Stock Brakes Severe Let Down...

[gthal]

Originally Posted by F82FTW

Seems to be an increasingly common standpoint...bummer.

I've been looking into Carbotech's offerings for F8x brake pads, and they have A LOT! However they require you to machine your rotors prior to install and also do not recommend drilled rotors for track use period.

Anyone know of slotted discs being available for F8x yet?

That's not what I was told... and I didn't need to do that on my C7 either when I went to Carbotech pads. I was told that if I hadn't been to the track yet and mileage was relatively low on the car, I could use their track pads right away. They do recommend their street pads after that to ensure compatibility of compounds.

Also, drilled rotors are generally more prone to cracking so many will suggest slotted as a better option. However, unless you are tracking very heavily, there shouldn't be an issue in my experience.

[gthal]

Originally Posted by Floridagator

This thread is frustrating to me. Why is anyone surprised that the stock brakes don't work very well at the racetrack? NO pad will work well in every environment. This is a road car first, so BMW obviously prioritized (low) noise/dust/wear over track performance (as does every major manufacturer). BMW is aware of the brake limitations on the racetrack, which is exactly why they:

1) Put specific language in the manual indicating the pads should be changed before track use and
2) Developed a specific track-capable friction material available through the BMW Performance catalog

I also suspect the same people voicing their disappointment about the track performance would be the first ones to complain if the brakes were squealing.

At least with the F80 we have a good set of base hardware to work with (aluminum fixed calipers, composite discs). We weren't so lucky with the previous-generation cars.

Bottom line, if you want to go to the track, spend $500 on track pads, burnish them properly, you should be fine for some laps at 8/10ths. And if you want drive more than 8/10ths, you may want to consider racing rather than HPDE events.

Just my $0.02

Agreed... other than for a new, novice driver, pretty much any OEM brake system will need some tweaking. It is just part of the deal with tracking a car. Pads and fluid are a bare minimum for almost anyone taking the car out.

The good news is BMW made it easy to swap pads with the F8X... which was less so the case with the E9X... so it's an hour of work before a track day and an hour after to swap the track pads in and out.

[dapopa9]

Originally Posted by F82FTW

I was at Buttonwillow where I have a fair amount of experience. FWIW, I ran a 2:02.705 with a bone stock car...apparently this is pretty damn fast.

That's a great time for a stock car at BW!! That's quite a few seconds faster than most stock E90 M3 were running.

[Dalko43]

Originally Posted by CanAutM3

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.

How the hell would you know if this guy's rotors were/were not warped....short of you being there in person to offer your opinion, I don't see how you can make that kind of assessment.

[CanAutM3]

Originally Posted by Dalko43

How the hell would you know if this guy's rotors were/were not warped....short of you being there in person to offer your opinion, I don't see how you can make that kind of assessment.

Common sense, experience and general engineering knowledge.

Iron rotors of the size offered on the F8X are are very robust and therefore extremely unlikely to warp. However, as posted multiple times in this thread, pad deposit is very often confounded with warped rotors, even by "professional shops". See the very good article in the Stoptech webpage referenced in post #3.

Note that I did use the words "most likely" though, so I did not present it as an absolute .

[pkimM3r]

Originally Posted by gthal

Agreed... other than for a new, novice driver, pretty much any OEM brake system will need some tweaking. It is just part of the deal with tracking a car. Pads and fluid are a bare minimum for almost anyone taking the car out.

The good news is BMW made it easy to swap pads with the F8X... which was less so the case with the E9X... so it's an hour of work before a track day and an hour after to swap the track pads in and out.

hour? takes me 20-30. 5-7 minutes on each side. taking the wheel off is harder than swapping the pads lol. sometimes in lazy and swap pads at the track and have had to swap out done pads between sessions. never doing it again at buttonwillow in the sun though. but I'll do it in a garage at a track anytime.

if the f80 brakes are of the push the pin out and slide the pad out type holy that would be fast as heck!

[CanAutM3]

Originally Posted by hgmotorsports

Most people have already stated the obvious.

1) Leaving traction control/stability control on can lead to uneven brake wear
2) After a hot track session, if you leave your foot on the brake or put the ebrake on while sitting you can warp rotors
3) Street pads can leave blotches of pad around the rotor if heat up to a significant temperature
4) Your rotors should not be warped after such a short use and having already been bedded in from the factory. If you had new disks and were experiencing this problem I would assumed the bedding in procedure was not sufficient or not followed correctly.

A few correction (IMHO):

1) ...not uneven brake wear, but rather put more stress on the brake system (read more heat) which can lead to more uneven pad deposit and premature fade.

2) ...applying hot brakes while car is stationary or moving slowly will not warp the rotors but rather put a "blotch" of pad material (to use your wording ) on the disc leading to uneven pad deposit on the disc

... applying the e-brake will not have any impact because the e-brake on the F8X is a separate drum/shoe setup inside the disc hub (as it was on the E46 and E9X).

[PrimeBMW]

Originally Posted by Dalko43

How the hell would you know if this guy's rotors were/were not warped....short of you being there in person to offer your opinion, I don't see how you can make that kind of assessment.

