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    1. #1
      Join Date
      Dec 2002
      Location
      Lost Wages, Nevada
      Posts
      2,674
      Country Flag: United States

      If crossdriled and slotted rotors are so bad then why, Page one (from old site)

      yody
      Registered User
      Posts: 203
      (6/8/04 2:24 pm)
      Reply
      If crossdriled and slotted rotors are so bad then why....
      --------------------------------------------------------------------------------
      if cross drilled and slotted rotors are so bad except for porsche then why do stock mercedes S500's and 600's all have crossdrilled rotors? also i took a look at the havoline nascar and it had slotted rotors on all four coners. i have also seen them on other stock production cars? i am not saying that they are good, but if a nascar car uses them and mercedes and porsche, their must be something good about them? also people were saying that they were okay on porshches because they were cast in but wasn't the argument was if they worked or not? not if they lasted? so if they don't do anything for perfomance then why do all these high end cars use them including a nascar?
      firebird website

      ddennis68
      Registered User
      Posts: 169
      (6/8/04 2:52 pm)
      Reply drilled rotors
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      I'm pretty sure Mercedes is doing it for marketing, at 50K a car for a cheap one they can afford to warranty a few for 3/36 to sell cars. Slotted rotors do not have the same negative side affects drilled rotors do, just hard to find cast slotted rotors that haven't been drilled too and that fit your application. Alot of cars run things they shouldn't, Chrysler for example puts a 350 ft lbs engine in front of a trans that has trouble behind a 200 ft lbs V6. Go figure, just because a manufacter does something doesn't by any means mean it is a good thing to do. Ask any tech how many times in a day they cuss enginering up and down, I personally think they are idiots.

      andrewb70
      Registered User
      Posts: 2481
      (6/8/04 5:43 pm)
      Reply
      Re: drilled rotors
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      The Mercedes probably uses Brembo rotors that have the holes cast in. Those are not as prone to cracking as drilled rotors.

      Andrew
      Project GatTagO



      yody
      Registered User
      Posts: 204
      (6/8/04 6:15 pm)
      Reply
      Re: drilled rotors
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      i find it hard to compare chrysler engineering to mercedes/porsche i doubt mercedes does it for looks because you can barely see them behind most stock wheels. also i was saying that if they put them there they must be because they help braking, wasn't that one of the arguments was that they do not improve braking?
      firebird website

      ddennis68
      Registered User
      Posts: 170
      (6/8/04 7:14 pm)
      Reply Re: drilled rotors
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      You don't compare Mercedes to Chrysler huh?? Who do you think designed the transmission in the new HEMI 300C and Magnum. Wait and what about the Crossfire, who do you think designed the whole darn car? Chrysler and Mercedes are a whole lot closer on the design table than you think-give it another year, it looks like all Chrysler cars will be running Mercedes transmissions and the Buss network is crossing over too.

      andyf
      Posts: 17
      (6/8/04 9:35 pm)
      Reply rotor design
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      It is a tough question to answer without actual data and the people who have the data don't seem too prone to share it. To really answer a question like that you need to be very specific with what your test conditions are.

      Do you want a rotor to provide ultimate brake force for 500 miles of racing on a dry track (NASCAR) or something that works good for 30K miles in the wet and dry (OEM production), or something that works good on the street and still works pretty well on track days also (Porsche OEM stuff).

      Engineering is all about making the best compromises. Sometimes marketing leans over the wall and says "screw the data, our customers want holes and slots". So sometimes that is what goes out the door.

      I actually don't know the answer to the question but I like the Porsche rotors and I have confidence in the Porsche engineering methodology so I'm more than happy to hang Porsche stuff on my car. There is a lot of junk aftermarket brake stuff that I wouldn't consider putting on my car though so buyer beware.

      RokketRide
      Registered User
      Posts: 5
      (6/16/04 4:18 pm)
      Reply slotted
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      I put slotted rotors on the import I was driving when I worked at Brembo.

      There was a welcome improvement in the overall feel and consistency of the brake pedal.

      walapus
      Registered User
      Posts: 203
      (6/17/04 9:33 am)
      Reply idiots?
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      "Ask any tech how many times in a day they cuss enginering up and down, I personally think they are idiots."

      First of all, you misspelled engineering.
      Secondly, and somewhat unfortunately, it is the engineer's job to please the customer, not the tech. This sometimes means compromises that result in a bolt being in hard-to-reach spot, or whatever. It's not stupidity, it's a choice. If we made everything super-simple to disassemble, engine bays would be gigantic, weight distribution would be horrendous, and suspension geometry would be horrible. EVERY engineering decision involves some sort of compromise.

      Admittedly, there are some engineers that make me wonder sometimes, though!
      However, there are also some mechanics that make me do the same thing!

