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      06-01-2012, 09:02 AM   #1
besiktas
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How to avoid warping stock rotors at track?

Ok, the one way to answer this is to be more conservative at track. My question is, if i have higher quality brake pads, would it prevent damaging my rotors? or regardless of the brake pads the rotors will get damaged as they dont handle heat well either?

I am thinking of investing some $$$ on higher quality brake pads but if they are still going to cause my rotors to go bad, then i might not.

Thanks
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      06-01-2012, 09:09 AM   #2
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Your rotors do not warp at the track but it is uneven pad deposits that cause the pedal pulsation.Proper track pads such as Pagid RS 29's and a proper cool down lap before entering to pits will go a long way to eliminating this problem.

http://www.stoptech.com/technical-su...nd-other-myths
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      06-01-2012, 09:11 AM   #3
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You might be suffering from uneven pad deposit (search this). It is tough to warp the stock M3 rotors, but easy to overwhelm the street pads. During press release days for the E9X M3, BMW installed ceramic pads in the stock car.

This happens to all novices transitioning to intermediate and indicates time to switch pads and brake fluid to higher spec racing fluid for track days. Braided steel lines help too.

[Gearhead beat me too this]
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      06-01-2012, 09:16 AM   #4
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Quote:
Originally Posted by Gearhead999s View Post
Your rotors do not warp at the track but it is uneven pad deposits that cause the pedal pulsation.Proper track pads such as Pagid RS 29's and a proper cool down lap before entering to pits will go a long way to eliminating this problem.

http://www.stoptech.com/technical-su...nd-other-myths
+1 ^^ This

The M3 rotors are pretty robust.

Last edited by CanAutM3; 06-01-2012 at 11:39 AM.
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      06-01-2012, 09:45 AM   #5
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Another good way to prevent the "warped" feeling is after the cool down lap, do not come to a stop and hold the brakes or engage the emergency brake in the pits. If you have to, have a piece of wood to stop the car from rolling. Holding the car with the brakes on is a great way to deposit pad material onto hot rotors.
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      06-01-2012, 10:07 AM   #6
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Also, if the session turns into an extended one (i.e. more laps than the usual), try to run a cool-down lap or two somewhere during the session.
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      06-01-2012, 04:17 PM   #7
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It is interesting all these sources tell you it is nothing more than a build up or deposit of pad material, but if you have your rotors turned to true them the lathe operator will show you the metal being removed to bring the run out down to acceptable levels. It is definately not pad material being removed, because if it was your rotor thickness would not be sustantially reduced they way it is to get a true rotor. Since I first started seriously tracking cars in 1989 using stock rotors and race pads I have found that every car since then (Mazda RX2 race car, Acura Integra R, C5 Corvette, Mitsubishi Evo 8, C6 Z06, and now the M3) all will produce a warped rotor after 4 to 6 one day track events, assuming you are pushing hard enough to get a lot of heat into the braking system. In my opinion rotors are consumable items when tracking your M3 just like the pads, brake fluid, and tires are.
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      06-01-2012, 04:18 PM   #8
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Quote:
Originally Posted by Gearhead999s View Post
Your rotors do not warp at the track but it is uneven pad deposits that cause the pedal pulsation.Proper track pads such as Pagid RS 29's and a proper cool down lap before entering to pits will go a long way to eliminating this problem.

http://www.stoptech.com/technical-su...nd-other-myths
^This..warping rotors is not as common as most people think..most of time fault lies with the pads
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      06-01-2012, 05:48 PM   #9
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Quote:
Originally Posted by Bbenavitz View Post
It is interesting all these sources tell you it is nothing more than a build up or deposit of pad material, but if you have your rotors turned to true them the lathe operator will show you the metal being removed to bring the run out down to acceptable levels. It is definately not pad material being removed, because if it was your rotor thickness would not be sustantially reduced they way it is to get a true rotor. Since I first started seriously tracking cars in 1989 using stock rotors and race pads I have found that every car since then (Mazda RX2 race car, Acura Integra R, C5 Corvette, Mitsubishi Evo 8, C6 Z06, and now the M3) all will produce a warped rotor after 4 to 6 one day track events, assuming you are pushing hard enough to get a lot of heat into the braking system. In my opinion rotors are consumable items when tracking your M3 just like the pads, brake fluid, and tires are.
I use to have issues with cementite when using heavy metallic pads but never with the newer type pads. and when you try to cut them with a brake lathe the bit will start to chatter and will not cut properly and then the best solution is to replace the disc.90 % of the time rebedding the brakes will clean up the pad deposits.On my previous E92 M3 ran 3 years with about 40 track days on the original standard rotors with no issues.

