F8X Brembo BBK Swap on E46 M3

[mikeetastic]

So if i need to source the set, what donor car and year im looking for? I check realoem and partnumber and found these cars with the same caliper/rotors, is the list correct?

thanks all, really not familiar with newer cars and since ill be needing pads and rotors soon on my zcp perhaps add more money and upgrade to this setup.

[Johnvu]

Any info on the brake bias? I have the E31/996 combo laying around and would like to know if this is a better solution?

I don't have exact numbers but from what I have read on M3Cutters and another member on page 3, it looks like brake bias is slightly rear biased on the 2001-2003.5 models, and near perfect for the 2003.5+ models we the updated ABS system. I am running some Ferodo DS2500 pads and all around daily and plan to switch the fronts to DS1.11 for track days. I have heard this works well and it should also help with the rear bias.

[Johnvu]

Do The rear caliper mounting points need to be machined down 2.5mm as well? Or is that only the fronts that need that?

No, only the fronts need to be machined down =).

[Cglhut]

Any info on the brake bias? I have the E31/996 combo laying around and would like to know if this is a better solution?

Check out the 3rd page in this thread, specifically post #44. All the info you need is there.

[SeanE46]

Any info on the brake bias? I have the E31/996 combo laying around and would like to know if this is a better solution?

[Cglhut]

Do The rear caliper mounting points need to be machined down 2.5mm as well? Or is that only the fronts that need that?

[tdott]

380 is too large to be beneficial for sure. Can’t run 18s, which are way better for this car on track than 19s, much less 17s. No need for the extra heat capacity over 355s.

ARC8 is the only Apex wheel that wouldn't fit (barrel wise). All others will fit on an M3/4, including the newer Forged Arc8R.

I had to sell my Arc8 track setup when I moved to f8x brakes on my e92m3.
These are BW TA5R in the common track 18x10 et25 size (after a track day)

[Johnvu]

Yeah, apex goes out of the way to make it work. My track setup is 17” apex wheels, which are the only 17s I know of that can clear 355mm BBKs... which I meant I had to compromise other things to run 17s. With 380s you’re making the same compromises in order to run 18s, with no hope of 17s.

... not to mention that the 380s are extra unsprung mass and rotational inertia without a functional benefit over 355s.

Both set ups have their own positives. If you are going for ultimate light wight in which 20 lbs is going to make a difference, then yeah it seems like the 996 swap is the way to go. However, most people won't be anywhere near that level of weight reduction.

In my opinion, the f8x swap is the most cost effective system that substantially upgrades the brakes over oem. However, I honestly dont think you can really go wrong with either of the swaps bc both are way better than factory.

[Obioban]

Apex lists several 380mm kits that fit under their 18" wheels, and 18" wheels fit over the F8X brakes on the F8X cars... between those two pieces of information, I don't think it's a reach to assume there are readily available 18s you can run.

Yeah, apex goes out of the way to make it work. My track setup is 17” apex wheels, which are the only 17s I know of that can clear 355mm BBKs... which I meant I had to compromise other things to run 17s. With 380s you’re making the same compromises in order to run 18s, with no hope of 17s.

... not to mention that the 380s are extra unsprung mass and rotational inertia without a functional benefit over 355s.

[r4dr]

380 is too large to be beneficial for sure. Can’t run 18s, which are way better for this car on track than 19s, much less 17s. No need for the extra heat capacity over 355s.

Apex lists several 380mm kits that fit under their 18" wheels, and 18" wheels fit over the F8X brakes on the F8X cars... between those two pieces of information, I don't think it's a reach to assume there are readily available 18s you can run.

[Obioban]

380 is too large to be beneficial for sure. Can’t run 18s, which are way better for this car on track than 19s, much less 17s. No need for the extra heat capacity over 355s.

[r4dr]

The paradox is that good drivers are actually easier on the brakes. No overbraking, proper technique, etc.

You only have too much brake until you don’t 🤡

[Johnvu]

I thought the 996 retrofit used OE rotor sizes. Is the issue that there aren't any quality two piece rotors available?

I'll likely go with either the F8X or the 996 calipers in the future. I think 380/370 is overkill for e46, but can never have too much brakes i guess...

I definitely agree with your last statement lol.

[clawhamm3r]

Is that based on Mk 60 brake bias?

It was later determined that MK60/20 rear pistons didn't matter in the equation...can't remember why. Something to do with proportioning valves and equal pressure, or true north and climate change..something like that. p0lar even said all of his original charts were wrong because they calculated for that and put disclaimers on his original post in *the* brake bias thread. And that one dude in another thread (maybe streamline thread?) hooked a raspberry pi up measuring outputs form both MCs and confirmed this.

Also his (p0lar) charts had a pad friction coefficient....we all collectively agreed we could ignore that because we know different compounds have different friction coefficients. If we just want to calculate straight bias based on caliper/piston/rotor sizes (which is what we love to debate on the forums), then we can ignore that as well.

Finally, he was also factoring in for leg strength lol. Once again, if we just want to focus on the parts that would be changing for our cars with everything else equal, we can drop that variable (make it a 1?) in the equations and a very different brake bias picture begins to take shape.

Enter me during the Streamline DB9 debates, all I did was gather all the latest information and plug the formulas into a Google Sheet calculator. I should have taken better notes but I didn't realize we were going to lose the forum. Let's not lose this one too, my mind is getting old and it isn't what it used to be. Anyway, technically it should be called a Caliper/Rotor Brake Torque Bias Calculator or something.

[Johnvu]

What are the piston sizes and pad dimensions? I'll update the brake bias calculator for us.

Weight vs. heat dissipation: I'd take the unsprung weight savings of a monoblock aluminum caliper all day. If you need a 380/370 you're pretty hardcore on the track side of this debate and are not doing an F8X retrofit anyway. Agree the 996 is a lot of work for a 345 and it's a shame, but the 996 retrofit to me is about handling, pedal feel, and bling. The downfall of the 996 retrofit is the non-existing rotor selection...you're stuck with fake 2pc rotors made out of butter. Okay I'll climb down now, sorry. Whoever had bad pedal feel with the 996 needs to keep bleeding lol.

Good write-up OP.

Lol yeah, I can't personally speak to the pedal feel of the 996 swap but this pedal definitely feels pretty good. I honestly won't be anywhere near the limit for these brakes or the 996 brakes at the track since im still a noob, but they sure do look fantastic behind the wheels lol. I also figured I would have enough brakes for a long time as I learn and grow on the track =).

Also thank you for calculating the brake bias! I was starting to do the calca but then got swamped with work. Could you possibly do this for both the mk60 and DSC3?? Thanks!