Front Rotors Cracking...???
06-03-2011, 08:58 AM
#31
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So I might have been replacing too often. I was told at one point even if the holes didn't connect, if the crack from one line of holes at a certain diameter went as high as the next line of holes at a certain diameter, even if the holes didn't connect, it was time to replace. If holes connecting OR crack to edge is the rule, I should get more life out of my rotors...
Id go by the pictures posted earlier in this thread and stick with it. Id hate for you to lock up one of your front wheels and spin into a wall just to save 300 bucks.
06-03-2011, 09:01 AM
#32
Burning Brakes
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Interesting. Rotor failure is no joke.
I remember visiting KMR in 1994 which was toward the beginning of the heavy car period. Pagid oranges were a pretty new thing then. KMR learned pretty quickly to only use and recommend Porsche rotors from boxes that read Porsche. From the dealer. I see no reason why that would have changed for this type of application. I sure stuck to that advice with my heavy 360 bhp 951 track/race car.
Now the use of NASCAR stuff is also interesting. I do not find big, heavy rotors exciting in any way. There are plenty of other things to get excited about on the internet. Plenty. Certainly one responder here is aware of that.
I want the lightest brakes I can run and still get effectiveness for my car. It weights under 2000 pounds, runs slicks and has a 350 bhp 3.8 liter engine. I can run 930 calipers on the front and super lightweight and cheap Wilwood rotors. Effective and light. My friend had the same car for a while but with a 700 bhp 3.8 tt. He could run nearly the same brake set up without issues. Why? Light car. So I'd only want things like fans and water cooling and enormous rotors if I had to have them.
Anyway, I suggest being conservative with cracked rotors, and if in doubt consult a local pro with Porsche racing experience, like I did with KMR back in '94. And for those heavy stockish cars if choosing between aftermarket and Porsche, only use the Porsche rotors out of Porsche boxes. Not all Zimmermans, et cetera are the same... made with the same materials and tolerances, et cetera.
I remember visiting KMR in 1994 which was toward the beginning of the heavy car period. Pagid oranges were a pretty new thing then. KMR learned pretty quickly to only use and recommend Porsche rotors from boxes that read Porsche. From the dealer. I see no reason why that would have changed for this type of application. I sure stuck to that advice with my heavy 360 bhp 951 track/race car.
Now the use of NASCAR stuff is also interesting. I do not find big, heavy rotors exciting in any way. There are plenty of other things to get excited about on the internet. Plenty. Certainly one responder here is aware of that.
I want the lightest brakes I can run and still get effectiveness for my car. It weights under 2000 pounds, runs slicks and has a 350 bhp 3.8 liter engine. I can run 930 calipers on the front and super lightweight and cheap Wilwood rotors. Effective and light. My friend had the same car for a while but with a 700 bhp 3.8 tt. He could run nearly the same brake set up without issues. Why? Light car. So I'd only want things like fans and water cooling and enormous rotors if I had to have them.
Anyway, I suggest being conservative with cracked rotors, and if in doubt consult a local pro with Porsche racing experience, like I did with KMR back in '94. And for those heavy stockish cars if choosing between aftermarket and Porsche, only use the Porsche rotors out of Porsche boxes. Not all Zimmermans, et cetera are the same... made with the same materials and tolerances, et cetera.
06-08-2011, 12:07 AM
#35
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Not trying to belabor the point, nor to be penny wise and toast the car...but the cracks don't seem to have met the criteria...5-7mm, connecting holes, or to the edge?
06-08-2011, 12:25 AM
#36
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06-08-2011, 01:49 AM
#38
Those are fine. Cracks aren't connected nor touching the edge.
Take a set of rotors to the track with you. If you feel a pulsing under braking, you've cracked them to the edge. Then replace them between sessions.
Take a set of rotors to the track with you. If you feel a pulsing under braking, you've cracked them to the edge. Then replace them between sessions.
06-08-2011, 08:49 AM
#39
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First picture doesent scare me but the second one is pushing my comfort zone. I would replace them when it looked like I could stick something into the crack vrs a hair line fracture.
Id move on with those IMO.
Id move on with those IMO.
06-08-2011, 08:58 AM
#40
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Those are just about done. You could probably get another day out of them. They are going need replacing anyway so I would just do it now. Have you measured the thickness? Looking at the lip on the outer edge in the second photo, they might be out of spec anyway. Plus you already have them off the car, so you've already done half the job.
How many events are you getting out of a set of rotors? What pads and fluid are you running? If not using them already, try the Pagid yellows. They are gentle on the rotors and perform well. They don't have the higher torque of the Pagid RS14 or the Performance Friction 01 but they are easier on the rest of the brake system.
How many events are you getting out of a set of rotors? What pads and fluid are you running? If not using them already, try the Pagid yellows. They are gentle on the rotors and perform well. They don't have the higher torque of the Pagid RS14 or the Performance Friction 01 but they are easier on the rest of the brake system.
Last edited by Carrera51; 06-08-2011 at 09:19 AM.
06-08-2011, 10:22 AM
#41
Race Director
They are fine for the 924S. However don't waste money on drilled rotors for the 944. Heck I use cheap chinese made rotors on my 944-spec. They work just fine. The 993 is a different application.
06-08-2011, 11:10 AM
#42
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Yeah, I had taken them off ready to toss them, but reading some of the posts I wasn't so sure. Figured I'd ask. I'd have to look back at my notes, but no more than 10-15 days, which is sort of a bummer. I'm trying to put the AJUSA brake cooling ducts, but I can't figure out how to install them. Also a bummer.
Pagid yellow all around.
Rears I haven't replaced in at least 20 days, and they are at I think 24mm thickness (I didn't measure the fronts but will out of curiosity before I toss them.
Pagid yellow all around.
Rears I haven't replaced in at least 20 days, and they are at I think 24mm thickness (I didn't measure the fronts but will out of curiosity before I toss them.
06-08-2011, 12:46 PM
#43
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06-08-2011, 03:29 PM
#44
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http://www.shw.de/
06-08-2011, 03:39 PM
#45
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In the lower picture, at about 7:00 I see small cracks connecting 2 holes. Having seen an RS America totaled at the end of the back straight of Mid Ohio a few years ago because of a cracked rotor, I favor being safe. What is the value of one more day on old rotors? $20-30? saved?