Back to the drawing board, BBK?

[roastbeef]

Yea, I understand what you're saying.

I can tell you this- turn 8-9 is a very large, high speed, right hand sweeper. And when dogbone is trying to go faster by applying the throttle, the car is applying the drivers side front brake to influence understeer to discourage the start of oversteer.
Makes total sense... the car has enough grip to turn in, so it guards against too much turn in by activating the drivers front caliper to cause a little understeer.

[bigjae1976]

I think this is easy, get a 4 wheel BBK. I've seen people run front only and they go through rear brakes pretty fast.

Get the Stoptech ST40 FR and RR kit. The 380mm/6pot costs more, restricts you to 19" wheels and some 18s.

With an ST40 kit on all 4 corners, you can swap pads FR to RR. No need to bring spare pads!

The PFCs and AP racing kits are better, cost more and get you more man cred...but I don't see the need. Stoptechs are reliable and keep the running costs down.

[roastbeef]

i like the idea of a front to rear pad swap. thats slick.

[Solo_M_Tech]

I don't understand why everyone runs to a BBK after tracking the car with shit pads and fluid, MDM on, etc.

Get real pads, real fluid, and turn the DSC off. I've never found my stock braking set up insufficient in any track situation. ( 2 plus years of tracking this car) My current set up is this;

OEM rotors
GLOC R16 pads, front and rear
Castrol SRF fluid
bronze guides
titanium heat shields

I've thrashed these brakes for hours and hours on track. 30+ minute sessions and i've never had fade, wobble, or pulsation issues. Zero. This set up with my 275 square RS4's bring my cars speed down hard. Hard enough that track corner workers have pictures of my rotors glowing red on hard stops and the brakes never faded. Even on brake heavy tracks like the FIRM.

The E9X M3 is a heavy pig and using anything other than dedicated track pads and fluid on track, is ignorant and dangerous. just my .02

[Raindoh]

Like I said, I used a "track pad", Castrol SRF fluid and I went over the limit on the rotors. They are now warped, not every track is the same maybe the tracks you go to allow enough time for the brakes to cool in between corners.

[bigjae1976]

Originally Posted by Fubar_M3

I don't understand why everyone runs to a BBK after tracking the car with shit pads and fluid, MDM on, etc.

Get real pads, real fluid, and turn the DSC off. I've never found my stock braking set up insufficient in any track situation. ( 2 plus years of tracking this car) My current set up is this;

OEM rotors
GLOC R16 pads, front and rear
Castrol SRF fluid
bronze guides.

I've thrashed these brakes for hours and hours on track. 30+ minute sessions and i've never had fade, wobble, or pulsation issues. Zero. This set up with my 275 square RS4's bring my cars speed down hard. Hard enough that track corner workers have pictures of my rotors glowing red on hard stops and the brakes never faded. Even on brake heavy tracks like the FIRM.

The E9X M3 is a heavy pig and using anything other than dedicated track pads and fluid on track, is ignorant and dangerous. just my .02

Agreed. But going through a set of PF01 pads in 3 days on stock brakes isn't acceptable. With my stoptechs, pads last 4-6 weekends which is about on par with my E46 M3 at 3000lbs.

What that tells me is the stock brakes are getting beyond the temp limits of track pads. A good clue is your dust boot bursting into flames after a cool down lap.

Short term...a BBK can save $$$ pretty quickly. I would say it takes 10-12 events.

[Solo_M_Tech]

Originally Posted by bigjae1976

Agreed. But going through a set of PF01 pads in 3 days on stock brakes isn't acceptable. With my stoptechs, pads last 4-6 weekends which is about on par with my E46 M3 at 3000lbs.

What that tells me is the stock brakes are getting beyond the temp limits of track pads. A good clue is your dust boot bursting into flames after a cool down lap.

Short term...a BBK can save $$$ pretty quickly. I would say it takes 10-12 events.

I agree with the notion that we need thicker rotors to handle the heat. More mass to absorb and expel. BBK does this well and helps the pads live longer for sure. I ate up a set of GLOC r8 compound pads in 2 days so I know what you mean.

I'd still say for the majority of people, pads, fluid and ducting is sufficient.

I'm currently working on a ducting solution that works with my deansbimmer front tray.

