[exE36M3]

Hey guys, I was shopping for some rotors - comparing the factory M Sport rotors versus the Brembo ones. The price difference is staggering.

So specs are 370mm x 30mm for M Sport Brake 435i (2014-2017)
Slotted, Dimpled, and 2-piece design ("floating")

Front set only:
Brembo : $350
OEM M Motorport: $650

So any of you guys go this route?

Brembo (ebay)
https://www.ebay.com/itm/Brembo-Pair...1&isGTR=1#shId




BMW Motorsport (Turner)
https://www.turnermotorsport.com/p-3...2-f33-f34-f36/

[FaRKle!]

I don't believe those are floating. They use the same riveted design as the OE ones (the rivets don't allow float).

I can't imagine these Brembos would be significantly different from the Pagid 355120771. About the same price for a set.

Also, eBay has 10% eBay Bucks back today through Thurs.

[johnung]

Originally Posted by percychow

Hey guys, I was shopping for some rotors - comparing the factory M Sport rotors versus the Brembo ones. The price difference is staggering.

So specs are 370mm x 30mm for M Sport Brake 435i (2014-2017)
Slotted, Dimpled, and 2-piece design ("floating")

Front set only:
Brembo : $350
OEM M Motorport: $650

So any of you guys go this route?

Brembo (ebay)
https://www.ebay.com/itm/Brembo-Pair...8;isGTR=1#shId




BMW Motorsport (Turner)
https://www.turnermotorsport.com/p-3...2-f33-f34-f36/

Those aren't 370x30 floating rotors that you are considering. All floating rotors are 2-piece, but not all 2-piece are floating.

2-piece riveted isn't a huge advantage over a high quality one-piece like the dimpled & slotted 370's from Zimmermann below for just $230/pair. Gives you the look you want for a lot less without sacrificing quality.

https://www.ecstuning.com/b-zimmerma...4106797603zkt/

There are several two-piece riveted 370x30 rotors in the $350-$500/pair range. They won't look or perform appreciably better than the Zimmermann's above but if you wish to spend more $ they are available. StopTech has some that are high quality.

True floating rotors have a fastening system between the rotor ring and the rotor hat that allows the ring to "float" independently which means it isn't as effected by heat changes. Plus it reduces unsprung and rotating mass weight. Google it if you are interested in engineering details.

Below is a link to a "Semi-Floating" 370mm provides unsprung weight savings and replaceable rotor ring. From ECS for $812/pair

https://www.ecstuning.com/b-ecs-part...09607ecs01akt/

The ultimate true floating rotor in a stock M Sport/M Performance 370mm x 30mm size is from StopTech. Pay extra for coating to avoid rust in holes, slots and side vanes. These are 4-8 week special order. They can be found discounted. Link below.

https://www.buybrakes.com/stoptech-8...ke-upgrade-kit

Attached photos are from my car. Coating is gold when mounted and wears right off pad swept area but remains black in holes and vanes to prevent rust.

I chose true drilled through because they have best bite and shed water during rain. Porsche, McLaren, Mercedes, etc all used drilled rotors. Don't listen to anyone who claims that they crack between holes. Only happens during extreme heat of lap after lap racing.

Slotted rotors bite a little better than plain but not as good as drilled. They tend to be noisy and tear up pads. They are more ideal for high heat lap after lap racing where those things don't matter.

Hope this helps!

[FaRKle!]

Originally Posted by johnung

The ultimate true floating rotor in a stock M Sport/M Performance 370mm x 30mm size is from StopTech. Pay extra for coating to avoid rust in holes, slots and side vanes. These are 4-8 week special order. They can be found discounted. Link below.

https://www.buybrakes.com/stoptech-8...ke-upgrade-kit

Attached photos are from my car. Coating is gold when mounted and wears right off pad swept area but remains black in holes and vanes to prevent rust.

I chose true drilled through because they have best bite and shed water during rain. Porsche, McLaren, Mercedes, etc all used drilled rotors. Don't listen to anyone who claims that they crack between holes. Only happens during extreme heat of lap after lap racing.

Slotted rotors bite a little better than plain but not as good as drilled. They tend to be noisy and tear up pads. They are more ideal for high heat lap after lap racing where those things don't matter.

Hope this helps!

Luckily percychow is local to me so rust isn't something we need to worry about, so we can get away with the cheaper ~$750-800 version of the ARKs.

I don't quite agree with your position on drilled vs slotted, as I've seen plenty of drilled F8x rotors crack between the holes from HPDEs (not racing). I agree it's very unlikely to happen in street driving though.

