BBK: how big?

[Drifty//]

I'm planning to upgrade. I'm looking at the Alcon 365mm 4-piston kit. It should fit my wheels and I think it will provide enough braking capacity. I also like that it saves a bit of unsprung mass compared to the bigger rotors and 6-piston calipers.

On a car like this, with the stock engine & exhaust, I think the main advantage of the bigger 6-piston kits is just longer pad life. But I seriously doubt I'll be running enough events to come out ahead. If I find I am chewing through pads faster than expected, I'm willing to consider brake ducting.

Does that make sense? Has anyone upgraded their brakes to a mid-sized rotor or 4-piston caliper only to find they wish they'd gone further?

[klammer]

Go big or go home

[Erhan]

This kinda depends the tracks you're running and the weather during track season. Running on 80 degree day is different than 110 degree day.

Check the pad cost & life and availability of compounds between 4 and 6 piston.
Also make sure to install good brake ducts with the BBK. The cost at that point is minimal. But the difference in performance is huge.

[Malakas]

I have the StopTech 355 kit (4 piston) front and rear. It's absolutely awesome. Never faded even doing 20+ min runs in Texas heat. Worth a look...

[Porschefile]

I've been wondering the same thing since I've thought about getting stoptechs in the near future. 380 and 355 are probably both a huge improvement over stock. I'll probably just do the fronts for awhile though, since I've heard that front only gets you 90% track performance of four wheel. Interested to hear from bbk owners.

[Martin_D]

For ST the 355mm works great.
For Brembo the 365/345 felt best...

[Martin_D]

FYI the 380 rotor is pure show on this car

[Drifty//]

Originally Posted by klammer

Go big or go home

Thanks. I was wondering how long it'd be before someone said that.

I'm glad you like your Alcons. How many track days do you get out of a set of rotors?

[FR01]

Ap racing on my fronts only. Cp5555 I think is the model (6pot 14.5"ish diameter). Pad life is good, I'm still sorting through the correct pads. Rotor life is amazing, feels hardly worn even though I've gone through 1.5 sets of pads. Bigger is better in my book however front only made sense and has worked out great so far.

[klammer]

Originally Posted by Drifty//

Thanks. I was wondering how long it'd be before someone said that.

I'm glad you like your Alcons. How many track days do you get out of a set of rotors?

I love them, holding up great. Got about 20+ track days before I had to replace the rotors and am actually at the track right now. I consistently find myself able to out brake many smaller, lighter cars that should kill me in the braking zone. Get about 5-7 days out of the carob techs pads I've been running which are about 1/2 the cost of the pagids. Great setup with over 30 track days on it thus far

[LiM3y]

When you posted a couple of weeks ago that you had your first HPDE...was it your first in your M3, or your first ever? I am trying to gauge your experience. If you are just starting out, braided steel lines, race brake fluid and track pads are a good start and will save you $5-6K of unnecessary mods. There are a lot of experienced drivers posting here that use the stock brakes with minor upgrades without issue.

[AMPowerJ]

Originally Posted by Malakas

I have the StopTech 355 kit (4 piston) front and rear. It's absolutely awesome. Never faded even doing 20+ min runs in Texas heat. Worth a look...

This is what I run. It is the trophy kit but I doubt that makes much difference. I am running Pagid 29/19 pads. Works great. These pads do sound like a bus on the street though.

[FormulaMMM]

Originally Posted by Drifty//

Does that make sense? Has anyone upgraded their brakes to a mid-sized rotor or 4-piston caliper only to find they wish they'd gone further?

I threw on Stoptech ST-40 fronts (4 piston) with Pagid RS-29 pads this year. Stock rear brakes with Cool Carbon pads. My regular tracks are quite hard on brakes. I've not even come close to exceeding the limitations of this setup.. It is incredible.

I've never heard anyone wish they had 6 piston instead of 4 because the 4 is insufficient for them on a performance level.

If I'm not mistaken, believe that Turner Motorsport uses the 4 piston Stoptechs on their M3's in the Rolex series.

[Drifty//]

Originally Posted by LiM3y

When you posted a couple of weeks ago that you had your first HPDE...was it your first in your M3, or your first ever?

