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03-22-2004, 03:38 PM
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#766
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Regular User
Join Date: Sep 2003
Location: Ann Arbor, Michigan, USA/ Bloomington, IN, USA
Posts: 2,624
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coombsie66...I'm sure you've already thought of this or read it, but personally, I think that it probably has a great deal to do with cooling...you see, the holes have much greater total edge area than do the slots on a slotted rotor...even though it weakens the disk a fair amount, it is also quite effective at reducing the amount of heat retained, and as a result, helps to make heavy braking a repeatable, relatively fade-free experience.
You might also note that Aston Martin, Lamborghini, Maserati, Bugatti, Ford, Jaguar, Lotus, Mclaren, Mercedes, MG, Noble, Pagani...etc...ad nauseum...also use cross drilled brakes on their high-performance machines...so they must have a fairly significant benefit from a performance standpoint.
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my Hindibonics-speaking Indian roommate--"Dawgs, do you have any idea how much bacteria that would take?"
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03-22-2004, 03:49 PM
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#767
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Regular User
Join Date: Dec 2003
Location: New York City/Haverford, PA
Posts: 791
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sorry you won´t get any prototype pics of upcomming models...
check "Pn" you ´ll find quite some pics and infos on the TOP2 ( 997TT) model...
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Do you know if it will be released this summer stateside? My father is in a midlife crisis and has a 1998 Audi A8 and for the past 5 years has been drooling over the Turbo. He is a huge car enthusiast, and since the Audi is getting old, finally has decided it is time to make up for lost speed.
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"You can get a lot much farther with a kind word and a gun, than you can with a kind word alone"
-Al capone
"Time is a versitile performer: it flies, marches, heals all wounds, runs out and will tell"
-Franklin Jones
^The definition of grip. Nav+Bose (standard) Arctic Silver on Blue, Heaven on Earth. '05 911 Turbo^
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03-22-2004, 03:52 PM
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#768
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Regular User
Join Date: Dec 2003
Location: New York City/Haverford, PA
Posts: 791
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kinda off topic, i know, but that´s why we love "Sport Auto" so much, because of covers and reports like this....
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Ok, is the SLR lost?
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"You can get a lot much farther with a kind word and a gun, than you can with a kind word alone"
-Al capone
"Time is a versitile performer: it flies, marches, heals all wounds, runs out and will tell"
-Franklin Jones
^The definition of grip. Nav+Bose (standard) Arctic Silver on Blue, Heaven on Earth. '05 911 Turbo^
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03-22-2004, 04:29 PM
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#769
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Regular User
Join Date: Jul 2003
Location: London
Posts: 3,381
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On the drilled brake issue....I am no expert, so don't shoot me if I am wrong, but:
Are there not some new ones in development to overcome the classic weakness and stress issues. Instead of the traditional round holes, a company (I can't remember who) have been using oval shapes. Due to the different -insert technical lingo here- they are less prone to stess failure......
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03-22-2004, 04:52 PM
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#770
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Regular User
Join Date: Jun 2003
Location: somerset/london
Posts: 1,636
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Originally Posted by Vansquish
coombsie66...I'm sure you've already thought of this or read it, but personally, I think that it probably has a great deal to do with cooling...you see, the holes have much greater total edge area than do the slots on a slotted rotor...even though it weakens the disk a fair amount, it is also quite effective at reducing the amount of heat retained, and as a result, helps to make heavy braking a repeatable, relatively fade-free experience.
You might also note that Aston Martin, Lamborghini, Maserati, Bugatti, Ford, Jaguar, Lotus, Mclaren, Mercedes, MG, Noble, Pagani...etc...ad nauseum...also use cross drilled brakes on their high-performance machines...so they must have a fairly significant benefit from a performance standpoint.
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Yeah, i cant understand it, and om just after a good theoretical engineering explaination, cus it doesnt all add up in my head!!!!
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03-22-2004, 06:25 PM
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#771
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Regular User
Join Date: Jun 2003
Location: Belgium
Posts: 1,668
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Originally Posted by st-anger
kinda off topic, i know, but that´s why we love " Sport Auto" so much, because of covers and reports like this.... :shock: 
sorry guys( coombsie66&crasherror), don´t have time to answer your questions right now, i´m really busy, maybe tomorrow...  ops: |
Wow, that surely seems to be quite a cool article. Euhm, I know it's a lot to ask from a busy man like you but if you have some time... could you maybe scan it ops: ? I would love to read it. Ok my German isn't that great, but good enough to understand the most of it.
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03-23-2004, 02:15 AM
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#772
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Regular User
Join Date: Oct 2003
Location: United States
Posts: 408
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I located a site that has scans of various articles profiling cars being tracked at the Nurbergring. My favorite article is "At the 'Ring with Röhrl (Car, October 1999)"
THe article is about driving around with WR in a GT3 on the Nurbergring. Check it out and the other articles as well.
http://www.jwhubbers.nl/ring/misc/print.php
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03-23-2004, 05:45 AM
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#773
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Regular User
Join Date: Jun 2003
Location: Belgium
Posts: 1,668
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Originally Posted by lakatu
I located a site that has scans of various articles profiling cars being tracked at the Nurbergring. My favorite article is "At the 'Ring with Röhrl (Car, October 1999)"
THe article is about driving around with WR in a GT3 on the Nurbergring. Check it out and the other articles as well.
http://www.jwhubbers.nl/ring/misc/print.php |
Nice links thx!! I've only got one of those I think!!
