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      10-18-2017, 03:53 PM   #1
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Question Larger rotor on m sport brakes 440i

Hello, so i recently bought new rotors but i bought rotors for the 600$ option m sport brakes. I guess i still have the stock brakes. But the front caliper is the same? The only difference is the rear caliper. Could i fit the larger rotor on the front and then just exchange the rear rotors for the a smaller size? The front rotor thats on is 337mm could i fit my 370mm rotor on that caliper without problems?
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      10-18-2017, 04:04 PM   #2
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Quote:
Originally Posted by Tatu_F32 View Post
Hello, so i recently bought new rotors but i bought rotors for the 600$ option m sport brakes. I guess i still have the stock brakes. But the front caliper is the same? The only difference is the rear caliper. Could i fit the larger rotor on the front and then just exchange the rear rotors for the a smaller size? The front rotor thats on is 337mm could i fit my 370mm rotor on that caliper without problems?
No. While the caliper is the "same", it is not. The arc at the base of the caliper is different between the 340 and 370mm variants. This allows them to fit on the larger diameter caliper by sticking out further.
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      10-18-2017, 04:12 PM   #3
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Quote:
Originally Posted by stxf30 View Post
No. While the caliper is the "same", it is not. The arc at the base of the caliper is different between the 370 and 370mm variants. This allows them to fit on the larger diameter caliper by sticking out further.
ok! Iv also read that the BBK is purely for aesthetics. Would it be more worthy to just buy dimpled/slotted rotors that are the same size? Iv read there isnt really any performance difference. For performance that would fall into the hands of tires and pads, correct?
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      10-19-2017, 10:31 AM   #4
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Quote:
Originally Posted by Tatu_F32 View Post
ok! Iv also read that the BBK is purely for aesthetics. Would it be more worthy to just buy dimpled/slotted rotors that are the same size? Iv read there isnt really any performance difference. For performance that would fall into the hands of tires and pads, correct?
You're more or less correct; generally speaking, slotted/dimpled rotors are a waste of money. Better bang for buck is a blank rotor with the extra money spent on tires and pads.
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      10-19-2017, 10:41 AM   #5
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Quote:
Originally Posted by Tatu_F32 View Post
ok! Iv also read that the BBK is purely for aesthetics. Would it be more worthy to just buy dimpled/slotted rotors that are the same size? Iv read there isnt really any performance difference. For performance that would fall into the hands of tires and pads, correct?
There is going to be a "performance difference" its just a matter of whether its a difference for your style of driving
slightly better braking distance
better brake fade

If you are looking for aesthetics why not just paint the calipers and get slotted rotors
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      10-19-2017, 10:48 AM   #6
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Quote:
Originally Posted by insanecoder View Post
There is going to be a "performance difference" its just a matter of whether its a difference for your style of driving
slightly better braking distance
better brake fade

If you are looking for aesthetics why not just paint the calipers and get slotted rotors
That's arguable; you're paying more money for less rotor. Dimples and slots wear down pads faster, but the little added performance they offer (if any) is generally defeated by the fact that there's less rotor available that would normally aid in absorbing heat. I'd insist that the opposite is true; blank rotors offer the superior brake fade resistance.
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      10-19-2017, 10:51 AM   #7
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Quote:
Originally Posted by Bestodabest View Post
That's arguable; you're paying more money for less rotor. Dimples and slots wear down pads faster, but the little added performance they offer (if any) is generally defeated by the fact that there's less rotor available that would normally aid in absorbing heat. I'd insist that the opposite is true; blank rotors offer the superior brake fade resistance.
I said if hes after aesthetics just paint the calipers and get slotted rotors for looks not performance per se.. aesthetics
As far as fade performance there is somewhere a trade-off between slotted cooling and the larger rotor surface probably depends on application.. street driving will likely not expose this and the surface area taken by the slots is generally not that much
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      10-19-2017, 10:53 AM   #8
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Quote:
Originally Posted by insanecoder View Post
I said if hes after aesthetics just paint the calipers and get slotted rotors for looks not performance per se.. aesthetics
Agreed; I wouldn't recommend them for any other reason.
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      10-19-2017, 11:48 AM   #9
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Quote:
Originally Posted by Tatu_F32 View Post
ok! Iv also read that the BBK is purely for aesthetics. Would it be more worthy to just buy dimpled/slotted rotors that are the same size? Iv read there isnt really any performance difference. For performance that would fall into the hands of tires and pads, correct?
Quote:
Originally Posted by Bestodabest View Post
You're more or less correct; generally speaking, slotted/dimpled rotors are a waste of money. Better bang for buck is a blank rotor with the extra money spent on tires and pads.
Quote:
Originally Posted by insanecoder View Post
There is going to be a "performance difference" its just a matter of whether its a difference for your style of driving
slightly better braking distance
better brake fade