      The best engineers are the ones who talk with and bounce ideas off the guys on the floor, because of their different perspective and invaluable experience. The best techs are the ones who talk to the engineers, so that they know how much thought went into every decision, and why things ended up the way they are.

      The worst of both fields are the ones that develop a superiority complex.

      davidpozzi
      Moderator
      Posts: 1189
      (6/24/04 1:07 pm)
      Reply
      Re: idiots?
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      My apologies to yody for getting off track but I have a chance to gripe!

      Every auto engineer should first be required to work as a Tech for a fiew years.
      I've got a farm pickup that we change the inside door handles on at least once a year. Someone designed them to be made of pot metal and three quarters of the metal where the most stress is has been left off! BUT they have huge handles to grab with your whole hand, so you get lots of leverage over them and SNAP!

      The last pair I installed, I epoxied some steel welding rod on them to reinforce them, plus cut away half the handle so the guys can only grab the handle with two fingers!

      The 88 GM pickups had no grease fittings on the balljoints, and no alignment adjuster cams on the upper A arms. For the first alignment we had to pay the shop extra to install the adjusters so they could align it. The balljoints failed around 50K to 80K due to lack of lubrication.
      My buddy had his lower balljoint separate in his driveway.

      Two of our new flatbed IH diesel trucks came with plastic bushings on the front kingpins! They both failed by 50K miles and the replacement IH bushings were all plastic too! We installed aftermarket bronze bushings and they last.

      We have had countless failures of switches due to dust. The switches since 88 or so don't have sliding contacts, they have contacts that pinch together and they removed all the metal they can. One speck of dust on the contacts prevents power from flowing, they are not self cleaning and they are not sealed so dust can't get in.

      GM tail lights.
      The light bulbs plug in and there is so little metal in the sockets that the metal bends just a little and contact is lost. My cousin had a dog that slept in his truck while he worked, the dumb dog would lay on the brake pedal and the tail lights would be on for a half hour. The tail light sockets melted!
      David

      67 RS Camaro, 69 Camaro vint racer, 65 Lola T-70 Can-Am vint racer.
      ourworld.compuserve.com/homepages/David_Pozzi/

      Edited by: davidpozzi at: 6/24/04 1:11 pm

      yody
      Registered User
      Posts: 232
      (6/24/04 9:47 pm)
      Reply
      Re: idiots?
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      damn dogs!
      firebird website

      davidpozzi
      Moderator
      Posts: 1194
      (6/25/04 12:03 pm)
      Reply
      Re: More
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      I've got lots more but I'm holding back!
      67 RS Camaro, 69 Camaro vint racer, 65 Lola T-70 Can-Am vint racer.
      ourworld.compuserve.com/homepages/David_Pozzi/

      Ralph L
      Moderator
      Posts: 3554
      (6/25/04 8:38 pm)
      Reply
      Drilled rotors
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      I agree that drilled rotors are not for racing use, and that regular rotors are better, or atleast cast holes but it seems every production performance car i look at these days has drilled rotors, all porsches, some benz's, the C6, the new viper, even the Enzo ferrari, which is supposed to be a bad ass race car. Is this all just a marketing effort to sell cars? Why are these manufacturers "selling out"? I can see the ones on the Carerra Gt and Enzo becuase they're ceramic and the holes are cast and the rotors cost more then I even want to comprehend, but what's with Chevy and dodge doing this now too?
      Ralph
      Project Fantom Expected Completion - May 2005
      My Tahoe - "Black Mamba"
      Rendering of Project Fantom

      ddennis68
      Registered User
      Posts: 195
      (6/25/04 11:01 pm)
      Reply Re: Drilled rotors
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      Marketing-go check out corvetteforum.com those guys are always *****ing about warped rotors on the C5, they have tried everything-the only guys who have real success are the ones stepping up to 14" Wilwood stuff-at 3K it better work.

      Viper has been out for 11 years now and has always been on the top of the food chain-I would really like to see the 100-0 numbers from the new 05 and the 03 models to see exactly how much they improved going to drilled rotors. Once the brakes have the abuility to lock the tires, any other braking upgrades are in vane.
      Dennis-

      check out progress of Bondobucket

      conekiller13
      Registered User
      Posts: 720
      (7/2/04 1:59 pm)
      Reply To drill or not to drill
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      Every Porsche or Ferrari (Excluding the Carrea GT and Enzo) that I have seen at the track has had small stress cracks in thier cross drilled Brembo rotors. Brembo reps have told Me that this is just surface flaws and not structural, I disagree. Bear racing has done extensive testing on cross drilling and slotting and has come to the conclusion that their is no performance advantage. They offer it as a cosmetic upgrade only. Look at the GTS class in the ALMS. No drills or slots, just lots of ducting to the brakes.

      yody
      Registered User
      Posts: 244
      (7/4/04 6:49 pm)
      Reply results?
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      why don't you believe brembo, and what kind of research did baer do?

