owned a set of cross drilled rotors or B) people who bought cheap rotors, poorly prepped rotors or rotors they or the local machine shop drilled through. Poor quality cross drilled rotors CAN cause a problem but MOST of the time it is a poor choice of a pad compound....a pad that is too aggressive will damage the rotor. Most people don't take the time to understand braking Dynamics and just repeat what they hear....this is how the whole "cross drilled rotors crack" wives tell is carried forward. Your choice of pad compound is just as important if not more so than your choice of rotor.

3) Flat out incorrect! The guys at porterfield(or whoever told you that) is obviously a salesman without a clue....Grass Roots Motorsports did an article once that said the same thing about modern pads and no need for outgassing which was totally incorrect....I questioned the editor about it and they published the article from an individual without checking the validity of it...they apologized to me for the misinformation. Modern brake pads DO need to vent the gasses produced and a cross drilled rotor that is properly prepared is NOT "prone" to cracking. Obviously porterfield has this problem a lot if he is making excuses for it. And to say "the cracks should be fine as long as they don't go to the outer edge" is taking on quite a liability.....

I have customers that do all sorts of things with their brakes...from street driving to open track with braking from 130MPH plus and I have NEVER had a complaint or concern with cracking. This is why I use and offer the brakes I do...because they are a quality product without issues. It concerns me that there are manufacturers/suppliers out there that are willing to make excuses and put someones safety at risk selling an inferior product.

Any rotor "can" crack or warp....again it's a combination of the quality of the basic product, the detail and care taken in preparing it and finally the choice of brake pad....harder, carbon metallic or steel brick isn't always better.

1) They are chamfered. According to Porterfield, their race compound pads are "rotor friendly".

2) I guess then that you could make a big argument with I'd say about 90% of the people who post on these groups. Not that 90% of the people are experts or are road racing experts but at least they "sound" like they know what they are talking about...hey...so do you

3) At this point I dont know who to believe. The salesman at Porterfield or the salesman at SVP (you

).

Like I said, I am by no means and expert in any of this brake stuff. I can only go by what people whom I think are informed tell me. I do think that you are informed...I also think that Porterfield is informed. Now you both tell me two different things. Cracked rotors do not sit well with me and I don't think that I will be running them.

So how much do cross drilled Stillen or Brembo rotors and pads go for on an SVO? And will you stand behind your product if they crack after just a few sessions?

Boy do these brake discussions get long. Everyone has an opinion.

**SVOPaul** · 06-05-2002, 09:36 PM

Although I like to sell parts etc since it is what I do, I am not here to sell you my parts directly. I just want to see misinformation and wives tales dispelled....there is an awful lot of misinformation out there and I come across it on a daily basis. My philosophy in regards to what I sell is that I use everything I sell on my own vehicles....I don't like surprises and I want the parts you get to do exactly what I say they do(also why I personally use them).

We didn't touch on your driving style, are you concious about letting your brakes cool? not that it had anything to do with cracking of your rotors but it can. This is also one area that is the reason no performance parts carry a warranty...however that doesn't mean you are left out in the cold either....I do stand behind my products...but again, I am not here to sell you anything...just to help with information.

Are you running any brake cooling ducts? another area to consider if you are not.

I'll call my contacts at Stillen since they are also in Southern, CA and ask them about Porterfield(since I have never heard about them), they always give me an honest take on other products....

If you would like to try the rotors or pads that I have, feel free to call me....my advice is free and you are not obligated to anything...I am here to help. I can tell you that Bud is probably the best driver I know on a road course and he drives hard...his brakes are performing flawlessly...there are also a lot of others here running them without issue.

Give me a call at 205-629-3126 and well go over options, issues and what you should expect out of brakes and pads. I agree with you though...cracked rotors are not an option, brakes are the most important aspect of your car.