[Bimma360]

Edit: Started a new thread on the topic, see here: https://x3.xbimmers.com/forums/showthread.php?t=2072977

A few on the forum have ventured into the 6 Piston caliper upgrade from the X5M (and a few other models). The good news is that they fit. Unfortunately, I haven't read much discussion (sorry if I missed it) about how brake bias, if at all, is affected. Much of the focus seems to be on the increase of brake pad surface area, and although that has its own merits, it has no influence on brake bias.

I already had a calculation spreadsheet I put together for the E36 and figured I add the X3M to it as I was pretty curious.

The following are the calculations I came up with. Take note of the values, as they may need to be updated. Since this is a relatively new chassis, information was difficult to come by. For example, the Master Cylinder Bore (MC Ø) is taken from other M models of this era and is a best guess, same with rear caliper piston diameter. If anyone has definitive information on some of these variable, I'll update the calculations. However, whatever the values may be they do remain constant as the caliper is the only thing that is changed here. Speaking of the caliper, I only calculate the piston area of one side of an individual caliper. Multiplying that by 2 yields the piston area of the whole caliper, and multiplying again by 2 yields the total piston area for the entire axel (front or rear). It really doesn't matter though for the bias calculation as long as you are consistent front and rear. I figured I mention this as it can cause some confusion.

**Take note, that these bias %'s are not meant to be real world accurate, but instead a comparison to the calculated factory bias as certain variables are changed (rotor size, caliper piston size, etc). In other words, the goal is to see how and to what extent certain rotor, caliper, and/or brake pad changes made deviate from the calculated factory number.

This is the calculator used:


Static Brake Bias Calculator
https://brakepower.com/brake-bias-static.htm
Calculator for Automotive and Racing Brake Systems, Master Cylinders, Brake Bias, Piston Area, CG Height, Weight Transfer, etc.

A note about "Effective Radius of Brake Rotors," which can cause some confusion:

"The effective radius of a brake rotor is measured from center of brake pad to center of brake rotor. In other words, it is the distance from rotor-center to halfway the swept area of the rotor.

More accurately but less easy to measure: it's the distance from rotor-center-line to center line of caliper piston(s)."



So it turns out that these particular 6 piston calipers actually have a smaller total piston area than the stock 4 piston calipers, by about 5%. Since all other variables remain the same, there is no way around it, using these calipers will surely shift the brake bias toward the rear. For now it looks like its is about a 2.4% reduction in front Bias. This number can move up or down if I am wrong about the stock piston sizes front and rear, or if I am wrong about the pad heights.

You'll also see that there is another calculation showing what happens to the bias if we change the CoF of the pads. I saw that the iSweep brands publishes a chart that shows their pads' approximate CoF, as I wanted to pull a real world example of how we can account for this rear brake bias shift by using different pads front and rear. In that particular example, it looks like you can actually increase the front bias vs stock by about the same %.

HOWEVER, in a totally separate matter I stumbled onto something interesting. The iSweep chart shows the factory BMW X3M pad CoF at about 0.38.



But it looks like the factory Brembo pads for both the X5M and X3M are GG rated.

"The friction performance of pads intended for typical street temperatures is classified under SAE Standard J866, expressed as a two-letter code where the first letter designates the normal low-temperature (200 to 400 degrees F) friction performance, and the second letter the high-temperature (300-to-650 degrees F) friction performance."

The G code corresponds to a CoF of 0.45-0.55. A GG pad is pretty aggressive. For a street only car that won't see temps past 650F, empirically you can't do better. I don't want to throw any shade towards iSweep, as I know most love their pads, but I question under what circumstances they got the stock pad CoF to show under 0.4. Those would be FF pads, and I am more inclined to trust the GG rating from an OE manufacturer (Brembo). For fun, take the OE black line in the chart above and move it up to where the 572F dot aligns with 0.45.

Anyway, now that I probably derailed my own thread right from the first post. Here we are.

