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      08-28-2014, 10:11 AM   #1
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Stock Brakes Severe Let Down...

I was stoked for these brakes after all the raving reviews and all of these press track days that seemed, or were advertised, to have gone off without a hitch.

However, fast forward to the real world, and after ONE track day, all four rotors are completely warped and useless...and pads are destroyed.

Now, I kind of expected the pads to be gone, let's be real. BUT, rotors to be destroyed after 6 20 minute sessions?? On an $80k ///M car? Really?

My 135is with BMW Perf front rotors and little else never had one rotor issue after 5-6 track days of hard driving.

I understand track driving is going to net increased wear on your car, but I would have expected a LOT more out of these stock components. Seems BMW engineered these steel brakes to be exponentially inferior to the massively expensive CCB's...
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      08-28-2014, 11:04 AM   #2
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Quote:
Originally Posted by F82FTW View Post
I was stoked for these brakes after all the raving reviews and all of these press track days that seemed, or were advertised, to have gone off without a hitch.

However, fast forward to the real world, and after ONE track day, all four rotors are completely warped and useless...and pads are destroyed.

Now, I kind of expected the pads to be gone, let's be real. BUT, rotors to be destroyed after 6 20 minute sessions?? On an $80k ///M car? Really?

My 135is with BMW Perf front rotors and little else never had one rotor issue after 5-6 track days of hard driving.

I understand track driving is going to net increased wear on your car, but I would have expected a LOT more out of these stock components. Seems BMW engineered these steel brakes to be exponentially inferior to the massively expensive CCB's...
Your rotors are most likely not warped at all. You probably have bad pad deposit on your discs that is causing shudder.

Stock pads on the iron rotors will not handle the heat at the track and will smear uneven deposits on the rotors. Install new pads and the shudder will likely go away after 2-3 weeks of street driving.

It has been discussed in various threads, track pads will likely be needed with the iron rotors for any serious tracking.
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      08-28-2014, 11:17 AM   #3
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Here's a good article backing up what CanAutM3 said:

http://www.stoptech.com/technical-su...nd-other-myths
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      08-28-2014, 12:49 PM   #4
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Quote:
Originally Posted by CanAutM3 View Post
Your rotors are most likely not warped at all. You probably have bad pad deposit on your discs that is causing shudder.

Stock pads on the iron rotors will not handle the heat at the track and will smear uneven deposits on the rotors. Install new pads and the shudder will likely go away after 2-3 weeks of street driving.

It has been discussed in various threads, track pads will likely be needed with the iron rotors for any serious tracking.
Interesting stuff indeed, and I do appreciate the input. However nonetheless, the rotors were measured and confirmed warped, both mathematically and visually.

The brakes are just the tip of the iceberg too; I could go into a whole thread about the let downs this car has provided from one track day...but quite simply, I do not have the time.

Massive disapointment in many ways.

At least it's a really fast street car which at least looks like it could handle a racetrack...
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      08-28-2014, 01:14 PM   #5
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Quote:
Originally Posted by F82FTW View Post
Interesting stuff indeed, and I do appreciate the input. However nonetheless, the rotors were measured and confirmed warped, both mathematically and visually.
You mean they are confirmed mathematically and visually just like that stoptech article says?

Quote:
When a driver reports a vibration under hard braking, inexperienced crews, after checking for (and not finding) cracks often attribute the vibration to "warped discs". They then measure the disc thickness in various places, find significant variation and the diagnosis is cast in stone.
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      08-28-2014, 01:33 PM   #6
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That sounds just like the E92 brakes and how horrible they were for track use. I'm sorry to hear you ran into this on the F82.
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      08-28-2014, 01:35 PM   #7
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I doubt any iron disc will become unusable after such short period of time, although anything is possible, I would imagine after you replace your pads, some clean up driving hopefully will be sufficient. Best of luck.
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      08-28-2014, 01:45 PM   #8
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Aren't the rotors 2 piece floating? Seems really curious that all 4 would warp in 1 track day, especially considering how little the rear brakes contribute. Sounds more like pad material deposits.
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      08-28-2014, 02:00 PM   #9
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It has nothing to do with your rotors as others have pointed out. You used street pads at the track and exceeded their MOT resulting in severe pad material deposition on the rotors (creating the "warped" rotor measurements). This will happen on just about any street car with street pads. If you have put some PFC08 or PFC11 pads on prior to the track session, you could have partied all day without issues.
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      08-28-2014, 02:06 PM   #10
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Quote:
Originally Posted by CSBM5 View Post
It has nothing to do with your rotors as others have pointed out. You used street pads at the track and exceeded their MOT resulting in severe pad material deposition on the rotors (creating the "warped" rotor measurements). This will happen on just about any street car with street pads. If you have put some PFC08 or PFC11 pads on prior to the track session, you could have partied all day without issues.
I appreciate all the input and the Stop Tech article is very interesting and eye opening indeed. It's entirely possible my dealer is completely retarded.