If you are looking for aesthetics why not just paint the calipers and get slotted rotors
BBK isn't purely for aesthetics. I would argue that it's for performance in spirited driving and track environments.

I'm glad I factory ordered the $650 M Sport Brake Option for my 335i. I now run F8X M3/M4 front and rear pads in it during the summer and it's excellent at the track.
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      10-19-2017, 02:14 PM   #10
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Quote:
Originally Posted by Bestodabest
Quote:
Originally Posted by Tatu_F32 View Post
ok! Iv also read that the BBK is purely for aesthetics. Would it be more worthy to just buy dimpled/slotted rotors that are the same size? Iv read there isnt really any performance difference. For performance that would fall into the hands of tires and pads, correct?
You're more or less correct; generally speaking, slotted/dimpled rotors are a waste of money. Better bang for buck is a blank rotor with the extra money spent on tires and pads.
The dimpled/slotted rotor should give better response on wet conditions and reduce fading when brake pads are getting really hot.

Flat surface in normal condition are better because more square inches surface to the brakes pad (no dimples, no slots).

So both setups have pros and cons. No light without shade.
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      10-19-2017, 04:09 PM   #11
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Quote:
Originally Posted by oceanview View Post
The dimpled/slotted rotor should give better response on wet conditions and reduce fading when brake pads are getting really hot.

Flat surface in normal condition are better because more square inches surface to the brakes pad (no dimples, no slots).

So both setups have pros and cons. No light without shade.
I could see your wet conditions arguement being viable; mind you pads are normally slotted, and if i remember correctly, most modern BMW's utilize technology that's supposed to actuate your brakes every so often to purge water from the friction surfaces.

I disagree with your opinion on brake fade, though. I'm not convinced that slots or dimples will prevent the brake pads from overheating better than blanks.

A blank rotor has more volume, and can better absorb/dissipate the heat from hard braking. Brake pad materials also produce less off-gassing than pads of the past, so I'm not convinced brake fade would result from the use of blanks vs slotted/dimpled.

It should also be mentioned that slotted/dimpled rotors chew through pads faster, and in my experience are more prone to warping and/or cracking.

OP, assuming you're going for aesthetics, buy slotted/dimpled rotors. If you prefer function over form, and more money in your pocket, then stick with blanks.
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      10-19-2017, 04:27 PM   #12
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Quote:
Originally Posted by Bestodabest View Post
I could see your wet conditions arguement being viable; mind you pads are normally slotted, and if i remember correctly, most modern BMW's utilize technology that's supposed to actuate your brakes every so often to purge water from the friction surfaces.

I disagree with your opinion on brake fade, though. I'm not convinced that slots or dimples will prevent the brake pads from overheating better than blanks.

A blank rotor has more volume, and can better absorb/dissipate the heat from hard braking. Brake pad materials also produce less off-gassing than pads of the past, so I'm not convinced brake fade would result from the use of blanks vs slotted/dimpled.

It should also be mentioned that slotted/dimpled rotors chew through pads faster, and in my experience are more prone to warping and/or cracking.

OP, assuming you're going for aesthetics, buy slotted/dimpled rotors. If you prefer function over form, and more money in your pocket, then stick with blanks.
Again, agreeing here with Bestodabest .
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      10-19-2017, 05:05 PM   #13
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Quote:
Originally Posted by Bestodabest

I could see your wet conditions arguement being viable; mind you pads are normally slotted, and if i remember correctly, most modern BMW's utilize technology that's supposed to actuate your brakes every so often to purge water from the friction surfaces.