[strohw]

Your Excel sheet shows that the 4 piston and 6 piston brake setups use the exact same pad size. Is that actually the case?

[Bimma360]

Originally Posted by strohw

Your Excel sheet shows that the 4 piston and 6 piston brake setups use the exact same pad size. Is that actually the case?

It’s not pad size, but pad height. Based on a picture from another thread both pad heights appear to be about 90mm. This also makes sense if you think about it. As both the X3M and the X5M use the same rotors, so the pad height should be same.

[strohw]

Originally Posted by Bimma360

It’s not pad size, but pad height. Based on a picture from another thread both pad heights appear to be about 90mm. This also makes sense if you think about it. As both the X3M and the X5M use the same rotors, so the pad height should be same.

Thanks. I misread your header for the column and I didn't think they used the same pad shape. But I agree that it seems logical that they are the same pad height. Also, it's pretty common for 6 piston setups to have less clamping force compared to 4 piston setups for the same fixed setup. At least the bias is going in the safer direction for most people, creating additional understeer.

[BlownLSX]

Originally Posted by Bimma360

It’s not pad size, but pad height. Based on a picture from another thread both pad heights appear to be about 90mm. This also makes sense if you think about it. As both the X3M and the X5M use the same rotors, so the pad height should be same.

To bad we can’t make m5/m8 brakes work.

[Bimma360]

Originally Posted by strohw

Thanks. I misread your header for the column and I didn't think they used the same pad shape. But I agree that it seems logical that they are the same pad height. Also, it's pretty common for 6 piston setups to have less clamping force compared to 4 piston setups for the same fixed setup. At least the bias is going in the safer direction for most people, creating additional understeer.

No worries. The BMB64 calipers found in some Maseratis and AMG's would be a lot better as their piston sizes are 30/34/38mm with a an area of 2748mm^2. But I can't recall if they can be used with a rotor up to 395mm. Those may require custom brackets to work though if so, most likely.

Onto the safety point, the internet census (for what its worth) seems to be that for a street car a small bias increase toward the front is preferred and for a track car a small bias increase toward the rear is acceptable.

A bias increase toward the rear will cause the rear to now lock up sooner relative to the front compared to stock. I wouldn't want that, especially on the street in the rain. Now yes, we do have ABS and what this would mean is that the ABS will activate in the rear sooner. But then again, the ABS system was design under the factory brake bias. If it were me I would feel more comfortable with a bias increase toward the front, albeit I am not sure how I feel about a 2.4% increase in either direction honestly.

Originally Posted by BlownLSX

To bad we can’t make m5/m8 brakes work.

I don't know much about this but if the front rotor fits, with custom brackets (if needed) I don't see why not. If we have any info on these, I can add it to the spreadsheet to see where we stand.

Edit: It looks like the M5/M8 calipers and rotors are the same size as the ones I noted above in the chart.

[TacosRule!]

If you read the posts by Kevin The Clean 1 and BulkBen

here

https://x3.xbimmers.com/forums/showthread.php?t=1999560

and here

https://x3.xbimmers.com/forums/showthread.php?t=1858189

You'll see that the M5 calipers do fit, the issue is getting the M5 OE brackets since they dont ship with the calipers. However, tro-ink sells said brackets, and they're pricey.

https://tro-nik.com/product/bmw-x3-g01-x4-g02_gold/

Doing my research for the past month came to find out that the M5 CCB brakes *do not* fit our cars, they're physically taller to accommodate a larger carbon ceramic rotor, which also includes getting larger dust shields and so forth. So you're forced to get the entire CCB kit

https://tro-nik.com/product/x4m-g02-...big-brake-kit/

Yep, its that expensive. Plus in my experience tro-nik has very bad customer service, hardly reply to messages and availability is very sketchy. It has been done though

https://inf.news/en/auto/b14e175b8f4...ff392fd2e.html

So in my mind, it's faster easier and cheaper to stay with the F95/F96 brakes since they're a direct swap.

