Thoughts on (new?) 4 piston Brembo retrofit BBK

[M3MPH1S]

I saw this 4 piston Brembo retrofit BBK in another thread that I've never seen before and wanted to hear y'alls thoughts on the idea of using this as a cost-conscious setup with a small performance gain.

https://freakyparts.co.uk/collection...-big-brake-kit

Without any pads the kit is £600, plus shipping to the US is about £50, so that comes out to about $850 shipped. You can also add Ferodo, Carbotech, and Pagid pads for extra money but it seems cheaper to source those domestically.

What I'm wondering is how well this will perform compared to the stock calipers. I'm guessing better, but I was thinking if it's 4 tiny pistons vs our 1 massive piston it might be the same/worse. It looks like it might save some weight too. Of course the biggest advantage is that since it fits OEM rotors, I can buy them through FCP Euro and replace them for free (minus return shipping cost).


Edit: Adding/consolidating some preface information

Reason for consideration of this kit is because I have almost 150k miles on the OEM calipers/pistons. I currently use Pagid RS19 pads and haven't had any issues with fade or not enough braking power, but have had issues with mushy pedal feel for the first 1/4 to 1/3 of the brake pedal travel. I already have SS lines (front/mid/rear) and using Castrol SRF, and bleeding/flushing doesn't seem to help.

[roastbeef]

Don't do it.

[M3MPH1S]

Originally Posted by roastbeef

Don't do it.

Any particular reason?

[dparm]

Originally Posted by M3MPH1S

I saw this 4 piston Brembo retrofit BBK in another thread that I've never seen before and wanted to hear y'alls thoughts on the idea of using this as a cost-conscious setup with a small performance gain.

https://freakyparts.co.uk/collection...-big-brake-kit

Without any pads the kit is £600, plus shipping to the US is about £50, so that comes out to about $850 shipped. You can also add Ferodo, Carbotech, and Pagid pads for extra money but it seems cheaper to source those domestically.

What I'm wondering is how well this will perform compared to the stock calipers. I'm guessing better, but I was thinking if it's 4 tiny pistons vs our 1 massive piston it might be the same/worse. It looks like it might save some weight too. Of course the biggest advantage is that since it fits OEM rotors, I can buy them through FCP Euro and replace them for free (minus return shipping cost).

There is a huge thread about another company that does the same thing: Brembo caliper retrofits on E92 brake rotors. I suggest reading through it, there's been extensive debate on how much of an upgrade this is for sustained hard use.

The setup is fine for improving aesthetics and street driving, but I would never use it on the track.

[M3MPH1S]

Gotcha, I'll search some more

[dparm]

So I don't want to make it sound like I don't care about answering your question and "LOL OMG search noob".


My biggest issue with this setup is that it eschews the notion of a braking SYSTEM. Everything must be designed to work together. By shoehorning a completely different caliper onto the OEM rotor, you have effectively discarded all of the R&D that BMW, BMW's brake supplier, and Brembo have done.

Okay, so now you have a more rigid caliper. What about the rest of the system? Can it keep up? Have you just introduced stress onto something else that was unanticipated? You still have the OEM rotors which aren't that good at cooling. You are also limited to this specific caliper's pad size and selection. Several of the BBK benefits (cheaper consumables, better cooling, bigger pad selection, thicker pads, etc.) are missed in the name of saving a few bucks.


I would also say that this sentence just screams red flag:

"The kit has been thoroughly tested by many owners in many different applications from normal road to track use."

Tested how? What were the results? Who was doing the test? What were the reasons for the test? Do you think they would really post back if someone had a caliper fail at 140mph on the track? Simply installing them and not crashing is not a test of the braking system. And anecdotal posts of "well I've had it for a year and no problems" tells us nothing other the fact that it bolts up. Brakes are a safety item and this sort of cavalier attitude is ridiculous.