I have the slotted version of the ARKs, and haven't had any issues with noise. In my experience blank rotors are the worst for noise for both street and track pads. Track pads will always be noisy, but the noise comes on sooner with blanks from my experience.

ARKs do a good job of maintaining a cooler temperature under track use over the OE rotors, and they wear more slowly. I can get through more than a year and a half on track (15-18 days) on ARKs and an endurance pad like RSL-29 or PFC-08. My EBC Red street pads aren't wearing very quickly either. I've had my ARKs for a year and half and when I took a quick measurement on them the other day they were still over 29mm thick.

johnung, you didn't happen to catch the "min thickness" for the ARKs on the inside of the rotor/hat did you? Unfortunately it's not on the side like the OE rotors. Stoptech says these rotors can wear 2mm, greater than the 1.6mm of the OE rotors.

[johnung]

Originally Posted by FaRKle!

Luckily percychow is local to me so rust isn't something we need to worry about, so we can get away with the cheaper ~$750-800 version of the ARKs.

I don't quite agree with your position on drilled vs slotted, as I've seen plenty of drilled F8x rotors crack between the holes from HPDEs (not racing). I agree it's very unlikely to happen in street driving though.

I have the slotted version of the ARKs, and haven't had any issues with noise. In my experience blank rotors are the worst for noise for both street and track pads. Track pads will always be noisy, but the noise comes on sooner with blanks from my experience.

ARKs do a good job of maintaining a cooler temperature under track use over the OE rotors, and they wear more slowly. I can get through more than a year and a half on track (15-18 days) on ARKs and an endurance pad like RSL-29 or PFC-08. My EBC Red street pads aren't wearing very quickly either. I've had my ARKs for a year and half and when I took a quick measurement on them the other day they were still over 29mm thick.

johnung, you didn't happen to catch the "min thickness" for the ARKs on the inside of the rotor/hat did you? Unfortunately it's not on the side like the OE rotors. Stoptech says these rotors can wear 2mm, greater than the 1.6mm of the OE rotors.

Hey,
Thanks for sharing your experience.

My rust comment was because the full floating StopTechs have an option for uncoated at about $100 less. Not a great deal if you spend a lot for rotors and they're rusty.

I know that drilled can crack. I see plenty of micro-cracks on Porsche rotors at car shows. My comments were more trying to get some details out there because I read blanket anti-drilled statements with zero knowledge/understanding behind it. Someone just repeating a line that they heard.

My comment about slotted rotors actually I was passing on from my local BMW Indy owner whose been doing them for 25 years. He hates slotted with a passion because of high rate of returns due to noise and early pad wear.

Comments about bite levels of drilled, slotted, plain come from conversations with Dave Z. from Zeckhausen Racing. Incredibly knowledgeable guy from both an engineering and race experience perspective.

It's a shame we are on opposite coasts. I'd enjoy checking out your racing scene. Take care! 🏎

[johnung]

Originally Posted by FaRKle!

Luckily percychow is local to me so rust isn't something we need to worry about, so we can get away with the cheaper ~$750-800 version of the ARKs.

I don't quite agree with your position on drilled vs slotted, as I've seen plenty of drilled F8x rotors crack between the holes from HPDEs (not racing). I agree it's very unlikely to happen in street driving though.

I have the slotted version of the ARKs, and haven't had any issues with noise. In my experience blank rotors are the worst for noise for both street and track pads. Track pads will always be noisy, but the noise comes on sooner with blanks from my experience.

ARKs do a good job of maintaining a cooler temperature under track use over the OE rotors, and they wear more slowly. I can get through more than a year and a half on track (15-18 days) on ARKs and an endurance pad like RSL-29 or PFC-08. My EBC Red street pads aren't wearing very quickly either. I've had my ARKs for a year and half and when I took a quick measurement on them the other day they were still over 29mm thick.

johnung, you didn't happen to catch the "min thickness" for the ARKs on the inside of the rotor/hat did you? Unfortunately it's not on the side like the OE rotors. Stoptech says these rotors can wear 2mm, greater than the 1.6mm of the OE rotors.

Thanks for the heads up. I didn't know that StopTech is claiming 2mm of rotor wear material instead of the stock wear amount of 1.6mm.

I did not notice anything written on them. I did take the attached photos before installation. I didn't spot anything on the photos. It will be on a lift at Kies in a few weeks. I'll try to use a flashlight to see if I can spot anything.

[FaRKle!]

Originally Posted by johnung

It's a shame we are on opposite coasts.