Also in those threads you'll see that the brake lines get stretched something link half inch, so it's not a big deal. However in the interest of safety margin I am planning on getting new brake lines to mitigate this.

EDIT: the posters from the above threads I mentioned have said there is zero impact to brake bias.

[Bimma360]

I totally read those posts. But there is certainly an impact on brake bias. That’s not debatable. That impact, whether or not is negligible, can be debated.

[TacosRule!]

Originally Posted by Bimma360

I totally read those posts. But there is certainly an impact on brake bias. That’s not debatable. That impact, whether or not is negligible, can be debated.

Measure it and then share your results, interested to see what you find

[Bimma360]

Originally Posted by TacosRule!

Measure it and then share your results, interested to see what you find

Haha what? It’s all in the first post dude.

Also, I meant to add regarding carbon ceramics. Even if fitment wasn’t an issue, you can’t just run CCB’s on the front only. That’s insane (sorry if I misunderstood your intent). And with these modern cars, even if CCB’s were a factory option for your specific model you still need to update coding in order to retrofit. So it’s not just a bolt on affair. From a coding perspective I don’t even know what that would mean for the X3M when CCB’s weren’t even an option. Haha

[Max Well]

Originally Posted by Bimma360

A few on the forum have ventured into the 6 Piston caliper upgrade from the X5M (and a few other models). The good news is that they fit. Unfortunately, I haven't read much discussion (sorry if I missed it) about how brake bias, if at all, is affected. Much of the focus seems to be on the increase of brake pad surface area, and although that has its own merits, it has no influence on brake bias.

I already had a calculation spreadsheet I put together for the E36 and figured I add the X3M to it as I was pretty curious.

The following are the calculations I came up with. ...

HOWEVER, in a totally separate matter I stumbled onto something interesting. The iSweep chart shows the factory BMW X3M pad CoF at about 0.38. ...

But it looks like the factory Brembo pads for both the X5M and X3M are GG rated. ...

The G code corresponds to a CoF of 0.45-0.55. A GG pad is pretty aggressive. For a street only car that won't see temps past 650F, empirically you can't do better. I don't want to throw any shade towards iSweep, as I know most love their pads, but I question under what circumstances they got the stock pad CoF to show under 0.4. Those would be FF pads, and I am more inclined to trust the GG rating from an OE manufacturer (Brembo). For fun, take the OE black line in the chart above and move it up to where the 572F dot aligns with 0.45. ...

Appreciate the deep dive you did into this subject, Bimma360 and for sharing your thought process so we can follow along. Your suggestion to move the OE black line to more mirror the iS2000 would be in line with what r33_RGSport indicated was his favorite after testing them and bringing to market.

Personally, we chose the iS1500 as the wheel dust was the main focus for us - as I have no issues braking at the Strip with them I'm fine with their performance, but if I were to require more track-focused characteristics my mindset would change.

Thanks again for sharing.

[Kevin_The_Clean1]

Originally Posted by Bimma360

A few on the forum have ventured into the 6 Piston caliper upgrade from the X5M (and a few other models). The good news is that they fit. Unfortunately, I haven't read much discussion (sorry if I missed it) about how brake bias, if at all, is affected. Much of the focus seems to be on the increase of brake pad surface area, and although that has its own merits, it has no influence on brake bias...

I just read your entire thread. But still tying to figure out what exactly you're trying. attempting to say or prove here. Yes, the much larger calipers have a MUCH WIDER overall pad width which increases the total pad volume about 80%+. So instead of standing on the brake pedal with the 4-piston units, you can gently nudge & apply the brake pedal & achieve much quicker / substantial shorter stopping distance with the stout mono-block 6-piston calipers.

Shifting the brake bias reward 2.4% is relatively negligible IMO. Wouldn't this actually be an improvement, especially on X3 M's that have been properly lowered... ? (IE: Far less over brake dive) Again, especially those X3 M's that have been properly modified with the wider tires & this 265/40 FRONT & 295/35 REAR rubber upgrade... (wouldn't this allow better braking front to rear)... ? (IE: wider contact patch on rear + 2.4% rear bias increase = win win for all dynamic handling characteristics)... ?