Nobody knows for sure but: It is common knowledge that BMW replaced many rotors they thought were warped. I believe this was a mistake as most of us that have driven hard on the back roads or at the track with OEM street pads will get some significant vibrations/surging under braking. Slap in some race pads and that all goes away. The cold race pad will scrape the oem pad material off. No warp just oem pad deposits.

[evanescent03]

Originally Posted by CanAutM3

A few correction (IMHO):

1) ...not uneven brake wear, but rather put more stress on the brake system (read more heat) which can lead to more uneven pad deposit and premature fade.

2) ...applying hot brakes while car is stationary or moving slowly will not warp the rotors but rather put a "blotch" of pad material (to use your wording ) on the disc leading to uneven pad deposit on the disc

... applying the e-brake will not have any impact because the e-brake on the F8X is a separate drum/shoe setup inside the disc hub (as it was on the E46 and E9X).

i think i pretty much agree with you but i'm wondering what your stance on warped rotors is… do you think it's possible? i know i've read stories of guys actually cracking/breaking the rotor after coming in from a session (granted i think those were corvette stories, but similar principles apply), don't you think the uneven cooling could warp 'em in extreme cases? it just seems like you think warping is impossible, so i'm just curious.

anyway, i've dealt with pad deposit issues several times with e46 M3 and Hawk HP Plus pads, really frustrating because i was convinced i did the bed-in process correctly and everything. hopefully i don't have similar issues with the F80 … that shudder is like nails on a chalk board!

[CanAutM3]

Originally Posted by evanescent03

i think i pretty much agree with you but i'm wondering what your stance on warped rotors is… do you think it's possible? i know i've read stories of guys actually cracking/breaking the rotor after coming in from a session (granted i think those were corvette stories, but similar principles apply), don't you think the uneven cooling could warp 'em in extreme cases? it just seems like you think warping is impossible, so i'm just curious.

anyway, i've dealt with pad deposit issues several times with e46 M3 and Hawk HP Plus pads, really frustrating because i was convinced i did the bed-in process correctly and everything. hopefully i don't have similar issues with the F80 … that shudder is like nails on a chalk board!

Everyone can have different experience, but I have tracked an E46 for 7 years and an E92 for 6 years at a rate of 12~20 track days per season. I have never encountered warped rotors. Further, reading on the topic, it is quite unlikely that rotors as robust as the ones found on those cars would warp. I have also used Hawk HP+ pads extensively. While they are a reasonable el' cheapo alternative, they are far from being the best track pad and do require quite a bit of management to avoid pad deposit. Since I have switched to PF08, there is no more issues with pad deposit. The PF08 also have a much better initial bite than the HP+ and last longer, so from a cost perspective it is a wash.

As far as cracked rotors go, yes two of my track buddies with Corvette's crack their rotors 2 to 3 times per season. On the other hand, I have yet to crack a single rotor in 180+ track days with both my ///M cars. With drilled rotors, you will see some cracking around the crossdrill holes. This is normal, but need to monitor those cracks. If cracks reach from one hole to another or even worse a crack reaches to the outer edge of the disc, then it is time to replace the disc. So far I always have needed to replace my rotors due to wear and not cracks though.

[evanescent03]

Originally Posted by CanAutM3

Everyone can have different experience, but I have tracked an E46 for 7 years and an E92 for 6 years at a rate of 12~20 track days per season. I have never encountered warped rotors. Further, reading on the topic, it is quite unlikely that rotors as robust as the ones found on those cars would warp. I have also used Hawk HP+ pads extensively. While they are a reasonable el' cheapo alternative, they are far from being the best track pad and do require quite a bit of management to avoid pad deposit. Since I have switched to PF08, there is no more issues with pad deposit. The PF08 also have a much better initial bite than the HP+ and last longer, so from a cost perspective it is a wash.

As far as cracked rotors go, yes two of my track buddies with Corvette's crack their rotors 2 to 3 times per season. On the other hand, I have yet to crack a single rotor in 180+ track days with both my ///M cars. With drilled rotors, you will see some cracking around the crossdrill holes. This is normal, but need to monitor those cracks. If cracks reach from one hole to another or even worse a crack reaches to the outer edge of the disc, then it is time to replace the disc. So far I always have needed to replace my rotors due to wear and not cracks though.

good explanation, thanks! i'll definitely be looking at different pads this time around. some tracks i didn't have much of an issue with the HP+ but other tracks i noticed a lot of pad deposit.

i haven't used drilled rotors before, but am aware of the small cracks turning into larger cracks so that's something i'll be monitoring. thanks again!

[stonecliff]

Originally Posted by CanAutM3

Everyone can have different experience, but I have tracked an E46 for 7 years and an E92 for 6 years at a rate of 12~20 track days per season. I have never encountered warped rotors. Further, reading on the topic, it is quite unlikely that rotors as robust as the ones found on those cars would warp. I have also used Hawk HP+ pads extensively. While they are a reasonable el' cheapo alternative, they are far from being the best track pad and do require quite a bit of management to avoid pad deposit. Since I have switched to PF08, there is no more issues with pad deposit. The PF08 also have a much better initial bite than the HP+ and last longer, so from a cost perspective it is a wash.

