I keep cracking rotors on my G car - suggestions?
07-05-2007, 05:33 PM
#31
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Originally Posted by Larry Herman
IMHO it most likely has to do with the combination of the immediate rotor surface temperature and the overall amount of brake cooling. A differential in temperature with the metal itself will cause cracking due to the differing amount of expansion.
When I raced my old Carrera, I ran Ferodo Asbestos Free pads, and thought it didn't stop the best (read higher entry speeds
) they never faded and I ran for 9 years on the same set of rotors. No BS. I did have a cool-brake kit on it.
When I changed to PF97s in 1998, I started to experience all kinds of problems. Yes I had a good deal better braking performance, but it came at the expense of the occasional softening and pulsating pedal, fried caliper seals every other event, and cracked rotors every third season. The PF pads were just generating too much friction for the system to handle. I feel that the smaller pads, when forced to brake at the limit of the sticky R tires, will produce some really high localized temperatures at the face of the rotor, as opposed to bigger brakes, which will spread a lower temperature across a larger area. Maybe that's why they are failing so quickly.
When I raced my old Carrera, I ran Ferodo Asbestos Free pads, and thought it didn't stop the best (read higher entry speeds
) they never faded and I ran for 9 years on the same set of rotors. No BS. I did have a cool-brake kit on it.When I changed to PF97s in 1998, I started to experience all kinds of problems. Yes I had a good deal better braking performance, but it came at the expense of the occasional softening and pulsating pedal, fried caliper seals every other event, and cracked rotors every third season. The PF pads were just generating too much friction for the system to handle. I feel that the smaller pads, when forced to brake at the limit of the sticky R tires, will produce some really high localized temperatures at the face of the rotor, as opposed to bigger brakes, which will spread a lower temperature across a larger area. Maybe that's why they are failing so quickly.
07-05-2007, 05:45 PM
#33
Brakes are for wimps. It is for that exact reason that Chuck Norris removed the brakes entirely from his G class race car. Unfortunately, the rotors cracked anyway out of pure terror.
07-05-2007, 05:50 PM
#34
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Originally Posted by 1957 356
Intersting stuff Larry. Maybe I should be experimenting with some different pads. I have had to rebuild my calipers twice since the end of last season. It's also interesting that these rotors cracked in two days and they were the first two days I've run Hoosiers. My lap times were a lot better and I was experimenting with braking much later.
07-05-2007, 05:50 PM
#35
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Chuck Norris brake? Never...the road straightens itself out in front of him out of respect!
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Larry Herman
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1994 RS America Club Racer
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1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
07-05-2007, 05:51 PM
#36
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wow, a chuck norris blast! good job TD (edit - and Larry)
BTW, i have some kind of similar issue now. I just bought my second set of new rotors for year. In previous years, a single pair has lasted the entire season or more. I haven't changed a thing on the car other than droving faster. The set I am replacing had small cracks leading to bad vibrations after just 10 days.
BTW, i have some kind of similar issue now. I just bought my second set of new rotors for year. In previous years, a single pair has lasted the entire season or more. I haven't changed a thing on the car other than droving faster. The set I am replacing had small cracks leading to bad vibrations after just 10 days.
Last edited by Mike Buck; 07-05-2007 at 06:13 PM. Reason: add t to edit lol
07-05-2007, 06:03 PM
#37
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Stock calipers? Have you tried just plain stock Porsche rotors. The ones from the dealer.. Not from anywhere else. I had great luck at the glen with those on my 86 Carrera and Pagid orange.
Don
Don
07-05-2007, 06:09 PM
#38
I'll have to confirm which tonight but if you want a Hawk pad to try mine are either the "Black" or "HT10" compound.
I've heard the "Blue" compound is very hard on rotors.
I've heard the "Blue" compound is very hard on rotors.
07-05-2007, 06:32 PM
#39
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Chuck Norris waxes Jack Bauer's back.
07-05-2007, 07:02 PM
#41
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DON'T TEMPT ME:
http://www.notrly.com/jackbauer/index.php?topthirty
My personal favorite of those 100: If Jack Bauer had been a Spartan, the movie would have been called "1".
http://www.notrly.com/jackbauer/index.php?topthirty
My personal favorite of those 100: If Jack Bauer had been a Spartan, the movie would have been called "1".
07-05-2007, 07:11 PM
#43
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This should be a t-shirt:
07-05-2007, 07:41 PM
#45
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Sorry I didn't see this sooner Sean I have been in the garage starting to rebuild my rear calipers and changing the rotors.
My car has stock calipers. The front are stock rotors so far no cracks at all. I have cooling ducts going to the front calipers as well. I have been using Hawk blue pads since last year. No problems.
On the rear I tried the drilled rotors and came home this past weekend with cracks through the outer edge like you discribe. I have roughly 14 track days on them. No cooling to these monstrous rear calipers.
I just put Powerslots on the rear. If they crack I will just go back to the oem rotors. I did notice that the part numbering on the outer edge of the Powerslot rotors is near identical to the drilled rotors along with Made in Germany. So I am guessing the Powerslot folks are buying the same blanks and putting their slot on them.
FWIW the tracks I ran were CMP, VIR, Summit Point, Rockingham, and Lowes with the above setup.
I plan to try Pagid Blacks this go around. I'll go take a picture of my crack.
My car has stock calipers. The front are stock rotors so far no cracks at all. I have cooling ducts going to the front calipers as well. I have been using Hawk blue pads since last year. No problems.
On the rear I tried the drilled rotors and came home this past weekend with cracks through the outer edge like you discribe. I have roughly 14 track days on them. No cooling to these monstrous rear calipers.
I just put Powerslots on the rear. If they crack I will just go back to the oem rotors. I did notice that the part numbering on the outer edge of the Powerslot rotors is near identical to the drilled rotors along with Made in Germany. So I am guessing the Powerslot folks are buying the same blanks and putting their slot on them.
FWIW the tracks I ran were CMP, VIR, Summit Point, Rockingham, and Lowes with the above setup.
I plan to try Pagid Blacks this go around. I'll go take a picture of my crack.