I've created 2 great threads on this very same subject (see below) that have gotten pretty good traction. So I appreciate your calculations & still wondering how we can benefit from this new information. Are you saying the much better 6-piston front calipers upsets the braking balance of the F97 X3 M buy 2.4% rearward & therefore should not be done... ?

Originally Posted by BlownLSX

Too bad we can’t make m5/m8 brakes work.

Too bad you didn't do all your homework on this or a touch more research. You do realize... the M2 / M3 / M4 / M5 / M8 / X5M / X6M ALL USE THE SAME FRONT 6-PISTON BREMBO OEM BRAKES right... ?

So those that have completed this easy front caliper upgrade (like I have) DO HAVE THE SAME STOPPING POWER as the M5 & M8. Feel free to read my thread on this very same subject.



https://x3.xbimmers.com/forums/showthread.php?t=1999560

https://x3.xbimmers.com/forums/showthread.php?t=1796142

[Kevin_The_Clean1]

Originally Posted by Bimma360

I totally read those posts. But there is certainly an impact on brake bias. That’s not debatable. That impact, whether or not is negligible, can be debated.

Now I'm starting to catch on to your drift. As someone who has done this "highly worthy" upgrade with lots if success & has extensive seat time after performing this easy bolt on swap, I can wholeheartedly say this is extremely negligible. And saying that would be a substantial understatement. The first X3 M owner to ever perform this lives in Australia I believe & he had lots of dedicated track time in his X3 M. So much so he was designing custom brake ducts to further his track experience. While I appreciate you bringing this up, the overall affect on driving dynamics can't really be perceived. In other words, 2.4% may seem like a lot on paper, but on the street, road & track, this is nothing. Just my .02 cents.

[Bimma360]

Originally Posted by Kevin_The_Clean1

Yes, the much larger calipers have a MUCH WIDER overall pad width which increases the total pad volume about 80%+. So instead of standing on the brake pedal with the 4-piston units, you can gently nudge & apply the brake pedal & achieve much quicker / substantial shorter stopping distance with the stout mono-block 6-piston calipers.

Well, I suppose this is probably the best place to start.

(1) A larger pad will absorb more heat, which will take longer to overheat. It will also have a larger contact area with the rotor allowing for a better path to pull the heat out of the pad and dissipate it into the air. Allllllll this means is that the 6 piston pads will take a lot more abuse without fading. It does NOT mean you decrease your stopping distance. That's not how this works. And both the 4 and 6 piston pads have the same CoF, so again... not decreasing your stopping distance.

(2) When you decrease the total piston area of a caliper, you are now pushing less fluid through that caliper. That results in reduced brake pedal travel. THAT is what you are describing as "gently nudge." But again, this will NOT decrease your stopping distance. That's not how this works.

"quicker / substantial shorter stopping distance" - That is preposterous.

(3) I started this thread b/c I have already ran through this exercise before many times, was curious, and decided it was worth sharing here. Because, this mod does indeed take your braking system out of factory calibration.

I do see that you "caught my drift" but based on your reply I will tell you what my point is here. Frankly, thinking that a bigger pad and 6 pistons equates to a substantial decrease in stopping distance, hell any decrease in stopping distance, is just amateur hour. Sorry, but it's true.

I wouldn't call this mod "highly worthy." The ONLY gain with this mod is reducing brake fade under repeated abuse. For someone that takes their X3M to the track (not the drag strip), I would say that this is probably worthwhile. And if you are someone that tends to cook their stock pads on the street, sure. But for just about all other street cars this is a giant waste of money, and not much of an upgrade. In fact all you are doing is skewing your factory brake bias, for a gain you will actually rarely experience. Is a 2.4% reduction in front bias negligible? Maybe. But I would hate to find out at 70mph+ in the rain on the highway.