On the topic of money, you could find a decent used StopTech ST40 kit for about $1500, maybe less. Sure, it doesn't have the bling of the Brembo name, but it's a proven kit that was designed specifically for the E92. You get true two-piece rotors that are beefy and can last a long time, which means lower running costs. These rotors also have immensely better cooling than the OEM units. The caliper itself allows you to run a relatively inexpensive pad shape that opens the door to a lot of compound changes and again, reduced consumable costs. Plus you get stainless lines in the kit.

Walk through the pits at a track day and look around. No one is running a retrofitted Brembo caliper.

[M3MPH1S]

Originally Posted by dparm

So I don't want to make it sound like I don't care about answering your question and "LOL OMG search noob".


My biggest issue with this setup is that it eschews the notion of a braking SYSTEM. Everything must be designed to work together. By shoehorning a completely different caliper onto the OEM rotor, you have effectively discarded all of the R&D that BMW, BMW's brake supplier, and Brembo have done.

Okay, so now you have a more rigid caliper. What about the rest of the system? Can it keep up? Have you just introduced stress onto something else that was unanticipated? You still have the OEM rotors which aren't that good at cooling. You are also limited to this specific caliper's pad size and selection. Several of the BBK benefits (cheaper consumables, better cooling, bigger pad selection, thicker pads, etc.) are missed in the name of saving a few bucks.


I would also say that this sentence just screams red flag:

"The kit has been thoroughly tested by many owners in many different applications from normal road to track use."

Tested how? What were the results? Who was doing the test? What were the reasons for the test? Do you think they would really post back if someone had a caliper fail at 140mph on the track? Simply installing them and not crashing is not a test of the braking system. And anecdotal posts of "well I've had it for a year and no problems" tells us nothing other the fact that it bolts up. Brakes are a safety item and this sort of cavalier attitude is ridiculous.


On the topic of money, you could find a decent used StopTech ST40 kit for about $1500, maybe less. Sure, it doesn't have the bling of the Brembo name, but it's a proven kit that was designed specifically for the E92. You get true two-piece rotors that are beefy and can last a long time, which means lower running costs. These rotors also have immensely better cooling than the OEM units. The caliper itself allows you to run a relatively inexpensive pad shape that opens the door to a lot of compound changes and again, reduced consumable costs. Plus you get stainless lines in the kit.

Walk through the pits at a track day and look around. No one is running a retrofitted Brembo caliper.

Haha don't worry, I didn't take the response like that. Thanks for writing out your opinion though. The ST40 kit is what I've really been eyeing for a while now (both used and new) and just saw this one and started thinking. I don't care about brand name (especially Brembo - never been a huge fan), I just want something that works decently.

I kinda figured this might be the case, but was still trying to be optimistic. I'll just wait and save up for a proper brake kit like I've been doing

[dparm]

M3MPH1S, just curious, what attracts you to this kit other than the low cost of entry versus a full BBK?

Why do you feel you need this upgrade? Are you trying to resolve a perceived deficiency in the OEM setup? What is the intended use? What leads you to believe this will be an effective upgrade?

I'm all for a productive discussion to share knowledge on braking systems in the interest of helping you find something that will work. We've discussed it before but sometimes these discussions get lost in the shuffle of us bullshitting.

[dparm]

Originally Posted by M3MPH1S

and started thinking. I don't care about brand name (especially Brembo - never been a huge fan), I just want something that works decently.

Why aren't you a fan of Brembo? Yeah, they definitely get a lot of OEM contracts, but that's just one part of their business. I know everyone has a raging boner for AP Racing (who Brembo owns, BTW), but look on race cars and you'll see plenty of Brembo setups. They have a good product.

http://www.brembo.com/en/company/new...-brembo-brakes

[M3MPH1S]

Originally Posted by dparm

M3MPH1S, just curious, what attracts you to this kit other than the low cost of entry versus a full BBK?

Why do you feel you need this upgrade? Are you trying to resolve a perceived deficiency in the OEM setup? What is the intended use? What leads you to believe this will be an effective upgrade?

