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      07-13-2012, 09:15 AM   #1
LiM3y
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Track Rotor Wear

I thought I would post this up.

My OEM rotors have done enough mileage (20K) to be close to replacing, based on previous changes. Being out of warranty, I bought a digital brake measuring caliper to check my rotor thickness. In two days at NJMP in the advanced group, 4 x 25 minute sessions, plus about 1.5K normal driving, I used 0.1 mm of brake rotor with PFC-01 pads. The right front rotor was at ~29.00, and now it is at ~28.90 (28.4 is the minimum thickness). The left rotor is more warn than the right, not surprisingly, by about 0.1mm difference. The measurements were consistent at the outer, middle and inside measuring at 8 locations (every two drilled lines).

The rotors are 30mm out of the box.

PS The car passed 066666 last night on the way home.... The new M3 can't come soon enough. I think I will pass on the Lime Rock Special Edition E92
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      07-13-2012, 09:56 AM   #2
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Are you planning on replacing with OEM rotors or a direct replacement such as what Performance Friction offers? I appreciate the information, thinking it may just be time to take a caliper to my rotors! I just recently hit 60,000km and have been thinking about the PF replacements once the time comes, no comment on the Lime Rock Park Edition
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Last edited by DJDeez; 07-13-2012 at 10:30 AM. Reason: Confused Performance Friction with StopTech!
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      07-13-2012, 09:58 AM   #3
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Very close to gotcha, and/or decision time. To run or not to run. I am chicken, so I doubt I would be comfortable tracking the car with the rotors that close to oh oh. How many events do you plan to run before new M3 arrives? If only one, then you might be able to baby it around and still get it home, but if the fangs are going to appear, let your pocket book be your guide. As an aside, there is always Hertz or Avis.
vz
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      07-13-2012, 11:46 AM   #4
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I am close to replacing the rotors with OEM ones. They have done the job well enough with the right pads so far. I was thinking about the PFC rotors, but will leave the car stock fopr the time being. I was also going to put in some brake ducts, but despite getting all the bits, decided not to start hacking holes in the car for about 1 year's use and a few track days.

I thought I would need to swap rotors now, but I have some time left. They are about 75% used based on the starting thickness and minimum thickness. They have ~15 track days on them plus ~20K miles. I will check them again before the next event to make sure they are okay. There are no signs of cracking at the moment. My last set got micro cracks and they were swapped under warranty. I am on the conservative side with replacing worn items.

I am now planning in getting the next gen M3 next year, rather than a late E92 (unless there are awesome deals before that)
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      07-13-2012, 01:00 PM   #5
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Quote:
I am now planning in getting the next gen M3 next year, rather than a late E92 (unless there are awesome deals before that)
Sounds like a smart idea, OEM, and the correct one. When you eventually sell it (or trade) stock is better than modified. I too am sort of on the fence, as my warranty is up in March 2013. To wait for the next gen M3, buy a 2013, or switch cars all together. GT3RS is a canidate.
See ya at a VIR event soon?
vz
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      07-13-2012, 01:18 PM   #6
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Quote:
Originally Posted by von_zoom View Post
Sounds like a smart idea, OEM, and the correct one. When you eventually sell it (or trade) stock is better than modified. I too am sort of on the fence, as my warranty is up in March 2013. To wait for the next gen M3, buy a 2013, or switch cars all together. GT3RS is a canidate.
See ya at a VIR event soon?
vz
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      07-17-2012, 05:32 PM   #7
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Quote:
Originally Posted by von_zoom View Post
Sounds like a smart idea, OEM, and the correct one. When you eventually sell it (or trade) stock is better than modified. I too am sort of on the fence, as my warranty is up in March 2013. To wait for the next gen M3, buy a 2013, or switch cars all together. GT3RS is a canidate.
See ya at a VIR event soon?
vz
GT3 all the way Doc!
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      07-17-2012, 06:22 PM   #8
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All I need Ashley is $$$$. Do you have any interest in sponsorship :-)
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      07-17-2012, 07:29 PM   #9
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Good data, thanks for sharing. I take it these rotors get too thin before they crack then? I've had issues with track rotors (especially drilled) cracking before they could get to min thickness.
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      07-17-2012, 08:11 PM   #10
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Quote:
Originally Posted by LiM3y View Post
I thought I would post this up.

My OEM rotors have done enough mileage (20K) to be close to replacing, based on previous changes. Being out of warranty, I bought a digital brake measuring caliper to check my rotor thickness. In two days at NJMP in the advanced group, 4 x 25 minute sessions, plus about 1.5K normal driving, I used 0.1 mm of brake rotor with PFC-01 pads. The right front rotor was at ~29.00, and now it is at ~28.90 (28.4 is the minimum thickness). The left rotor is more warn than the right, not surprisingly, by about 0.1mm difference. The measurements were consistent at the outer, middle and inside measuring at 8 locations (every two drilled lines).

The rotors are 30mm out of the box.

PS The car passed 066666 last night on the way home.... The new M3 can't come soon enough. I think I will pass on the Lime Rock Special Edition E92
Good info for comparison--thanks for posting. I'm on my original rotors from my StopTech ST60/ST40 BBK. They've seen 16,000 miles, about 20 track days, two sets of StopTech Street Performance pads, and have used up half of the material on a set of Pagid RS29s. Since I change my tires for the track and have access to the rotors, I decided like you to get a quality digital caliper to measure rotor thickness routinely. The fronts started at 35 mm and are now at 34.1-34.2 mm. StopTech recommends replacing them after 2 mm of wear, so at 33 mm.