[Kevin_The_Clean1]

Originally Posted by Bimma360

I wouldn't call this mod "highly worthy." The ONLY gain with this mod is reducing brake fade under repeated abuse. For someone that takes their X3M to the track (not the drag strip), I would say that this is probably worthwhile. And if you are someone that tends to cook their stock pads on the street, sure. But for just about all other street cars this is a giant waste of money, and not much of an upgrade. In fact all you are doing is skewing your factory brake bias, for a gain you will actually rarely experience. Is a 2.4% reduction in front bias negligible? Maybe. But I would hate to find out at 70mph+ in the rain on the highway.

I greatly appreciate your knowledge here & input on this subject matter. My X3 MC is not a daily driver by any means. When it's driven on the street, most of the time it's after hours, when there's little (if any) other people out on the roads. So even when my F97 is not on the track / road course, much more often than not, it sees speeds that most other people aren't even remotely comfortable with, regardless of what vehicle they're sitting in and/or driving.

When I need shave off tons of speed before overcooking & entering the next corner a touch too hot, I would have to begin applying the brakes a whole lot sooner & stand on the pedal quite a bit longer with much more force (with the stock 4-piston calipers). Now (with the much more stout & robust 6-piston calipers) I can now brake much later for a much shorter period of time & I don't have to stand on the pedal with equal amounts of force. The X3 MC now stops with much more composure, authority & a lot less fuss. In other words, threshold braking is performed in much more abrupt yet stabile manner. A lot (less brake dive too overall) because that weight transfer is done for a much shorter period of time.

For the type of aggressive driving I typically do on my (non-daily driver) regardless of road surfaces, this 2.4% is very VERY negligible. So again, although this may be a concern for you on paper with your calculator, it doesn't translate to "much if any" of this (affecting the front to rear bias balance as you said) in the real world. And to say "But for just about all other street cars this is a giant waste of money, and not much of an upgrade... " could not be any farther from the truth in my book. If you want red coal hot little mini bricket pads stopping your 600-700+ HP X3 MC at above triple digits speeds "which is easy for a machine that runs mid 11's bone stock" that's your business. But I would like a true mono-block 6-piston caliper designed to handle tons more heat & repeated abuse. (see the actual photos of these 4-piston VS 6-piston brake pad sizes being mentioned here below, not just calculations)

I know you say theres no decrease in stopping distances with this upgrade. AND, you also think this isn't really considered an upgrade at all & a WASTE OF MONEY, just like you said too. And although I respect your realistic fact based opinions & statements, I occasionally have to call people's bluff on a few things. I would love to hook up some official test equipment for more official data measurements & get both the 4-piston stock calipers & the X5 M 6-piston calipers at peak operating temps, then do a few 120 MPH to zero stops, lets say 3 back to back for good measure. Then begin testing the stopping point differences between these two setups & at that time I'm confident there's a good chance you would have to begin eating crow.

Again, the speeds that I often do (only on the streets of Mexico of course) & on a big open road course are both scenarios the stock calipers simply can't handle well for very long. If you like to having a lot more fun than your average X3 MC owner typically does, then there's a very good chance you're experiencing brake fade. Whether you know it or not / whether you're aware of it or not & you being able to perceive that or not is surely debatable. But... when I'm slowing X3 MC down from 120-140 MPH on a fairly routine basis, the 6-piston brakes DO MAKE A SUBSTANTIAL DIFFERENCE & ARE NOT A WASTE OF MONEY. Maybe to you in your head this is true & on paper you don't see the calculations panning out. For those that daily drive their X3 M's & never get but a touch over the speed limit, then yes, those F97's won't see much of a value add here. But the moment they begin pushing the stock brakes on their X3 M's harder & harder, the 4-piston calipers with the small pads will show / reach their limitations much quicker.