I'm all for a productive discussion to share knowledge on braking systems in the interest of helping you find something that will work. We've discussed it before but sometimes these discussions get lost in the shuffle of us bullshitting.

Honestly, I've been quite satisfied with the OEM setup + Pagid RS29 pads up until recently when I've started having issues with mushy pedal feel for about the first 1/4 to 1/3 of the pedal travel. I already installed SS lines and I've tried re-bleeding fluid (Castrol SRF), but it still doesn't really help. After the pads actually engage, the brakes still work fantastically.

The other part of my situation is that I've got 148k miles on the car and there doesn't seem to be a large sample size as to what parts will start to go out, especially with extra abuse from the track. It's probably mostly in my head, but still have to wonder. And I am also due for front rotors soon. So those 2 things combined had me re-looking into buying some type of BBK sooner rather than later. I was thinking that maybe by replacing the calipers with fresh ones (even if the 4 piston Brembo was the same performance as OEM) that I might fix my pedal issue. And of course for the rotors, now would be a good time to switch to a BBK since I need new ones anyway, so whether it was OEM/Brembo or Stoptech, anyway wanted to make a decision.

[dparm]

Originally Posted by M3MPH1S

Honestly, I've been quite satisfied with the OEM setup + Pagid RS29 pads up until recently when I've started having issues with mushy pedal feel for about the first 1/4 to 1/3 of the pedal travel. I already installed SS lines and I've tried re-bleeding fluid (Castrol SRF), but it still doesn't really help. After the pads actually engage, the brakes still work fantastically.

Sounds like you are seeing the deficiencies in the OEM fixed caliper, and the so-so cooling. Even a basic BBK will feel a hundred times better.

Also, RS29 is an endurance pad. Are you able to keep enough heat in those things for a 20-30 minute HPDE session? Are you running R-comps or scrubs? Have you ever measured your caliper and rotor temps?

[M3MPH1S]

Originally Posted by dparm

Why aren't you a fan of Brembo? Yeah, they definitely get a lot of OEM contracts, but that's just one part of their business. I know everyone has a raging boner for AP Racing (who Brembo owns, BTW), but look on race cars and you'll see plenty of Brembo setups. They have a good product.

Yeah, no doubt they make good race setups. I know the GT-R kits are some of the best as far as steel brakes go. I've just always been slightly turned off because it seemed there was a "brand name" tax. And seeing kits like this just makes me think show off, not performance

[M3MPH1S]

Originally Posted by dparm

Sounds like you are seeing the deficiencies in the OEM fixed caliper, and the so-so cooling. Even a basic BBK will feel a hundred times better.

Also, RS29 is an endurance pad. Are you able to keep enough heat in those things for a 20-30 minute HPDE session? Are you running R-comps or scrubs? Have you ever measured your caliper and rotor temps?

I've never measured temps, but I seem to be able to keep sufficient heat. I do always have to do some excessive prep braking on the first lap out though. I'm just running 200tw currently (ZIII). Tire temp and similarly caliper/rotor temp is on my shortlist of things to start monitoring.

[dparm]

Originally Posted by M3MPH1S

Yeah, no doubt they make good race setups. I know the GT-R kits are some of the best as far as steel brakes go. I've just always been slightly turned off because it seemed there was a "brand name" tax. And seeing kits like this just makes me think show off, not performance

The GT-R setup is nice, but is still somewhat targeted at street use. Too blingy for my tastes.

Look at their Club Race setups. Those are legitimate race car brakes. Not cheap, but they ditch the showy paint jobs and other street-focused features in the name of maximum performance. You can also get those bridge cooling and disc pressurization setups.

http://www.rogueengineering.com/Brem...ems_c_242.html

(the E92 front kit is about $7k)

Originally Posted by M3MPH1S

I've never measured temps, but I seem to be able to keep sufficient heat. I do always have to do some excessive prep braking on the first lap out though. I'm just running 200tw currently (ZIII). Tire temp and similarly caliper/rotor temp is on my shortlist of things to start monitoring.