      SSWANAB
      Registered User
      Posts: 58
      (7/4/04 8:18 pm)
      Reply DIAMLER CHRYSLER
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      How can you not compare Mercedes and Chrylser, they are one in the same now. That is why they are looking more and more alike. If you get down to it, how many truly different manufacturers can you come up with, 5 or 6?

      IMO, most guys buying drilled and slotted rotors probably bought more for the looks than the perfomance, anybody planning on using them on the track should either know better or soon find out.

      How well do you think those disc simulators work that many hotrods got?

      ddennis68
      Registered User
      Posts: 210
      (7/4/04 10:50 pm)
      Reply Re: results?
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      Because anytime a manufacter's rep tells you there is nothing "wrong" with their product that should immeadiatly raise a red flag and make you question it. No product is flawless and "normal cometic flaws" are not normal(well maybe for drilled rotors it is) nor just cosmetic.
      Dennis-

      check out progress of Bondobucket

      conekiller13
      Registered User
      Posts: 729
      (7/5/04 10:32 am)
      Reply Cracks
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      I don't belive him 'cause I have seen those so called cosmetic surface cracks become full structural cracks. I have yet to see one of Baer's rotors crack. The research Baer has done has been with temp sensors on a brake dyno. Basicly a device with a driven rotor mounted on it, a caliper and various heat sensors. They can test how the rotor dessipates heat, what the coeficient of friction is and how it cahnges as things heat and cool. They found no advantage with drilling and or slotting. They will tell as You buy their product those things are for appearance only.


      Dan

      BADVELLE
      Registered User
      Posts: 39
      (7/6/04 2:03 pm)
      Reply
      Re: results?
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      **Because anytime a manufacter's rep tells you there is nothing "wrong" with their product that should immeadiatly raise a red flag and make you question it.**

      This is most definitely not true, if it is, then you are talking to a true "salesman", not a maufacturers' rep (if we are being generic with that title). Honest business people will acknowledge when there is an issue with their product and then work to correct that issue, not mask it with a comment like "there is nothing wrong with my product". I hear this type of talk from time to time and it really gets under my skin, especially when there are a few people that give everyone else a bad name. Sorry for the rant, I will stop here! Later.
      Craig

      ddennis68
      Registered User
      Posts: 215
      (7/6/04 5:21 pm)
      Reply Re: results?
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      Let me put it this way-in my 12+ years in the field I have dealt with dozens of true reps(not sales) including a vendor in Canada that builds Chryslers dashs, EIS brake parts (on several occasions), Bendix brake parts, Chrysler engineering and the vendors they do business with(ALOT), along with several others. In EVERY case there have a dozen reasons why things are not working correctly, it's never been because of a design or material flaw.
      Dennis-

      check out progress of Bondobucket

      chicane67
      Registered User
      Posts: 123
      (7/6/04 6:56 pm)
      Reply | Edit Re: results?
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      Refer to this:

      The end all to be all, cross drilled and/or slotted thread link

    2. #2
      Join Date
      Dec 2002
      Location
      Lost Wages, Nevada
      Posts
      2,674
      Country Flag: United States

      Page two

      BADVELLE
      Registered User
      Posts: 41
      (7/7/04 7:02 am)
      Reply experiences!
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      Dennis -

      The comments yesterday just hit me the wrong way (because I fit in the rep category, but am big enough to admit fault with my product), I do understand where you are coming from and I would say that those "reps" that you have dealt with have heads to big to let them admit mistakes. I have dealt with numerous engineers (not saying all engineers are this way) that do not realize how components operate once they get into the field and out of the shop/lab. In other words, they have "tunnel vision". I don't know if it is because they don't want to admit flaws/mistakes (we all make them) or they just don't know how things work in the real world. However, my experiences have been all with OEM (Big 3, suppliers, so forth) and not at all with aftermarket companies within our hobby. People and engineers like Kyle Tucker do their engineering homework/design and real world test these components. Then they stick behind the product and would admit if any mistakes were made, no doubt!

      When you get to big corporate world, things really change and the focus is on profits more than customer retention/satisfaction.

      Just my long .02 cents worth of experience.


    3. #3
      Join Date
      Dec 2002
      Location
      Lost Wages, Nevada
      Posts
      2,674
      Country Flag: United States

      An extension of the same subject

      McBride68camaro
      Registered User
      Posts: 167
      (4/12/04 2:18 pm)
      Reply Using larger drilled and slotted rotors
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      I have a posi-trac 3:23 rearend that is going into the 68, and I am looking to add different rotors onto it. The wheels I am using are very open and I am needing something nice behind them. The rotors I have now are probably 10". Can I add a larger rotor, and if so what am I going to have to do? This is just a stock rearend with disc brakes. Any ideas would be great.