If these factory 6-piston front brake calipers that BREMBO built to BMW's specs weren't considered an upgrade by any means (JUST LIKE YOU SAID) then why are they standard equipment on the M2 / M3 / M4 / M5 / M8 / X5M / X6M... ? And why are these built onto BMW cars that are much heavier & more powerful then the X3 M, if these weren't a better designed caliper all-together... ? I do see some of your reasoning. But saying this is a waste, not really considered an upgrade & technically won't help your ride stop in a shorter amount of distance once at full operating temps... seems a little far fetched. Don't you think... ?

[95wildtt]

I think you are both correct, and there really is no need to throw stones at each other over this topic...
I did the same upgrade (to X5M Calipers) on my 4.8 E70 several years ago, and while I felt it made a big difference, and mostly looked really cool, it was a great upgrade in my mind and well worth the $$s I spent.

Not sure why BMW opted for the smaller 4 pot calipers instead of the 6 pot for the F9X.
Maybe they felt we would be less likely to use our SUVs to the maximum, or because they were saving money, who knows why...??
On the M2/3/4 they are typically used on the track more often, I would assume.
On the M5/XxM they are heavier and higher HP cars, that also hit a higher price point so they can spend the extra $$s.

Simply, the numbers don't lie, and common sense will tell you the brake bias will change slightly... the key here is the word slightly.
I seriously doubt any of us are capable of telling the difference through our butt dyno and we probably aren't trained to push the F9X to 100% anyway.
So, for the way all of us use our F9x, we'll be fine... Very interesting to note the numbers though.

The reason for the larger pad area (on any car) is to better dissipate heat from high speed and/or repeated stops, like those described or on the track.
In order to create the same maximum pressure on the rotor/brake surface more pistons are needed, as the force is spread over a larger area.
The limit for the pressure on any setup is the adhesion of the tires, once traction is lost it doesn't matter what brakes you have...

To dissipate the heat absorbed by the larger pads, and then through the additional pistons and fluid, a larger caliper is also needed to dissipate that heat into the air, and ultimately cool the brakes.
So, the larger setup is affecting the bias, but very slightly, and what it does do for very spirited driving is keep the brakes much closer to 100% at all times so you don't get the fade associated with the smaller surface areas.

Do some research on the internet, lots of opinions, and lots of science

Botton line is, if you want to upgrade, do it... there are lots of benefits for YOU and your F9x, and that's all that really matters, right?

[Edgar_FriendlyX3M]

Aside from aesthetics, if you don't regularly track a 4600lb suv, the 4 piston calipers work fine. Worthy upgrade for the track no doubt. Let's not forget tire limitations. You can have all the clamping force in the world, but tire selection is going to be the big differentiater.
The OP write up is rather interesting. Seeing the numbers puts things in perspective.

[TacosRule!]

or op can ask brembo for the caliper specs and find out that way. Either way the upgrade is worth it, you slow down faster, look cooler have lower temps on the rotors and with minimal change in bias

[Bimma360]

What I wrote is a fact and not an opinion. Your car's stopping distance is not decreased, period.

This...

Originally Posted by Kevin_The_Clean1

then do a few 120 MPH to zero stops, lets say 3 back to back for good measure. Then begin testing the stopping point differences between these two setups & at that time I'm confident there's a good chance you would have to begin eating crow.

Is explained by this... (you are actually making my point, do you not realize that?)

Originally Posted by Bimma360

(1) A larger pad will absorb more heat, which will take longer to overheat. It will also have a larger contact area with the rotor allowing for a better path to pull the heat out of the pad and dissipate it into the air. Allllllll this means is that the 6 piston pads will take a lot more abuse without fading. It does NOT mean you decrease your stopping distance. That's not how this works. And both the 4 and 6 piston pads have the same CoF, so again... not decreasing your stopping distance.

The test you describe is an extreme condition, and all it does is demonstrate what I wrote for (1). You don't need a test like that to prove anything. Repeatedly stopping your car from 120mph+ (there is actually something that can be said here regarding braking at these speeds, but I am just going to humor you here) will cook the stock pads, and yes it will take longer to cook bigger pads. Is this an upgrade b/c you drive your car like an a-hole on public roads? Sure why not. But no, under equal conditions your car won't brake shorter than stock. Your mod isn't defying the laws of physics, and what is actually pretty common knowledge.