If you haven't measured temps, how do you know you're keeping sufficient heat in them?

I have to wonder if you've got too much pad in there. Buy a set of the temperature decals and get the thermographic paint for the rotors. This would also help you see if you're boiling the fluid.

[M3MPH1S]

Originally Posted by dparm

If you haven't measured temps, how do you know you're keeping sufficient heat in them?

I have to wonder if you've got too much pad in there. Buy a set of the temperature decals and get the thermographic paint for the rotors. This would also help you see if you're boiling the fluid.

Haha fair enough, you caught me. Just been using my butt dyno. I'll check out the decals. I'm due for front pads as well. Anything you'd recommend I try instead? I was looking at Ferodo or Carbotech potentially, or I could always go with one of Pagid's more aggressive offerings.

[dparm]

Originally Posted by M3MPH1S

Haha fair enough, you caught me. Just been using my butt dyno. I'll check out the decals. I'm due for front pads as well. Anything you'd recommend I try instead? I was looking at Ferodo or Carbotech potentially, or I could always go with one of Pagid's more aggressive offerings.

I would call Dave at Zeckhausen Racing and ask his advice. Tell him I referred you. He's very knowledgeable and will want to discuss your driving style, tracks you go to, etc. to help pick a pad. He knows BMWs pretty well.

https://www.zeckhausen.com/

I wonder if he'll suggest DTC-60s.

[roastbeef]

all these retrofits are garbage because they do nothing to address the weakest link of the oem braking system- the rotors.
you could pair these calipers with aftermarket rotors and frankenstein together a kit, but its still going to be mediocre at best. people pretend these "kits" are better, but they are in denial because they already purchased them.
you might get misaligned pads, misaligned caliper pistons on the pads, calipers that rub the rotor (somehow).
someone was nice enough to post a video review.

read the essex blog on essexparts.com about what makes a great brake kit. even if you don't use their brakes, it is educational and you can compare from there.

[roastbeef]

if you're not willing to wait a little longer and budget for a better bbk, spend the money on quality fluid, stainless lines, maybe some shims, and run some ducting. all that can be done for the same approximate $700.

[M3MPH1S]

Originally Posted by roastbeef

if you're not willing to wait a little longer and budget for a better bbk, spend the money on quality fluid, stainless lines, maybe some shims, and run some ducting. all that can be done for the same approximate $700.

Yeah I've already got SS lines (front, rear, mid) and I've been running Castrol SRF, considering trying out something else though (maybe RBF 600). I wasn't aware of shims until y'all were talking about them the other day but I'm interested. So we'll see.

[dparm]

Originally Posted by M3MPH1S

Yeah I've already got SS lines (front, rear, mid) and I've been running Castrol SRF, considering trying out something else though (maybe RBF 600). I wasn't aware of shims until y'all were talking about them the other day but I'm interested. So we'll see.

Stick with SRF unless you want to bleed and flush the fluid constantly. The whole point of SRF is that you put it in and leave it alone for a while.

[roastbeef]

Yea, SRF is the good stuff. Shims might help, but I'd start keeping an eye out for a slightly used bbk.
Are you fading the brakes, or just looking for more?

[M3MPH1S]

Originally Posted by roastbeef

Yea, SRF is the good stuff. Shims might help, but I'd start keeping an eye out for a slightly used bbk.
Are you fading the brakes, or just looking for more?

Nah, just looking for potential improvements. Not having any issues with performance currently aside from mushy pedal for the first 1/4 to 1/3 of pedal travel. Brake bleed/flush not helping. Wondering if the piston/calipers might be the issue since I'm nearing 150k. I did buy some new plastic caliper bolt sleeves so maybe that will help. And I'm also due for new front rotors pretty soon, so all of it came together as a good potential opportunity.