Nonetheless, I'm concerned with the unavailability of any track pads at this point and also completely unsure as to the proper process for mitigating this 'deposit' problem, assuming that is indeed the issue.
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      08-28-2014, 02:11 PM   #11
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Quote:
Originally Posted by F82FTW View Post

Nonetheless, I'm concerned with the unavailability of any track pads at this point and also completely unsure as to the proper process for mitigating this 'deposit' problem, assuming that is indeed the issue.
Apparently track pads are available, check post #18: http://f80.bimmerpost.com/forums/sho....php?t=1022435

To avoid warping you need to bed-in the brakes, check stoptech site for simple procedure.
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      08-28-2014, 07:10 PM   #12
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What a great thread with various knowledgeable folks calmly repeating sound advice.

I was fairly concerned coming into this thread. Now I feel warm and fuzzy again
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      08-29-2014, 08:04 AM   #13
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smh

Although I am fairly certain this will be a good track car, it's not suppose to be a track car out of the box. It isn't a GT3. It does many things a true track car can't do. As for your brakes, I'm sure they are fine like all the others have stated.

I have friends running in the A groups using stock E90 M3 brakes for years with just track pads that don't have warped rotors.

After your track session did you keep your brake pedal depressed for an extended period of time and/or use your e-brake?
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      08-29-2014, 08:43 AM   #14
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Quote:
Originally Posted by AMPowerJ View Post
... and/or use your e-brake?
Just as a tidbit, using the e-brake should not make a difference for pad deposit on the discs because the e-brake on those cars is an independent drum/shoe setup inside the rear disc hubs.
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      08-29-2014, 08:56 AM   #15
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Quote:
Originally Posted by CanAutM3 View Post
Just as a tidbit, using the e-brake should not make a difference for pad deposit on the discs because the e-brake on those cars is an independent drum/shoe setup inside the rear disc hubs.
Yeah I know and thought about that as I typed but I still don't use mine as just a good practice.
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      08-29-2014, 09:28 AM   #16
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Quote:
Originally Posted by AMPowerJ View Post
smh

Although I am fairly certain this will be a good track car, it's not suppose to be a track car out of the box. It isn't a GT3. It does many things a true track car can't do. As for your brakes, I'm sure they are fine like all the others have stated.

I have friends running in the A groups using stock E90 M3 brakes for years with just track pads that don't have warped rotors.

After your track session did you keep your brake pedal depressed for an extended period of time and/or use your e-brake?
I'm guessing he knows better than to put the e-brake on with hot rotors.

I'm headed to the track this weekend with my new M4. I don't plan on pushing it real hard maybe run 7/10 on just 2-3 20 minute sessions. It will be a second car for me, but I'll report back if I have any problems with light track use. Stock steels and pads too for me.
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      08-29-2014, 09:28 AM   #17
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OP, are you doing a cool down lap before coming into the pits? That will help. Also, what kind of brake fluid are you running? Agree with the others that a good set of high temp brake pads will help too.
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      08-29-2014, 09:31 AM   #18
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Quote:
Originally Posted by AMPowerJ View Post
After your track session did you keep your brake pedal depressed for an extended period of time and/or use your e-brake?
This is a subtle comment, but it's important!!

If you're coming in from a track session ESPECIALLY with stock pads which are already susceptible to lining transfer, DO NOT leave your foot on the brake pedal with the car stopped, even for a second. You'll leave a big imprint of pad material on the disc which will result in vibration your next time out.

The comment about the e-brake was simply to suggest using the e-brake (lightly) to hold the car rather than sitting in the pits with your foot on the pedal. Alternatively, wheel chocks in the pits are a good idea.
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      08-29-2014, 09:38 AM   #19
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Quote:
Originally Posted by AMPowerJ View Post
Although I am fairly certain this will be a good track car, it's not suppose to be a track car out of the box. It isn't a GT3. It does many things a true track car can't do. As for your brakes, I'm sure they are fine like all the others have stated.
Another good comment.

Despite the all the track-based marketing we see, most cars are not perfectly-suited to racetrack use straight from the showroom floor. This is especially true of brakes, where manufacturers will ALWAYS prioritize [low] noise/dust/wear over outright track performance. If you read the M3 manual, the ONLY thing specifically mentioned in the track use section is that the brake pads aren't suitable for tracks. Should any of us be surprised when the stock pads don't work particularly well in this environment?

The Porsche GT3 RS may be the one exception, where the stock car is running a variation of Pagid RS19 from the factory.