[quote]The only fix for extensive uneven deposits involves dismounting the discs and having them Blanchard ground - not expensive, but inconvenient at best. A newly ground disc will require the same sort of bedding in process as a new disc. The trouble with this procedure is that if the grinding does not remove all of the cementite inclusions, as the disc wears the hard cementite will stand proud of the relatively soft disc and the thermal spiral starts over again. Unfortunately, the cementite is invisible to the naked eye./QUOTE]
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      06-04-2012, 08:24 PM   #10
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Great link, thanks.

Quote:
Originally Posted by Gearhead999s View Post
Your rotors do not warp at the track but it is uneven pad deposits that cause the pedal pulsation.Proper track pads such as Pagid RS 29's and a proper cool down lap before entering to pits will go a long way to eliminating this problem.

http://www.stoptech.com/technical-su...nd-other-myths
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      06-04-2012, 10:06 PM   #11
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Quote:
Originally Posted by Bbenavitz View Post
It is interesting all these sources tell you it is nothing more than a build up or deposit of pad material, but if you have your rotors turned to true them the lathe operator will show you the metal being removed to bring the run out down to acceptable levels. It is definately not pad material being removed, because if it was your rotor thickness would not be sustantially reduced they way it is to get a true rotor. Since I first started seriously tracking cars in 1989 using stock rotors and race pads I have found that every car since then (Mazda RX2 race car, Acura Integra R, C5 Corvette, Mitsubishi Evo 8, C6 Z06, and now the M3) all will produce a warped rotor after 4 to 6 one day track events, assuming you are pushing hard enough to get a lot of heat into the braking system. In my opinion rotors are consumable items when tracking your M3 just like the pads, brake fluid, and tires are.
Funny... I did not warp one rotor in 6 years of driving schools and 10+ years of racing (and instructing) and I had terrible technique for a number of years -- way too late and way too hard -- great way to build up heat. Add in that for many years the car was a two driver car and you have the recipe for warped rotors. All brakes were stock but the pads were not, they were always race pads. Started with PF90s, used Hawk HT-14 and HT10s, PF01s, and now since I'm retired I run PF06's. PF08's will go on the car next. For the street I use PFC Z-rated pads so there is no need for bedding between the different pads as I swap them. Plug and play. No. I don't work for PFC nor do I have a financial interest in anyone who sells PFC pads (wish I did).

Stock pads on the track will produce pad deposits as I found out at the Salzburgring in 2002 with a new M3. Switched to Hawk pads since I had three more tracks to run (A-1 ring, both tracks at the Nurburgring) and no problems. Those in the group that didn't switch rotors, including some uber fast racers (National champion w/years of ring experience is one example) did have pad deposits even when being careful.

A great way to remove stock pad deposits is to put on a set of aggressive race pads and do some street driving with them. That'll machine a bit off the rotors in no time!

OP: Get some good track pads for your DE events and enjoy your car.
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      06-05-2012, 02:10 PM   #12
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I don't track my E92 M3 anymore (got an E36 racecar), but never had a problem with rotors. OEM rotors are actually pretty darned good quality already. Occasional judder can be from deposits, as others have noted.

Your pads are more likely to fail under track stresses than your rotors. Pads can melt, split, suddenly chunk, and before you know it you have stopping problems and a 4-figure maintenance repair.

Hawk DTC-70s are awesome pads for our heavy beasts, and they are very kind to the rotors and sustain high heat extremely well. (And you can keep them on the car throughout the season, as long as you don't mind the dying cat sound as you approach every stop on the street. Or swap them just for track weekends.) If the 70s aren't doing it, next step would be a BBK kit to get more volume to absorb all that friction heat. That's what I'd do if I were tracking more than the occasional DE weekend.
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      06-05-2012, 02:15 PM   #13
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Hawk DTC-70's paired with the factory rotors along with decent fluid and SS lines are a great combination.

I have managed to warp the two front rotors on the E9x M3 at the track. It was 95* out and after about 7 sessions on stock pads. A little bit of machining on the lathe took care of it and they were as good as new again with plenty of rotor thickness remaining.
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