I disagree with your opinion on brake fade, though. I'm not convinced that slots or dimples will prevent the brake pads from overheating better than blanks.

A blank rotor has more volume, and can better absorb/dissipate the heat from hard braking. Brake pad materials also produce less off-gassing than pads of the past, so I'm not convinced brake fade would result from the use of blanks vs slotted/dimpled.

It should also be mentioned that slotted/dimpled rotors chew through pads faster, and in my experience are more prone to warping and/or cracking.
It's not my argument but the one of EBC Brakes, a brakes manufacturer.

https://ebcbrakes.com/ebc-news/ebc-p...-sport-rotors/

F3x does dry brake only with rain sensor activated.
In the E46 however the wet braking reaction was way better due to the slots.
And dimpled rotors should not be cracking, which is a known problem of drilled rotors.

I took the F3x new with the M Performance Brakes so I can't compare with the normal rotor.
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      10-19-2017, 05:24 PM   #14
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Quote:
Originally Posted by oceanview View Post
It's not my argument but the one of EBC Brakes, a brakes manufacturer.

https://ebcbrakes.com/ebc-news/ebc-p...-sport-rotors/

Don't know if the F3x does dry brake. In the E46 however the wet braking reaction was way better due to the slots.
And dimpled rotors should not be cracking, which is a known problem of drilled rotors.

I took the F3x new with the M Performance Brakes so I can't compare with the normal rotor.
They're not technically wrong, but try to remember that their job is to sell brake components. The advantage their describing is probably a fraction of a percentage. Hardly worth the premium that dimpled rotors command.

Also remember that as rotors wear, the dimples grow smaller. How often do you find yourself driving in the rain? Under a hard stop, I'd be more concerned with my tires losing traction than the fraction of a second that it takes for the brakes to dry off.
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      10-19-2017, 08:23 PM   #15
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Larger rotors w/ brackets that are farther away from the axis of the wheel = larger sweep area per rotation.
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      10-19-2017, 08:38 PM   #16
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Personally for me when its time, the slotted rotors are going on under the brembos w/better pads as well
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      10-20-2017, 01:06 AM   #17
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Quote:
Originally Posted by insanecoder View Post
Personally for me when its time, the slotted rotors are going on under the brembos w/better pads as well
Thats what i just did!
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      11-02-2017, 12:49 PM   #18
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Quote:
Originally Posted by Bestodabest View Post
I could see your wet conditions arguement being viable; mind you pads are normally slotted, and if i remember correctly, most modern BMW's utilize technology that's supposed to actuate your brakes every so often to purge water from the friction surfaces.

I disagree with your opinion on brake fade, though. I'm not convinced that slots or dimples will prevent the brake pads from overheating better than blanks.

A blank rotor has more volume, and can better absorb/dissipate the heat from hard braking. Brake pad materials also produce less off-gassing than pads of the past, so I'm not convinced brake fade would result from the use of blanks vs slotted/dimpled.

It should also be mentioned that slotted/dimpled rotors chew through pads faster, and in my experience are more prone to warping and/or cracking.

OP, assuming you're going for aesthetics, buy slotted/dimpled rotors. If you prefer function over form, and more money in your pocket, then stick with blanks.
Couldn’t agree more!
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      12-17-2017, 10:15 PM   #19
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Similar question. Can someone help me with this?

- I have a 2015 335i XDrive, stock brakes.
- My Dad has a 2018 440i XDrive, blue M-SPORT brakes

If he puts on an M-Performance kit (for him, primarily for M caliper color and drilled/slot rotors)...

Will his 2018 440i M-Sport blue brakes (and rotor swapped also if needed) fit on my 2015 335i??????
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      12-17-2017, 10:52 PM   #20
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For the 2015 year (and 2014 as well I think), 335's had a rotor/sizing change from
Stock=340mm front, 330mm rear, to:
Blue M Sport= 375mm front, 345mm rear.

I can't seem to find rotor size for 2018 440i stock brakes or M-SPORT brakes, whether they are slightly different or the same.

Then what I need to know is if there are any different parts/brackets/mounting needed for the swap, or if I can just plug & play swap the stock 335i calipers for the blue??? (+/- rotors).
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