      I will be running baer track slot n drilled in the front or corvette c5 setup.

      Thanks, Andrew

      Edited by: McBride68camaro at: 4/12/04 8:13 pm

      chicane
      Unregistered User
      (4/12/04 8:16 pm)
      Reply .......
      --------------------------------------------------------------------------------
      Man am I glad this isnt corner-carvers.com........

      There was a peticular and infamous thread on and about the use of cross drilled rotors and why not to use them. There was 30 plus pages of engineering, personal racing, and competition experience data in the thread, enough to choke a friggin horse and make you run the other way from using them. Not all of what was said, is in this posting, as it went thru the entire community and started threads on other boards, but you will get the picture I am sure.

      Be forwarned, this isnt for the meak

      Cross drilled rotors are not the rotor of choice, in street and/or competition use. All they are good for is the typical 'bling, bling' factor. The biggest factor is saftey in a car that will be driven HARD. If its just a simple streeter and isnt used too hard, I guess it might be acceptable to use them.

      But to get to the answer you are really looking for, most upgrade or 'plus' type kits provide you with a bracket and hardware to physically mount a larger diameter rotor to your current set-up, while retaining the same caliper....up to a certain point. Some calipers will and can only be used with rotors up to a specific diameter.

      McBride68camaro
      Registered User
      Posts: 171
      (4/12/04 9:10 pm)
      Reply whoa, well that kinda gives me a better understanding.
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      Well I knew slotted and drilled were more or less for the use of looks. That was the main reason I was interested in them was for the look. Though my car is only going to be used for street use and car shows this kinda leaves me wondering which route I should still go with. I may stay with the reg rotors and eventually buy a c5 kit or baer rear kit. I am glad our board isn't like that, I would never post if that was the case! Thanks for the help, that gives me a different look.

      Andrew

      68LSS1
      Registered User
      Posts: 42
      (4/14/04 12:20 am)
      Reply Re: whoa, well that kinda gives me a better understanding.
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      30 pages, plus 3 in the new thread. I did learn something though. And it wasn't not to buy an Altima.

      69MyWay
      Registered User
      Posts: 7
      (5/21/04 7:41 am)
      Reply Re: Using larger drilled and slotted rotors
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      I am going to give a pair a shot on my 69. Going with the full C5 13" brakes. I am waiting on my adapter bracket right now and the rotors. I am not going to race the car on the track and it will see limited street use. My main desire is....Looks!

      The 6th gen Vette gets cross drilled rotos from the factory. They must not be all bad, or GM would not consider doing this (at least I hope).

      I am in the same situation on the rear. I am having a custom 9" built and will run 3rd or 4th gen F body discs. I assume I can just get an aftermarket cross drilled set to match. Otherwise it might look kind of stupid. So, I too am searching. My diff won't be finished for a few weeks and it will be MONTHS before I am ready to install. I do however want to have a plan ahead of time so I can be prepared.



      gmachinz
      Unregistered User
      (5/21/04 11:02 am)
      Reply FYI:
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      For those of you using 9" rears and Danas, look into TSM's e-brake kits. They utilize a small caliper/rotor which bolts to your rear diff. and it locks the driveshaft from spinning. It looks better than a factory type caliper linkage design IMO.-G

      Ripper
      Registered User
      Posts: 296
      (6/4/04 5:15 pm)
      Reply
      Re: FYI:
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      69myway: Porsche and Ferrari are also using cross drilled rotors... And both manufactures has confessed that it's styling and owner of both brands has problems with cracks in the discs...

      if you just in it for the looks, do as you want... But if you want to build something that actually works and that you can be proud of I would go for solid discs


      BT61
      Posts: 19
      (6/4/04 6:29 pm)
      Reply
      ezSupporter

      Re: FYI:
      --------------------------------------------------------------------------------
      We ran factory cross drilled Porsche rotors on our IMSA GTP light cars in the 80's. We replaced them when the cracks would connect the holes. I'm sure the cracks could have been machined out, but then the rotors would have been too thin for racing applications.

      69MyWay
      Registered User
      Posts: 11
      (6/7/04 3:49 am)
      Reply Re: FYI:
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      I am aware of the risk...but they look so darn kwellllll!!!!!!!!!!



      XcYZ
      Registered User
      Posts: 1211
      (6/7/04 5:58 am)
      Reply
      Re: FYI:
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      69MyWay, is it me, or is your UCA Jet-Hot coated?
      Scott
      My 69
      Lateral-g.net


      69MyWay
      Registered User
      Posts: 12
      (6/7/04 6:57 am)
      Reply Re: FYI:
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      Powder coated silver with powder coated clear coat on top.

      They call that finish mirror chrome.

      I will be doing the ford 9 rear axle in the same finish.

      The clear coat gives it that slick wet look.

      We did the custom roll bars in my 69 convertible vette in the exact same stuff.