A better test would be to find out the exact speed at which heat comes into play and therefore translates to a reduced stopping distance, the first time. I actually don't know, but bet it's above (maybe a good deal above) 124.2776 mph. Since BMW designs their cars for high speed travel.

Originally Posted by Kevin_The_Clean1

If these factory 6-piston front brake calipers that BREMBO built to BMW's specs weren't considered an upgrade by any means (JUST LIKE YOU SAID) then why are they standard equipment on the M2 / M3 / M4 / M5 / M8 / X5M / X6M... ?

They are not an upgrade in the context I described, I can't help you if you don't want to accept that. All of the cars you listed above's braking systems were designed and more importantly tuned for not all encompassing reasons. It's mostly b/c of weight for the big X's. You are making a false equivalency. BMW designed the entire braking systems of these cars with the 6 pistons. And the brake tuning between every single one of these cars is different despite the fact that they share some of the same braking components. Could BMW have put the 6 pistons on the X3M? Of course. Would have it been a performance increase? Yes, on the track. Would have it decreased the stopping distance? No. That's why they put the 4-piston on the X3M. B/c 99.9% of people won't take an X to the track.

Fun fact, C&D recorded the same braking distance 70-0mph for the X3M as the M3. No, a 6 piston X3M is not going to out brake an M3 in the test above, or in any other context.

Lastly, your perception of what is happening to your car vs reality can actually be two completely different things. This much is self evident from the very first thing I quoted you on in my previous post.

I will give you this. If you are a tool doing a buck forty on public roads and that in and of itself is the reason to classify any related mod "highly worthy." Then you are right.

[Bimma360]

Originally Posted by 95wildtt

I think you are both correct, and there really is no need to throw stones at each other over this topic...

Botton line is, if you want to upgrade, do it... there are lots of benefits for YOU and your F9x, and that's all that really matters, right?

Eh, his initial reply was condescending. In fact most of his reply's I have read in other threads seem to be. I purposefully didn't make any conclusions as to not turn this thread into what it actually turned into... until he responded.

We agree on the fact that bigger pads resist brake fade, and everything that comes from that. Everything else he says is categorically false. A misinformed dude making absolute statements based on his butt dyno, without actually understanding why he is experiencing what he is experiencing and falsely equating it to things he shouldn't.

Originally Posted by Edgar_FriendlyX3M

The OP write up is rather interesting. Seeing the numbers puts things in perspective.

Thanks dude. The fun part is to empirically see how (if possible) we can account for the bias shift.

Originally Posted by TacosRule!

or op can ask brembo for the caliper specs and find out that way. Either way the upgrade is worth it, you slow down faster, look cooler have lower temps on the rotors and with minimal change in bias

Haha you are messing with me right? The info is in the first post, no need to "ask Brembo." You are not going to slow down faster unless you are under conditions that will over heat the front pads (stock). All things being equal you will not slow down faster. This is physics 101.

[Kevin_The_Clean1]

So I've been called an A-hole & a tool for driving my X3 M quicker than most when no ones around. LMAO Guess you drive at or near the speed limit all day. That's certainly a first & clearly displays the level of underlying of maturity the op is capable of. That in itself is pure slander. I've never stooped to that level & will continue to take the high road. Job well done at revealing true colors & calling another adult childish names.

Once the stock calipers & pads get toasty during repeated sporty driving sessions (which happens more often especially in the summer & at higher speeds) their weaknesses begin to show themselves in a very obvious & quick manner. I for one chose to go with calipers that were built to handle much more abuse & were built for more aggressive street / track applications.

When the brakes get hot, the upgraded units clearly display their higher threshold of heat absorption capability & will remain much more predictable & stable for longer periods of time. In turn, once hotter temps are reached, yes the 6-piston units will perform more consistently & provide shorter stopping distances (compared to their weaker / inferior counterparts at the same temp that can't handle & dissipate as much thermal energy).