If you count my A4, I've done about a half dozen 2-day events. I've solo'd once.

If you are just starting out, braided steel lines, race brake fluid and track pads are a good start and will save you $5-6K of unnecessary mods. There are a lot of experienced drivers posting here that use the stock brakes with minor upgrades without issue.

I appreciate that. I had Alcon 328 mm vented rotors w/ 4-pot calipers in my A4 and it was good (once I found the right pads!).

I just want to be able to run any track (I see VIR in my future) without fear of boiling the fluid. I know a bit about braking technique, but I want the flexibility of being able to brake late & hard without worry. Easy pad changes are a plus (I'm comfortable with pad changes on the Alcons).

[Martin_D]

change the fluid out and you won't boil it if that is your fear

rbf600

[Drifty//]

Originally Posted by klammer

Get about 5-7 days out of the carob techs pads I've been running

Which ones?

I've done pretty well with Carbotech. On my A4, I used XP8's on the track and Bobcats on the street (same rotors).

[Porschefile]

Originally Posted by Martin_D

change the fluid out and you won't boil it if that is your fear

rbf600

+1. I run stock brakes with PFC 01's, braided lines, and titanium backing plates, and I have not gotten soft pedal or boiled the fluid, even at Barber. The problem with the stock brakes isn't really boiling fluid so much as it is the small swept surface and the inefficient rotor etc. causing shuddering under braking and poor heat dissipation, leading to overheated pads. My pads were literally smoking at Barber, looked like the were going to catch fire, and PFC's don't normally do that. Even in that situation the fluid was fine.

Good to hear that many like the 355 front kits, that will save me a few bucks in the future most likely. Does 355/355 feel balanced still? I was worried that if I did 355/355 it would be more rearward biased than it should be.

[klammer]

Originally Posted by Drifty//

Which ones?

I've done pretty well with Carbotech. On my A4, I used XP8's on the track and Bobcats on the street (same rotors).

Am running xp12 up front and xp10's rear.

[von_zoom]

Originally Posted by LiM3y

If you are just starting out, braided steel lines, race brake fluid and track pads are a good start and will save you $5-6K of unnecessary mods. There are a lot of experienced drivers posting here that use the stock brakes with minor upgrades without issue.

This is exactly my set up, and knock wood, I have yet to have any problems, and PFC 01 pads provide very good lasting results.
vz

[radiantm3]

Originally Posted by Martin_D

FYI the 380 rotor is pure show on this car

Are you saying they don't have any better stopping power over stock? Because that's what "pure show" would mean.

[r53s65e90]

Originally Posted by radiantm3

Are you saying they don't have any better stopping power over stock? Because that's what "pure show" would mean.

Stoptech has very good data (piston diameters) on their website to verify the following:
1) Stopping power for 380 kit vs 355 kit is virtually the same. Both stop with the same force as the stock brakes (single 60mm piston). This is how they can claim to provide a balanced upgrade even if you go with just front BBK.
2) 380 Stoptech kit has better thermal characteristics due to the larger pads and rotors.

Don't know if brembos have higher stopping power vs stock or 380 vs 365 but I doubt it.

[radiantm3]

Originally Posted by r53s65e90

Stoptech has very good data (piston diameters) on their website to verify the following:
1) Stopping power for 380 kit vs 355 kit is virtually the same. Both stop with the same force as the stock brakes (single 60mm piston). This is how they can claim to provide a balanced upgrade even if you go with just front BBK.
2) 380 Stoptech kit has better thermal characteristics due to the larger pads and rotors.

Don't know if brembos have higher stopping power vs stock or 380 vs 365 but I doubt it.

I can attest to that. I guess I just worded my previous comment wrong. I meant braking performance in general and that means at the track as that's the only place where aftermarket brakes will become useful. My stock brakes stopped just as well as my brembo 380 kit. The difference is I can run 25 minute sessions throughout the day in 100+ degree weather without a hint of brake fade.

My biggest fear at the track is having the brakes not working properly when slowing from 125mph to 30 around a hairpin turn with a wall straight ahead. Going from the 365 to 380 kit is just a tiny fraction of the cost of the whole kit so why not get the one that will most likely stand up to heat the best. At least that's my thinking.