As far as the Lime Rock Special Edition goes, I think BMW missed the boat by releasing it in fire orange instead of lime green. If it were green with black wheels and accents, a la 997.1 GT3 RS, I'd be all over it. Oh, yes, and if they would equip it with coilovers, proper brakes, a half-cage or rollbar, CF fixed shell seats, harness mounts, and strip 400-500 lbs out of the car...

Glad to see you'll be ordering the next-gen M3. Schroth has been waiting for you to sell your E90 so they can finally release the QuickFit Pros.

Last edited by paradocs98; 07-17-2012 at 10:04 PM.
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      07-18-2012, 10:15 AM   #11
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Robert, do you know if there is a min. thickness that OEM rotors need to be replaced.
vz
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      07-18-2012, 10:42 AM   #12
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[quote=paradocs98;12344365]Good info for comparison--thanks for posting. I'm on my original rotors from my StopTech ST60/ST40 BBK. They've seen 16,000 miles, about 20 track days, two sets of StopTech Street Performance pads, and have used up half of the material on a set of Pagid RS29s. Since I change my tires for the track and have access to the rotors, I decided like you to get a quality digital caliper to measure rotor thickness routinely. The fronts started at 35 mm and are now at 34.1-34.2 mm. StopTech recommends replacing them after 2 mm of wear, so at 33 mm.



QUOTE]

I changed out my 380mm Stoptech rotors well before the wear limits due to the surface cracking starting to go right to the edge.I had about 18000 kms and 20 days on them.I only used Pagid RS 14 & 29's with these rotors on track.Cheap insurance to change the rotors before you get full blown cracking issues.
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      07-18-2012, 10:58 AM   #13
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A fellow Instructors Corvette Z06 Rotors after Watkins Glen



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      07-18-2012, 11:10 AM   #14
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A fellow Instructors Corvette Z06 Rotors after Watkins Glen



that would scare the crap out of me and another example of drilled rotors cracking at/through the drill point.
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      07-18-2012, 11:14 AM   #15
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that would scare the crap out of me and another example of drilled rotors cracking at/through the drill point.
And non-floating !
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      07-18-2012, 11:24 AM   #16
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Quote:
Originally Posted by von_zoom View Post
Robert, do you know if there is a min. thickness that OEM rotors need to be replaced.
vz
It says 28.4mm on the rotor hat. I believe all rotors need to have this printed on the hat/hub. I am not sure what the BMW recommended window is, but I had mine switched at 19K and 40K.
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      07-18-2012, 11:32 AM   #17
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[QUOTEA fellow Instructors Corvette Z06 Rotors after Watkins Glen
][/quote]

At Watkins Glen , lets just say he played lucky

Quote:
It says 28.4mm on the rotor hat.
Thanks. I will have mine checked on Friday when my car is teched. I am at NASA this week end at VIR.

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      07-18-2012, 11:54 AM   #18
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Quote:
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[QUOTEA fellow Instructors Corvette Z06 Rotors after Watkins Glen
]
At Watkins Glen , lets just say he played lucky



Thanks. I will have mine checked on Friday when my car is teched. I am at NASA this week end at VIR.

vz[/quote]

He was alerted by thumping under braking so he checked them when he came in.

Here are his other rotors from an earlier day which are full floaters.

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      07-18-2012, 01:37 PM   #19
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Wow - Does he have a death wish - lives on the edge. I am sure the spider webs were visible prior to cracks, and should have alerted him of things to come, probably sooner than later.
Thanks for posting the photos. A lesson for all.
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      07-18-2012, 02:11 PM   #20
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Wow - Does he have a death wish - lives on the edge. I am sure the spider webs were visible prior to cracks, and should have alerted him of things to come, probably sooner than later.
Thanks for posting the photos. A lesson for all.
vz
My spider webs were about the same as those so changing rotors before the Glen was not an option for myself!I could just start to feel them with my finger nails and I had zero brake pulsation to that point!
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      07-19-2012, 01:15 PM   #21
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So in my 10+ year BMW club racing career, I replaced a lot of brake pads and rotors.

I'd experience about 0.001" - 0.002" of wear on the front rotors, depending on the track.

I usually ended up replacing rotors well before their wear limits as they would develop surface cracks that would catch a fingernail (highly calibrated instrument). Once a surface crack that large was detected, the rotors came off and were tossed into the scrap pile.

I never ran drilled rotors.

Now that I have retired from racing, I have more money to spend on the daily driver/track car (E46M3). I put on PFC direct drive rotors all around and they are ridiculously good (both in runout and durability). Expensive? Yes. Worth it? Yes, in my opinion.

The E90 M3 has one track day on it and less than 7k miles, so I'm not too worried about the rotors yet. Once the warranty period rotors are gone, then PFC direct drive rotors will be put on.
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      07-20-2012, 11:48 AM   #22
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Interesting.

That's why I think a Stoptech BBK can save money over the long run. The friction discs cost about the same as an OEM rotor but the discs AND pads last so much longer.

I'd estimate about 50% longer based on the wear rate on my E46. 16 track days, 1 set of PF01s, 31.65mm of 32mm on both front rotors.
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