Yes, it is a shame. I think you'd enjoy the technical dives we take into these platforms.

Originally Posted by johnung

Thanks for the heads up. I didn't know that StopTech is claiming 2mm of rotor wear material instead of the stock wear amount of 1.6mm.

I did not notice anything written on them. I did take the attached photos before installation. I didn't spot anything on the photos. It will be on a lift at Kies in a few weeks. I'll try to use a flashlight to see if I can spot anything.

Stoptech tech support told me the min thickness should be on the inside of the casting when I enquired about what the max wear is. They also said that the difference between replacement friction ring PNs ending in ".01" and ".99" is that the ".01" is the ring only and the ".99" is the ring and fastening hardware (which should also be replaced when the rings are changed).

[jh_f30]

I don't have M Performance brakes, but I recently ordered the 340mm dimpled & slotted Brembo rotors. Just arrived today. Also have some Hawk HPS 5.0 pads scheduled to arrive tomorrow.

Brembo 09.C398.13 Front Disc Brake Rotor https://www.amazon.com/dp/B075Y3Z562..._5.C-DbXPM4BDV

My current stock rotors have over 124k miles on them. No track use, occasional spirited driving. Didn't measure them, but they're pretty glazed and I figured it was time. Plus, I want some more initial bite from my brakes.

[exE36M3]

Gentlemen - first off, thank you for responding to this thread. Forgive the floating rotors comment. I meant 2 piece design, but regardless, all the info here has been outstanding and helpful. I concur about slotted and drilled adding increased pad wear. I drive such a laughably small commute that I can afford to consider that as an option.

jh_f30, I think by the time we have our suspension meet-up, your brake set-up should have arrived. Would appreciate a ride in your car to see if there is any change in braking character.

Farkle - as always, thank you for offering your input. I was looking at the Pagid's too. Liking those prices.

Johnung - love that look, but my driving wouldn't even due justice to the artwork of that rotor

[jh_f30]

Originally Posted by percychow

Gentlemen - first off, thank you for responding to this thread. Forgive the floating rotors comment. I meant 2 piece design, but regardless, all the info here has been outstanding and helpful. I concur about slotted and drilled adding increased pad wear. I drive such a laughably small commute that I can afford to consider that as an option.

jh_f30, I think by the time we have our suspension meet-up, your brake set-up should have arrived. Would appreciate a ride in your car to see if there is any change in braking character.

Farkle - as always, thank you for offering your input. I was looking at the Pagid's too. Liking those prices.

Johnung - love that look, but my driving wouldn't even due justice to the artwork of that rotor

Rotors and pads installed yesterday.

[mike082802]

Originally Posted by johnung

Those aren't 370x30 floating rotors that you are considering. All floating rotors are 2-piece, but not all 2-piece are floating.

2-piece riveted isn't a huge advantage over a high quality one-piece like the dimpled & slotted 370's from Zimmermann below for just $230/pair. Gives you the look you want for a lot less without sacrificing quality.

https://www.ecstuning.com/b-zimmerma...4106797603zkt/

There are several two-piece riveted 370x30 rotors in the $350-$500/pair range. They won't look or perform appreciably better than the Zimmermann's above but if you wish to spend more $ they are available. StopTech has some that are high quality.

True floating rotors have a fastening system between the rotor ring and the rotor hat that allows the ring to "float" independently which means it isn't as effected by heat changes. Plus it reduces unsprung and rotating mass weight. Google it if you are interested in engineering details.

Below is a link to a "Semi-Floating" 370mm provides unsprung weight savings and replaceable rotor ring. From ECS for $812/pair

https://www.ecstuning.com/b-ecs-part...09607ecs01akt/

The ultimate true floating rotor in a stock M Sport/M Performance 370mm x 30mm size is from StopTech. Pay extra for coating to avoid rust in holes, slots and side vanes. These are 4-8 week special order. They can be found discounted. Link below.

https://www.buybrakes.com/stoptech-8...ke-upgrade-kit

Attached photos are from my car. Coating is gold when mounted and wears right off pad swept area but remains black in holes and vanes to prevent rust.

I chose true drilled through because they have best bite and shed water during rain. Porsche, McLaren, Mercedes, etc all used drilled rotors. Don't listen to anyone who claims that they crack between holes. Only happens during extreme heat of lap after lap racing.

Slotted rotors bite a little better than plain but not as good as drilled. They tend to be noisy and tear up pads. They are more ideal for high heat lap after lap racing where those things don't matter.