[bigjae1976]

Originally Posted by Fubar_M3

I agree with the notion that we need thicker rotors to handle the heat. More mass to absorb and expel. BBK does this well and helps the pads live longer for sure.

I'd still say for the majority of people, pads, fluid and ducting is sufficient.

I can agree.

[wyatth]

My fronts brakes are shot. Stock'ish would suffice but I am thinking about a front BBK because I miss that pedal feel and confidence from the Brembo GTs on my E46.

This is the first time I've read that front-only BBK is not wise and that people then go through rears. Conversely, I've read a lot that rear BBKs are the real waste.

[Visceral]

Rear BBK is a total waste unless the looks are that important to the owner (which is OK, but the only reason).

I run a front BBK and stock rear and I go through pads in the front *slightly* faster than the rear, but not much different.

[Visceral]

Originally Posted by Fubar_M3

I don't understand why everyone runs to a BBK after tracking the car with shit pads and fluid, MDM on, etc.

With stock calipers and rotors, SRF, Ferodo 2500 F&R, steel lines, etc, I went through a set of fronts in two track days of 5 20-min sessions each. The rotors were also slightly warped after the 2nd day. Three or four times towards the end of each day the brakes would cease to function well at the end of fast straights. I'm lucky to have "gone off" on those straights multiple times, so my life didnt flash before my eyes, but it wasn't fun to barely make it.

Contrast that with the current BBK that uses F80 front rotors ($500 a pair). I went 10 events this year with a single set of Ferodo DSUno F/2500 R pads and the F80 rotors look like they've got less than a few microns of wear. Next year I'll buy another $500 in pads, $70 for another pint of SRF, and go back to riding anti-locks through my braking zones.

As mentioned, a good BBK will honestly save you money. I don't actually have an opinion on what BBK one should use as long as the F/R bias is well thought out for your tires of choice. They all have 10 minute pad changes (I swapped the F pads to 2500's after each event for the street), and they all stop you repeatedly better than stock. It's probably 95% about the thermal capacity of the bigger rotors, but I'm not sure. I just really appreciate thinking about things other than brakes during my track days.

[roastbeef]

Originally Posted by Fubar_M3

I agree with the notion that we need thicker rotors to handle the heat. More mass to absorb and expel. BBK does this well and helps the pads live longer for sure. I ate up a set of GLOC r8 compound pads in 2 days so I know what you mean.

I'd still say for the majority of people, pads, fluid and ducting is sufficient.

I'm currently working on a ducting solution that works with my deansbimmer front tray.

thickness and diameter isn't as important as efficiency. cooling vane count between the rotor faces has been proven to be the biggest factor.

at a recent laguna seca day, i was dealing with some cooked fluid because i took a set of pads down too low on my last track day and didn't realize it. i took two different guys out- one was in an e46 m3 running race pads on oem rotors, and the other guy i met at the track and got to talking. he was running race pads and fluid in his e90. both were amazed and couldn't believe the stopping power, bite, torque, and how deep in the braking zone i could go... and i was frustrated with a soft pedal from the baked fluid.

[Solo_M_Tech]

Originally Posted by roastbeef

thickness and diameter isn't as important as efficiency. cooling vane count between the rotor faces has been proven to be the biggest factor.

at a recent laguna seca day, i was dealing with some cooked fluid because i took a set of pads down too low on my last track day and didn't realize it. i took two different guys out- one was in an e46 m3 running race pads on oem rotors, and the other guy i met at the track and got to talking. he was running race pads and fluid in his e90. both were amazed and couldn't believe the stopping power, bite, torque, and how deep in the braking zone i could go... and i was frustrated with a soft pedal from the baked fluid.

I also wanna add I use titanium heat shields with all of the brake pads I use. eliminated fluid issues completely.

[bigjae1976]

Originally Posted by Fubar_M3

I'm currently working on a ducting solution that works with my deansbimmer front tray.

I also wanna add I use titanium heat shields with all of the brake pads I use. eliminated fluid issues completely.

Titanium shields help but I don't see them solving heat issues. They should prevent the dust boot from burning up and protect the pressure seal.

What's this deansbimmer tray you referenced?

[Solo_M_Tech]

Originally Posted by bigjae1976

Titanium shields help but I don't see them solving heat issues. They should prevent the dust boot from burning up and protect the pressure seal.

