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Replacement Rotors

the bruce

Go Kart Champion
So Sonny, same question. Why do all the OEM's go with drilled rotors on all their high performance car's then?


LOOKS. That's it.

At least by 95 %. Keep in mind there are difference between 'drilled' and 'drilled'.
Porsche rotors have casted holes, most ones are drilled after casting which hurts
the structur of the cast iron and weakens the rotor.


Incorrect. I see a large amount of drilled discs on Race cars and track cars. That is only with Iron however. Indy and F1 cars have switched to carbon and thus have removed the drilled holes. Plus Open wheels cars obviously have 0 issues with receiving adequate airflow to the brakes.

Despite popular belief gasses are still produced by modern brake pads particularly in the rain. However this is due to the semi-metallic pads interacting specifically with Iron. This is more common on the higher performance street and track pads that most of us use that intend to go to a track. Thus with the development of C rotors they have now become obsolete.

As to the comment earlier that no professional racers use slots. NASCAR use them extensively. See photo below:

The most interesting rotor design now is the wave rotor. The RS5 is using this design on Iron rotors. If you opt for the Carbon though they disappear.


I cannot fully agree, mate. ;)

By far most true race cars run slotted rotors (iron). I don't even know a serious
race car running drilled rotors.
Open wheel cars have similar cooling issues though.

Of course pads do produce gasses, but these surely can be removed through slots
sufficiently too. I also don't see any reason why pads should degass more in the rain.
There's just some film of water for the very first moment when you hit the brakes
and this film is also easily removed by the slots.
Even more most race cars use sintered pads which have much less gassing than the
pads most of us use.

The wave design which both RS4 and RS5 use is just looks and marketing. I'd prefer
Audi would make some proper brakes for the TT-RS which is known for it's weak
brakes due to bad rotor design (curved but not directional vanes, both sides share
the same type of rotor) instead of making such silly designs.

To be honest rotor design is a very complex task. Slotting and cross drilling is just
one (minor) point. Alloying of the iron, content of carbon, some amounts of copper
and molybdanium (on expensive discs), casting technology, heat treatment (as well
on expensive discs only), the precision of cutting and of course the design of the
cooling vanes, the design of the aluminium hub - this all is crucial for a really good
brake rotor. Surface machining is just one part of a long story.

I'd always prefer a cooler running 2-piece rotor with a sophisticated vane design
over a cheap standard disc with the latest kind slots and drilling.
 

DarkCloak

Banned
:confused:
LOOKS. That's it.

At least by 95 %. Keep in mind there are difference between 'drilled' and 'drilled'.
Porsche rotors have casted holes, most ones are drilled after casting which hurts
the structur of the cast iron and weakens the rotor.





I cannot fully agree, mate. ;)

By far most true race cars run slotted rotors (iron). I don't even know a serious
race car running drilled rotors.
Open wheel cars have similar cooling issues though.

Of course pads do produce gasses, but these surely can be removed through slots
sufficiently too. I also don't see any reason why pads should degass more in the rain.
There's just some film of water for the very first moment when you hit the brakes

and this film is also easily removed by the slots.
Even more most race cars use sintered pads which have much less gassing than the
pads most of us use.

The wave design which both RS4 and RS5 use is just looks and marketing. I'd prefer
Audi would make some proper brakes for the TT-RS which is known for it's weak
brakes due to bad rotor design (curved but not directional vanes, both sides share
the same type of rotor) instead of making such silly designs.

To be honest rotor design is a very complex task. Slotting and cross drilling is just
one (minor) point. Alloying of the iron, content of carbon, some amounts of copper
and molybdanium (on expensive discs), casting technology, heat treatment (as well
on expensive discs only), the precision of cutting and of course the design of the
cooling vanes, the design of the aluminium hub - this all is crucial for a really good
brake rotor. Surface machining is just one part of a long story.

I'd always prefer a cooler running 2-piece rotor with a sophisticated vane design
over a cheap standard disc with the latest kind slots and drilling.

It is not more gas from the pad it is water vapor. It is vaporized by being in the proximity of the disc. It does not actually need to be in contact just in the vicinity of the braking system. I use the term gas because that is water in the gaseous state.

Note that I am sure AF-MKVI was referring to holes pre-cast in the disc not drilled afterwards. Also. The Wave Rotor can't be used for style unless it is from someone with no sense of style they are a hideous eyesore!
 