Hope this helps!

seems centric has one too:
Part Number: 129906-05878975
Notes: AeroRotor - Black Hat - No Rotor Coating - Slotted Right -- 370mm Front Disc; Dimpled & Slotted Disc; M Sport Brakes

https://www.partsgeek.com/catalog/20...ake_rotor.html

a few down from the top, not a bad price either

also i was under the impression the rotors with alluminum rivited hats weighed a few pounds less and rockauto has them for 136
https://www.rockauto.com/en/parts/pa...771,rotor,1896

i am probably going with one of these 2.

[johnung]

Originally Posted by mike082802

seems centric has one too:
Part Number: 129906-05878975
Notes: AeroRotor - Black Hat - No Rotor Coating - Slotted Right -- 370mm Front Disc; Dimpled & Slotted Disc; M Sport Brakes

https://www.partsgeek.com/catalog/20...ake_rotor.html

a few down from the top, not a bad price either

also i was under the impression the rotors with alluminum rivited hats weighed a few pounds less and rockauto has them for 136
https://www.rockauto.com/en/parts/pa...771,rotor,1896

i am probably going with one of these 2.

Centric and StopTech are owned by the same company. Centric is their lower end line and StopTech is the higher quality line. There just isn't enough information in the link that you sent to tell how they compare. Without seeing photos of the backs it's difficult to tell if they are the same style. The only thing was that Centric isn't coated. I was warned to order the coated model because the uncoated can get rusty.

I'd suggest calling StopTech with both part numbers and ask them what the differences are. (310) 933-1100

The other link to the Pagid rotors, they seem exactly like Zimmermann rotors that I've seen, but that's just from a website listing.

The two options that you have identified are very different price points.

[BrysonDM]

With drilled and slotted rotors, how do they fair up in cold climate/weather? And I truly mean cold as in -40 both Celsius and Fahrenheit. Because I've already got 3 feet of snow in my front yard, and its been hitting -35 already.

[mike082802]

Originally Posted by johnung

The other link to the Pagid rotors, they seem exactly like Zimmermann rotors that I've seen, but that's just from a website listing.

The two options that you have identified are very different price points.

just throwing out other options. the zimmerman are good rotors no doubt but not 2 piece like the pagid with the aluminum hats which "should" save some weight. for me given at similar price point and both great quality i would always go with the two piece just for the weight savings.

[johnung]

Originally Posted by BrysonDM

With drilled and slotted rotors, how do they fair up in cold climate/weather? And I truly mean cold as in -40 both Celsius and Fahrenheit. Because I've already got 3 feet of snow in my front yard, and its been hitting -35 already.

OMG sounds like we will find out. You are our cold rotor test case. Pretty soon you'll be raking in the money renting space for vaccine storage.

[johnung]

Originally Posted by mike082802

just throwing out other options. the zimmerman are good rotors no doubt but not 2 piece like the pagid with the aluminum hats which "should" save some weight. for me given at similar price point and both great quality i would always go with the two piece just for the weight savings.

I hear what you are saying. All things being equal I would choose a lighter 2-piece rotor too.

I don't know if it's just brilliant marketing but StopTech claims that their directional internal vanes are designed for optimal cooling. I've read their descriptions and looked closely at the product so I believe that it is an advantage for StopTech rotors.

I was starting to fixate on weight until I started really looking up weights and weighing parts like rotors, wheels, tires. My car came with front rotors that were 340mm x 30mm. The plain one-piece are about 24.0lbs/10.90kg. But the two-piece are only 22.0lbs/10.00kg.

That 2lb weight savings sounded great. But then I got the opportunity to upgrade to Front 370mm x 30mm. I looked up the weight of those: 29.1lbs/13.20kg!

But no way would I not install the bigger front brakes, just because their rotors weighed so much more. The extra rotor mass actually gives the 370 brakes a big advantage over the 340's. They can dissipate a lot more heat to prevent brake fade.

Everything is a trade-off.

My 400M 8.0"x 18" wheels are relatively heavy. If I wanted lighter forged wheels I'd get 763's that are 9.0"x 19". Super light wheels, but then the bigger 255/35-19 tires are a lot heavier! Can't win on weight but those wider tires would handle and perform so much better!

As it is I'm holding out until I win the lottery to get those 763 wheels in Frozen Gold! So I went for 245/40-18 Michelin Pilot Sport 4S tires on the old stock 400M wheels. Handles amazing!

So after going round and round researching all of the various component weights, I did get the brake caliper upgrades. HaHa, and I ended up with just about the lightest rotor that their is...the StopTech Crossdrilled full floating 370x30. With the Hawk 5.0 pads, they stop on a dime!