What's this deansbimmer tray you referenced?

The metal replacement for the felt under body panels that always break.

I need to find a way to secure the inlet for the ducting in a way that allows for sufficient airflow to the rotor.

[wyatth]

Any idea how a PFC Z54 front with OEM rears would match up (assuming matching/comparable pads F/R)? A few people run this setup but it's not that common so hoping for any feedback.

[derbo]

What about the interim solution with PFC DDv3 rotors? Anyone have experience with these and how long they last online?

[roastbeef]

Originally Posted by Fubar_M3

I need to find a way to secure the inlet for the ducting in a way that allows for sufficient airflow to the rotor.

put a naca duct on the bottom of that undertray.

https://www.pegasusautoracing.com/pr...p?Product=3628

[Richbot]

Agree ST40 front/rear is an easy button. Pad commonality, etc. is great. My STR40 front kit will soon cross 60,000 miles. The rotors are barely worn, maybe .5mm (minimum thickness is 33mm, they're 35mm thick and my 34mm max caliper still won't fit over them), the pads are about ready to be changed for something else (almost purely street driven, but gives you an idea of the system' reliability anyway).

Originally Posted by Fubar_M3

I don't understand why everyone runs to a BBK after tracking the car with shit pads and fluid, MDM on, etc.

Get real pads, real fluid, and turn the DSC off. I've never found my stock braking set up insufficient in any track situation. ( 2 plus years of tracking this car) My current set up is this;

OEM rotors
GLOC R16 pads, front and rear
Castrol SRF fluid
bronze guides
titanium heat shields

I've thrashed these brakes for hours and hours on track. 30+ minute sessions and i've never had fade, wobble, or pulsation issues. Zero. This set up with my 275 square RS4's bring my cars speed down hard. Hard enough that track corner workers have pictures of my rotors glowing red on hard stops and the brakes never faded. Even on brake heavy tracks like the FIRM.

The E9X M3 is a heavy pig and using anything other than dedicated track pads and fluid on track, is ignorant and dangerous. just my .02

There are SCCA Touring (close-to-stock prep, sortof like the old IMSA GS) racecars running stock brakes. They are also double-ducted up front and ducted in the rear, with real pads and good fluid, but, yep. If you're committed, the stock system can work just fine.

The lack of factory ducts just baffles me. y u no duct bmw, y no even air scoop? y

[bigjae1976]

Originally Posted by Richbot

The lack of factory ducts just baffles me. y u no duct bmw, y no even air scoop? y

Theory here...I think it's for aerodynamic efficiency. The air curtains on the newer gens send airflow around the wheel to reduce turbulence. Ducting brakes would mess that up. Any tech speak beyond that...I'd be MSU...making sh1t up.

Then there is no space on the front end. I'm sure BMW didn't want to put hood vents in but had to.

As I dream of building an E9X M3 track car some day...of you could move the trans cooler to the trunk and steal some airflow from the intake then maybe the lower ducts could be fashioned into brake ducts. But that's a lot of work.

[Richbot]

Even my rental E91 318d had brake ducts, but not the M3.

I'm sure they got an aero benefit from it, but come on. E46, E36, E30 all came with them. Then they were like "feh if they want brakes that work in the cold and can also stop from high speed TWICE, they can buy a GT4"

The manuals have HALF the trans cooler BLOCKED OFF from the factory.

Lazy bastards.

EDIT: Forgot my other ///Marketing theory - They were habituating us to needing to fix the brakes from the factory so they could then sell us CCB's for $10k (plus mandatory wheel upgrade!) when we traded in our leases for the next model. Joke's on them, they made this car too good and now I'm not buying another BMW haw-haw

[Mpower04]

Originally Posted by jktx

Would this setup be suitable for a full weekend at COTA for a novice? Any concern about the oem rotors holding up for 10 sessions? Have stoptech sport pads on oem rotors in good shape. If run this kit would you use pfc11 on the rear? Also have stoptech sports out back still fairly new. BBK would eventually happen - would that money be better spent making the jump now?

I use PFC V3 DD rotors front, stock rear rotors and PFC 08 pads all around on cota with no fade at all. I’m only running about 2:40 though.