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sprytdi

Ready to race!
In the past drilled rotors were very prone to cracking. Thankfully with advancment in technology, the process of drilling and the metallurgy of the rotor is much more scientific, leaving a rotor that is much more resilient to cracking and warping and corrosion. I have had a 2 sets of ssbc big bite drilled and slotted rotors on two different performance pickup's, those rotors have been abused towing, rallying, and stopping an 8000lb truck. They have never shown a sign of fatigue, one set I ran for appx 80k mi(2 sets of pads), the other set I've only had on for about twelve. They rock and I will never use a solid rotor again, although to all who were postulating about pad wear, yes, the pads wear out about 25% faster. Its worth it, and seems about right cuz i can stop in about 75% of the space it used to take, or 25% less stopping distance, 25% less life out of the pad, its a good trade.
 

AF-MKVI

Go Kart Champion
The Wave Rotor can't be used for style unless it is from someone with no sense of style they are a hideous eyesore!

The purpose of the wave rotor is reducing unsprung mass with no reduction in swept braking area, Audi released some technical info on the new design and each rotor is 2.8 lbs lighter because of this. There is zero gain in heat dissipation or braking ability because of the new design.
 

DarkCloak

Banned
The purpose of the wave rotor is reducing unsprung mass with no reduction in swept braking area, Audi released some technical info on the new design and each rotor is 2.8 lbs lighter because of this. There is zero gain in heat dissipation or braking ability because of the new design.

Thanks man.
 

THISFCKINGUY

Ready to race!
Holy shit lots of info here...I was thinking slotted when the time comes, but so much debate I migjt just stay oem rotors, SS lines and some good pads, stoptech or hawk even.
 

DarienMidnight

Ready to race!
How long are oem mk6 gti rotors supposed to last anyway ? Mines is 2012 and they are currently looking like they have cracking lines on them
 

elcid86

Passed Driver's Ed
How long are oem mk6 gti rotors supposed to last anyway ? Mines is 2012 and they are currently looking like they have cracking lines on them

We changed the pads and rear hubs on my son's '12 GTI last night. The rotors look roached. They are on our list to do in the next few months. (car has 109k on it)
 

DarienMidnight

Ready to race!
Mine's have 52 on 53k miles .did a few hard ..very hard braking the last couple months . Racing all types of cars . Pads are fine rotors are my concern . You know of any good upgraded rotors? I don't really wanna go oem lol.or maybe I should ..not too sure


We changed the pads and rear hubs on my son's '12 GTI last night. The rotors look roached. They are on our list to do in the next few months. (car has 109k on it)
 

1ashchuckton

Autocross Champion
I ran Stop Tech slotted cryo treated rotors on my MINI Cooper S. They wore very well, after many track days & back road miles they still looked great. I know these are not cheap, but I'd say they lasted twice as long & performed much better that the oem rotors. When my GTI needs rotors I'll buy these again.

https://www.tirerack.com/brakes/brakes.jsp?make=StopTech&model=Sport+Slotted+Cryo-Treated+Rotor&group=Sport+Slotted+Cryo-Treated+Rotor&partNum=126.33098CSL&autoMake=Volkswagen&autoModel=GTI&autoYear=2013&autoModClar=2-Door
 

DarienMidnight

Ready to race!
I ran Stop Tech slotted cryo treated rotors on my MINI Cooper S. They wore very well, after many track days & back road miles they still looked great. I know these are not cheap, but I'd say they lasted twice as long & performed much better that the oem rotors. When my GTI needs rotors I'll buy these again.

https://www.tirerack.com/brakes/brakes.jsp?make=StopTech&model=Sport+Slotted+Cryo-Treated+Rotor&group=Sport+Slotted+Cryo-Treated+Rotor&partNum=126.33098CSL&autoMake=Volkswagen&autoModel=GTI&autoYear=2013&autoModClar=2-Door

THANKS SO MUCH MAN . it's like the car's brake's feel like a locomotive train now smh. Have to get them done asap
 

DarienMidnight

Ready to race!
I ran Stop Tech slotted cryo treated rotors on my MINI Cooper S. They wore very well, after many track days & back road miles they still looked great. I know these are not cheap, but I'd say they lasted twice as long & performed much better that the oem rotors. When my GTI needs rotors I'll buy these again.

https://www.tirerack.com/brakes/brakes.jsp?make=StopTech&model=Sport+Slotted+Cryo-Treated+Rotor&group=Sport+Slotted+Cryo-Treated+Rotor&partNum=126.33098CSL&autoMake=Volkswagen&autoModel=GTI&autoYear=2013&autoModClar=2-Door

Do you know the name and brand of our OEM rotors and pads ? And your stop tech cyro is the closet to OEM but maybe a level up ? That's what I want ..
 
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