When you look at the C&D report to show metrics on one single 70-0 MPH stop, sure the stock brakes do a great job & of course they are fine for most light street applications. But for those who wish to extract more performance & dynamic driving capabilities from their high output F97, they will ditch the 4-pot units with those pathetically small pads that belong on a 2 or 3 series. Not an SUV that weighs a touch more than a fully equipped M5.

Does you average owner typically get their brakes hot enough to reach brake fades temps... ? Probably not. But to firmly & consistently deny that the 6-piston calipers are a great upgrade for those that push their X3 M's hard is false information. Do you ever factor in your level of "personal bias" when you run your bias calculations?? Of course not. The 6-piston calipers take much longer to reach brake fade temps & maintain their composure during a much wider range of driving styles. I bet you'll more than likely deny that too because it doesn't fit your narrative.

Does one 70-0 MPH stop really prove much, sure it does. But beyond that, you have no idea the substantial improvement the 6-piston units with the much larger pad provides during spirited drives. I would love to see two identical X3 M's compared on the same track with the same tires on the same day with the same driver. Do that same 70-0 MPH stop a few times. By the 4-5th time, then measure the overall stopping distance difference between the two since you're so married to the fact that "that's not how it works..."

^^^ Then, you'll begin to see a clear difference between the two vastly different setups (you continue to quote are a complete waste) & we could finally put this to rest. When cars are driven hard, larger calipers with substantially larger pads (same CoF) will help that said car maintain consistent stopping distance for a much longer period of time. So yes, shorter stopping distances will be achieved by the more stout system when the weaker of the two has been pushed into or passed its fully heat soaked zone.

We can agree to disagree for as log as you like. But I have a feeling the OP will stand by his statements & defend this to the death. You have some great points & note taken. But when you discredit something you've never seen, experienced or tested out on your own vehicle, you can't say what you want about it & not be critiqued a touch. Fair game, right? You do have some valid points. And I do agree with you on where is the reference point in standards being employed for the iSweep CoF rating on their pads. That's pretty cut & dry. I do think the CoF for their factory pads comparison in that chart was slightly skewed to make the data look more impactful.

Bottom line, I think some of the words I chose to use may have been taken out of context. What I should have said is something closer to this, when the factory 4 pot calipers have been pushed to their limits, the 6 pot units in direct replacement will allow for spirited runs over a longer course of time. The 6 pots are clearly less prone to brake fade. So at the end of the day, chances are the 6 pots will experience brake fade a lot less often & therefore help to achieve more consistent stopping distances for us super eager drivers. There, are you happy now man... ? LOL

[Bimma360]

Haha I should know better than to argue with someone on the internet. I guess I need a reminder every 5-10 years.

From my very first reply to you (in bold red and in bold black)...

Originally Posted by Bimma360

I wouldn't call this mod "highly worthy." The ONLY gain with this mod is reducing brake fade under repeated abuse. For someone that takes their X3M to the track (not the drag strip), I would say that this is probably worthwhile. And if you are someone that tends to cook their stock pads on the street, sure. But for just about all other street cars this is a giant waste of money, and not much of an upgrade. In fact all you are doing is skewing your factory brake bias, for a gain you will actually rarely experience. Is a 2.4% reduction in front bias negligible? Maybe. But I would hate to find out at 70mph+ in the rain on the highway.

And correspondingly (in bold red and bold black) what you wanted to hear...

Originally Posted by Kevin_The_Clean1

Does you average owner typically get their brakes hot enough to reach brake fades temps... ? Probably not. But to firmly & consistently deny that the 6-piston calipers are a great upgrade for those that push their X3 M's hard is false information. Do you ever factor in your level of "personal bias" when you run your bias calculations?? Of course not. The 6-piston calipers take much longer to reach brake fade temps & maintain their composure during a much wider range of driving styles. I bet you'll more than likely deny that too because it doesn't fit your narrative.

You sure love those eye roll emoji's. That's cute.