Will surely save them to my hd later.
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03-23-2004, 11:48 AM
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#774
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Regular User
Join Date: Jun 2003
Location: Toronto, Canada.
Posts: 385
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Originally Posted by st-anger
kinda off topic, i know, but that´s why we love " Sport Auto" so much, because of covers and reports like this.... :shock:
sorry guys( coombsie66&crasherror), don´t have time to answer your questions right now, i´m really busy, maybe tomorrow... ops: |
It's the 23rd which equals tomorrow.............. info!!!!
Just kidding, but that looks really awesome.
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Formerly known as SG Blade.
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03-23-2004, 04:19 PM
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#775
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Regular User
Join Date: Jun 2003
Location: AT
Posts: 1,611
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again, sorry guys i just have some minutes left but i´ll try to quickly answer some questions...
yep, Crasherror, PAG is running a facility in Troy, Michigan, check this > [email protected]< for further information...
sorry S.Tomwe won´t see the 997TT before +/- 2006, but there´s some good news as well, it´s very likely that we´ll see a 5 in front of the performance figure... 
i´ll see what i can do for ya zipp, plz be patient...
coombs, i don´t want to answer your question in a hurry, ´couse i know you´d like to have a more extensive answer since you´re kinda into tech stuff, so i think i´ll take some time tomorrow to answer your question a bit more precise than just yes/no bla bla bla.... 
:x ...have to leave now...
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03-23-2004, 05:53 PM
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#777
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Regular User
Join Date: Jun 2003
Location: Belgium
Posts: 1,668
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Originally Posted by st-anger
i´ll see what i can do for ya zipp, plz be patient...
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thx, appreciate it
take your time
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03-23-2004, 07:39 PM
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#778
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Regular User
Join Date: Jun 2003
Location: somerset/london
Posts: 1,636
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Thanx st anger, yeah theres no hurry, im just interested, and i dont like proclaiming things unless i know the whole story, so take your time! I await in anticipation!
'couse i know you´d like to have a more extensive answer since you´re kinda into tech stuff'
lol, kinda into the tech stuff!! Its a way of life for me now, i have little choice in teh matter!!
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03-23-2004, 07:43 PM
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#779
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Regular User
Join Date: Jun 2003
Location: somerset/london
Posts: 1,636
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Originally Posted by nthfinity
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Yeah, i was kinda aware of that thread since i posted in it right at the start!!!!!!!! :roll: lol, i appreciate the thought tho, cheers.
Yeah that doesnt explain conclusively to me why most manufacturers use cross-drilled discs on their high performance vehicles, hence i came here, as porsche are renound for their brakes.
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03-24-2004, 01:25 PM
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#780
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Regular User
Join Date: Jun 2003
Location: AT
Posts: 1,611
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Originally Posted by coombsie66
^^^^ HELL YEAH, they still sound sooooo good.
St-anger, after reading a lot of info on cross drilling brake discs, i can only come ot the conclusion that the disadvantages far outweigh any benifits they might show. So why is it that porsche still cross-drill their cast discs? Do they cast the holes into them, and radius all edges to reduce the stress concentrations and disruptions to the crystal structure?! Cus i can argue till im blue in teh face wiv some people that drilled discs do not perform better, but as long as they can all come back and say so why do porsche and ferrari, etc use them!?! Im stuffed!
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all in all you´re right, cross drilled rotors doesn´t have a certain benefit so that i´d be important to have them for better braking performance or something like this…
although i´ve to admit that I really don´t know everything about brakes and braking ´cause I more the engine - drivetrain guy i´ll try to do my best
Porsche introduced the first cross drilled rotors back in 1970 on a Porsche 908/3, mainly to save weight, so the 908/3 had an incredible power to weight ratio of 1.55kg per hp, another reason, the (early) brake pads had a kinda high tendency of out-gassing, which is one of the most common sources of heat from braking. it´s from the gases produced by the bonding agents of the brake pad burning off. under severe braking, this can actually produce a boundary layer of gas that pushes the pad away from the rotor, which can lead to excessive brake fade. the cross-drilled holes or slots in a rotor provide an escape path for these gasses and allow the pad to stay in contact with the rotor. as well as de-gassing, cross drilling or slotting will provide better wet weather braking as water os produced steam is swept through the holes, or down the slots. nowadays pads don´t have this tendency that much any more. another advantage is that cross drilled rotors deglaze the brake pads, so initial braking bite is improved, but this has nothing to do with better/harder braking itself, it just increases friction…as already mentioned above the heat thing is a very interesting one, so no they aren´t cooler because they´re drilled, maybe a bit, but actually, as already mentioned, the heat transport is more efficient in solid rotors, on the other hand i´ve talked to some techs here and they´ve told me that drilled one´s are better under really really hot conditions e.g. racing, rotors without holes are ~30-90°C hotter than drilled rotors, so actually we can´t say this or that rotors are “cooler”…
the problem of stress cracks on cross drilled rotors is undisputable, it´s the expense for the lower weight…
so, there´d be even more to tell but I think we all see the point, in sportscars like Porsche, Ferrari, … cross drilled rotors are mainly used to save some weight AND…they simply look sportier than solid rotors like mounted on every Golf, sure they´ve some advantages but really not THE breakthrough performance-related, and another important point nobody´s talking about, one hand is washing the other one: rotors and pads wear more quickly with holes in the rotors, so you´ll have to visit your garage more often with cross drilled braking system…
hope this helps a bit, sorry i´m in a hurry so plz don´t be too strict
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