It's been mentioned several times, but anyone taking the car to the track should seriously consider the BMW Performance pad kit, or one of the offerings from Pagid (RS19/RS29).
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      08-29-2014, 10:27 AM   #20
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Quote:
Originally Posted by F82FTW View Post
It's entirely possible my dealer is completely retarded.
Yeah, just going to go with this, with a caveat is not that your dealer is retarded, but they are unused to dealing with something outside the boundaries of normal. Hot pad deposit on rotors is outside the bounds of normal for everyday driving. Very few people actually track their cars, and the ones that do, usually know enough to use seperate track pads.

Anyways, as others have said, get a new set of pads on there, perhaps driving for a week or two with track pads on to remove the deposits, and then back to regular street pads.

Final comment: a set of chocks at the track is always good to have, for multiple reasons, including this one.

Final final comment: if you did, indeed, warp all four rotors from one track day (which I highly doubt), your experience is far outside the experience of others who have tracked their M4. If true, you might want to consider your braking habits as a possible culprit (not meant as an insult, just a suggestion)

Last edited by Mandi90TT; 08-29-2014 at 10:28 AM.. Reason: One more comment I forgot
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      08-29-2014, 10:59 AM   #21
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I recently had PFC race tech help me with a brake issue on my spec racecar. Here's the back and forth, pertinent info underlined. Your rotors can take the heat, the pads however couldn't. Race pads on even the stock steel rotors should put your face thru the windshield. I use PFC, sometimes Pagid. Also keep in mind if your using DSC, it's modulating your brakes and putting heat into them you may not even be feeling.

I instructed at COTA for a Ferrari event last year, the pits had a line of F cars getting their rear brakes worked on. Some drivers were using traction/stability control as a total crutch, pads were melting, fluid was cooked, smoke coming from their CCBs, horrible driving. These were 458s and piggy Californias, the older cars no problem.


Quote:
1. With the knockback, does the class allow 2-piece discs?
Only OEM cast one rotors piece allowed

2. With sealed bearings in the hubs, does the preload go away when the car comes in from the race track?
Unsure, however one bearing is starting to make noise when cornering and may need to be replaced.

3. We need to get the discs, pads painted up and the calipers stickered up so we aren’t so blind as what’s really going on here.
I've ordered ti barriers, caliper stickers and temp indicator paint to get data.

4. Brake pad Ti thermal barriers can be purchased from http://hardbrakes.com/

5. Discolored brake fluid means the caliper’s bulk temp is in excess 190c. 210c is the limit for the seals. It’s likely time to refurbish the calipers.
Planning on doing this.

-Brake fade is when the pedal is hard, but after a period of time the braking efficiency starts to diminish.
Not getting this

What brake fade is when the system gets hot enough to cause distortion or compressibility or something in the hot end of the brakes becomes thermally instable like the brake pad. (08 compound is good to 800c which is 150c higher than the iron in 1-piece OE disc) This instability causes non uniform distribution of the friction materials and the end result is a loss of brake efficiency. (In layman’s terms, the car losses stopping power for the same effort over time)


-going over center on the brake pedal and loosing mechanical advantage, effect is soft pedal and lost efficiency.

-aggressive "jump in" from the initial apply and the ABS strategy implements a "preemptive mode" and pulls pressure out of the system there by reducing "bite" in an effort to maintain threshold tire grip,

Help me understand please

There’s a 1.5hr technical seminar I do for PCA, Porsche’s Tech Tactics, SCCA National convention, Performance Racing Industry and David Murry Trackdays that covers this. We will have a video on this but it’s a huge amount of work to edit it so it’s not on line yet.

I will be in Austin for the IMSA/WEC race Sept 15-21, 2014.

Darrick Dong
Director of Motorsports
Performance Friction Brakes
ddong@performancefriction.com;
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      08-29-2014, 11:39 AM   #22
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Excellent point about people using DSC/MDM mode on the track as it makes serious use of rear brakes, individually (fronts also), and puts a huge additional load into the braking system. If you're driving at a serious and competent level, you should not need a nanny since all the nanny does is help an inexperienced driver create bad habits in addition to unneeded brake loads.

Note the #4 above. I've been using Ti shims for 10 years, and they are essential to preserving your piston dust covers and seals -- especially when the pads are worn down below 1/2 thickness, etc. The pad material is an outstanding insulator, so when its thickness is reduced as they wear, backing plate temperatures (and therefore heat transfer into the pistons) goes up proportionally.

With three simple things, I'm sure the F8x brakes will work wonderfully and provide good service life:

1) PFC/Pagid/etc race pads
2) Motul 600 or equivalent high temp DOT4 fluid
3) Ti shims

I guess the 4th item is to not drive the car near its limits for extended sessions if you're having to use stability control; if you are going to do that, I'd recommend using Ti shims in the rear also.

Cheers,
Chuck
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