As far as cracked rotors go, yes two of my track buddies with Corvette's crack their rotors 2 to 3 times per season. On the other hand, I have yet to crack a single rotor in 180+ track days with both my ///M cars. With drilled rotors, you will see some cracking around the crossdrill holes. This is normal, but need to monitor those cracks. If cracks reach from one hole to another or even worse a crack reaches to the outer edge of the disc, then it is time to replace the disc. So far I always have needed to replace my rotors due to wear and not cracks though.

+1. Similar experience here with E36s and E46s. Never had a warped rotor as proper bedding would always take care of any brake judder, but it is possible for the micro cracks to turn into a full crack. Was a little surprised as I had also never had a rotor previously crack, but a good reminder to take 2 minutes to look them over periodically, including between sessions on a track day.

If only there was a PFC fitment for the F82!

[jbraslins]

Just fyi, I got a new set of rotors and put carbotechs on them. Did not do any crazy bedding in, just drove to track and then on it. No issues what so ever.

I think Pagid RSL1s are just finicky about proper bedding and left ton of deposits on the rotors.

[dmk08]

Originally Posted by jbraslins

Just fyi, I got a new set of rotors and put carbotechs on them. Did not do any crazy bedding in, just drove to track and then on it. No issues what so ever.

I think Pagid RSL1s are just finicky about proper bedding and left ton of deposits on the rotors.

Did you have to buy the rotors?

[thebishman]

Originally Posted by jbraslins

Just fyi, I got a new set of rotors and put carbotechs on them. Did not do any crazy bedding in, just drove to track and then on it. No issues what so ever.

I think Pagid RSL1s are just finicky about proper bedding and left ton of deposits on the rotors.

It is absolutely crucial that you bed in the rotors and new pads and this is nowhere more important than on a road course. There is nothing worse than trying to decelerate at the end of a decent straight and the car doesn't slow down because the pads haven't been seasoned. You just had best hope there's decent run-off.
Bish

[jbraslins]

Originally Posted by thebishman

It is absolutely crucial that you bed in the rotors and new pads and this is nowhere more important than on a road course. There is nothing worse than trying to decelerate at the end of a decent straight and the car doesn't slow down because the pads haven't been seasoned. You just had best hope there's decent run-off.
Bish

I am not racing, I don't need 100% performance on lap 1 turn 1. For anyone doing your usual DE (novice or advanced), the first lap of the day that's usually under yellow anyway is enough to get them bedded in, with plenty of buffer for anticipating emergencies. At least that's what everyone I know does, including people racing spec e30 with NASA.

Not saying bedding them in per instructions is a waste. I just think it's unnecessary for the avg. joe.

I base my experience on many sets of PFCs 08s and now a set of Carbotechs that I've used over the years.

Perhaps it's critical for Pagids, first time I ever had rotor issues after just one session.

[jbraslins]

P.S. Most bedding-in instructions suggest several consecutive hard stops from 90mph+ to 30, with as quick acceleration back to 90 between them as possible.

I am yet to find a place where you can do that safely. It's definitely not on the street or highway. Most tracks don't allow this kind of stuff in the paddock or surrounding areas either.

So even if you were bedding them in, you'd be doing it on track during practice. Which is basically what regular DE is

And, if during DE or practice, officials saw a car speeding up to 90 than braking hard to 30, for no reason other than to bed-in pads, I am sure it would get black flagged.

[stonecliff]

Originally Posted by jbraslins

Just fyi, I got a new set of rotors and put carbotechs on them. Did not do any crazy bedding in, just drove to track and then on it. No issues what so ever.

I think Pagid RSL1s are just finicky about proper bedding and left ton of deposits on the rotors.

Did you use any tools to spread the pads in the caliper, or was it easy enough to do by squeezing by hand? Want to make sure I don't scratch the paint on the caliper...

[jbraslins]

Originally Posted by stonecliff

Did you use any tools to spread the pads in the caliper, or was it easy enough to do by squeezing by hand?

Just pressed really hard on the pads (one thumb on top of the pad, one at the bottom)

[Sapper_M3]

Originally Posted by jbraslins

Just pressed really hard on the pads (one thumb on top of the pad, one at the bottom)

This.

But you gotta use your man-hands. If that should fail (pshh, it's never happened to me), a c-clamp of the right size would do the trick.

[MaynardZed]

Originally Posted by Sapper_M3

This.

But you gotta use your man-hands. If that should fail (pshh, it's never happened to me), a c-clamp of the right size would do the trick.

No C clamp on the F8x because it's a monoblock caliper that stays on while changing the pads. Just press firmly with the old pad in place on those metal tab things. If that doesn't work you can use a big flat head and press carefully on the piston(s) itself prying against he rotors.

[Sapper_M3]

Originally Posted by MaynardZed

No C clamp on the F8x because it's a monoblock caliper that stays on while changing the pads. Just press firmly with the old pad in place on those metal tab things. If that doesn't work you can use a big flat head and press carefully on the piston(s) itself prying against he rotors.

Augh, my bad! I didn't mean to put out bad info.

Thanks for the assist!