Slotted vs drilled rotors
10-18-2020, 11:19 AM
#16
The Penguin King
Rennlist Member
Rennlist Member
So interesting to see some "new wave" perspective on "drilled" rotors. PAG ran them for decades as well as privateer teams running Porsches. Globally and with success. I ran them myself for a really long time.
What I usually say on this subject is "it depends."
I remember back in the 90's when I was running a 944 Turbo S that was a street/track car and sharing it with my wife. While back home in WI on a business trip I got to visit KMR, and we talked about braking systems. They advised a different factory proportioning valve and 965 rotors (with holes cast in)-- only 965 rotors from Porsche and not aftermarket. And we discussed ducting. I implemented some more advanced ducting. And we discussed pads, and they advised Pagid Orange. They has been running 944S2 cars in Firehawk, and were campaigning a 965 or two in IMSA alongside Rich M.'s very special 968. At the moment in time when I visited there, PAG was not running a factory team in the US.
Anyway, I always suggest folks think about brakes as a system, and to be wary of those that claim absolutes.
Certainly braking component and system designs and materials have evolved in the past 3 decades (since I started with this hobby) but two things I learned in year one (at my first PCA "meeting" in around 1988 where Bob Akin was the featured guest) still seem to be true: (i) be wary of absolute statements, and (ii) don't be afraid to get advice from experienced racing professionals.
We did not have the internet as a resource back then.
What I usually say on this subject is "it depends."
I remember back in the 90's when I was running a 944 Turbo S that was a street/track car and sharing it with my wife. While back home in WI on a business trip I got to visit KMR, and we talked about braking systems. They advised a different factory proportioning valve and 965 rotors (with holes cast in)-- only 965 rotors from Porsche and not aftermarket. And we discussed ducting. I implemented some more advanced ducting. And we discussed pads, and they advised Pagid Orange. They has been running 944S2 cars in Firehawk, and were campaigning a 965 or two in IMSA alongside Rich M.'s very special 968. At the moment in time when I visited there, PAG was not running a factory team in the US.
Anyway, I always suggest folks think about brakes as a system, and to be wary of those that claim absolutes.
Certainly braking component and system designs and materials have evolved in the past 3 decades (since I started with this hobby) but two things I learned in year one (at my first PCA "meeting" in around 1988 where Bob Akin was the featured guest) still seem to be true: (i) be wary of absolute statements, and (ii) don't be afraid to get advice from experienced racing professionals.
We did not have the internet as a resource back then.
10-18-2020, 01:15 PM
#17
Those rotors look ok to me. I don't see any big full length cracks. Can you feel the cracks with your fingernail? In my experience rotors get to a point like that pretty early on, but then maintain for quite bit afterward. Kind of moot then when they're effectively free, though. Just warranty them if it makes you more comfortable. I've been using the FCPEuro warranty for several years.
I'm running the Sebros and they're holding up well so far with Ferodo DS1 pads and RE71Rs or A052 street tires. I'm at six weekends on this set and at this rate they'd be good for six more. I'm an experienced driver and reasonably snappy.
I'm running the Sebros and they're holding up well so far with Ferodo DS1 pads and RE71Rs or A052 street tires. I'm at six weekends on this set and at this rate they'd be good for six more. I'm an experienced driver and reasonably snappy.
10-18-2020, 10:56 PM
#18
Burning Brakes
Maybe an obvious thing, but were the slotted rotors installed on the correct side? Those are left and right specific and the internal vanes/ventilation I believe are directional for proper cooling. Might be worth confirming.
10-19-2020, 04:00 AM
#19
Rennlist Member
10-19-2020, 10:58 AM
#20
Former Vendor
10-19-2020, 05:02 PM
#21
Rennlist Member
Non-drilled have more surface area for the pads to bite into, usually. Ran cross-drilled for a few years in my old 944T and was much better with the directional vane'd full surface cryo rotors I switched to. Also spent some time adding cooling for the rotors. made a big difference as well. Running Girodisc on the new 911 and was at Barber a couple of weeks ago and WOW, the 929's were biting very well. No noticeable fade. I did add the GT3 brake ducts to the front beforehand and I am adding the rear GT3 ducts to the rears this week, before heading to the Chinn RA even this weekend. Also adding new CSF rads on both sides and their center rad, plus a larger heat exchanger on the PDK, to keep the water temps lower. (thanks Goldcrest!)
10-19-2020, 06:34 PM
#23
Three Wheelin'
Thread Starter
10-19-2020, 07:59 PM
#24
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