Wednesday, May 20, 2009 - 01:36 am, by: Peter Nitschke(Pen)
Drilling weakens the disk. Either way though, it's not going to make a huge difference to your brakes, Choice of pads will have a bigger effect for example, in both stopping power and handling high temperatures.
Wednesday, May 20, 2009 - 10:33 am, by: Ben Lipman(Ben12a)
This is an interesting argument.
In Australia, everyone goes for slotted disks. Slotting allows the hot gas that is generated between the pad face and disc to escape, increasing bite and the braking performance. It is also believed to help 'wipe' the pad clean.
In the USA and Europe, the popular trend is towards drilled rotors, or drilled and slotted. Drilling aids rotor cooling and also allows gases to escape as per slotting. Drilled and slotted does the lot.
A lot of very high end production sports cars have drilled rotors, especially in Europe. (Ferrari, Lambo, etc) I can only assume these companies know what they are doing and have tested extensively. I would like to believe that their GT racing programs don't spend a lot of time thinking about the "show" quality of their braking package.
There was a problem with drilled rotors cracking on a car back in the 90's in Australia. It might have been a WRX or something. You know how these things go, once some thing has failed and the general public pick up on it, it is very hard for that product to ever flourish again.
I believe good quality products (drilled or slotted) will not fail. Poor quality products will fail regardless of being drilled or slotted. For the record, I cracked a stock standard, non drilled or slotted rotor after one track day in the Rx-7. I bought locally made RDA slotted disks (always replace in pairs!) and never had a problem.
I am currently using the standard TT package at the track, albeit with a lightened car. I am trying to figure out what I'll do with brakes in the future, with a full Supra conversion over half the cost of a true high performance brake setup. I think I might try some slotted rotors on the standard brakes before committing to a big spend. I am on a budget...
Wednesday, May 20, 2009 - 12:34 pm, by: James Johnson(Jimbo)
I'm with Peter, drilled weaken the disc's, slotted are designed for track use and effectively take little "chunks" of you're pad off each time to keep them clean and provide better grip from any dust build up. It all depends on you're use to you're application. I'm getting some supra stoppers soon and intend to do some track work but will only use decent pads with standard disc's.
Wednesday, May 20, 2009 - 05:42 pm, by: Ben Lipman(Ben12a)
James, drilling can only weaken the disc, if it was not designed to be drilled in the first place. Slots also weaken the disc, as does any break in the surface of the rotor. Poorly designed or applied slots will put the rotor out of balance and it runs the risk of self destructing.
Disregarding a piece of race derived hardware out of hand based on myth and rumour is just silly. Have a look at any GT race car, many open wheelers (not using something exotic) and any high end sports car outside Australia and the have drilled rotors.
Can any fool drill his stock rotors and hope for better brakes? NO. But if a reputable company such as Rotora, DBA, RDA, and many others offer a drilled rotor as a replacement, then you can rest assured it is up to the task, and in Australia at least meets an ADR, minimum spec or standard of some sort.
Wednesday, May 20, 2009 - 07:06 pm, by: Scott Casey(V8soarer_1991)
You will find that the rotor thickness of the 2 sides of the disc that brembo ferrari, lambo, porche etc. are thicker than the pbr, rda, dba etc use. which allows the rotor to take more heat for longer without cracking.
side - cooling fin - side [ ]-[ ] ferreri etc. []-[] pbr, dba etc. (view from the front of the disc)
Wednesday, May 20, 2009 - 07:21 pm, by: Nathan Smith(Zanjara)
Funny how the DBA drilled and slotted rotors crack under heat. Was proven on the V8 supercars a few years back. Most of your high end market supercars use dimpled rotors not drilled... There is a difference between the two. drilled goes all the way through the rotor where dimpled dont.
Most of your high end race cars also use carbon fibre rotors and after so many laps they do brake it was proven again on the C06 corvette while racing a rotor blew and they had to retire the race after leading for so many hours.
Also the standard rotor in which you broke would be due to the fact that it was too hot that would of been the reason why it cracked. rotors can only with hold so much heat before they do end up cracking.
RDA would be the best bet for rotors at lest you know they are a full steel rotor unlike some DBA rotors which are cast.
For an everyday street car slotted rotors do the job if you want to help get rid of the gas buildup between the rotor face and pads. Also a good pad will always aid in good brakes.
Peter Nitschke Junk Filterer South Australia UZZ30 UZZ31
Wednesday, May 20, 2009 - 08:14 pm, by: Peter Nitschke(Pen)
High end rotors with holes are actually cast that way, as opposed to being drilled later. There is a big difference in how these rotors then handle heat and stress.
Compare a factory built convertible versus running a chainsaw through the pillars.
Rotor manufacturers, eg DBA also recommend that drilled NOT be used for track days.
Good braking is a complex subject, there isn't a simple formula for best results. Some slotted rotors don't actually have the slots go to the edge of the rotor, so they aren't actually a gas conduit, but possible a gas storage slot which then dumps the gas as it clears the pad surface.
There is a lot of scat talked about brakes, often not based on much real factual information.
Seriously, the best improvement for your brakes, is really good pads and brake fluid.
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