[Ifellapart]

This doesn't seem normal. I measured my old rotors and they're 370mm in diameter, as are these. but these have a small hat and more surface are...but the way the caliper sits, it does not fully cover the rotor...is this normal?...

[imfritz328i]

compress the pistons and slide it all the way on?

[im_an_alien]

The answer to that is right there in your question...the rotors have more real estate than is required for those particular pads, hence the extra space...that will not wear well. Those may be multi application rotors, ie they fit a multitude of vehicles with similar bolt patterns and different pad designs

[Ifellapart]

Originally Posted by im_an_alien

The answer to that is right there in your question...the rotors have more real estate than is required for those particular pads, hence the extra space...that will not wear well. Those may be multi application rotors, ie they fit a multitude of vehicles with similar bolt patterns and different pad designs

well said.

I ordered them through tire rack. they stated they would only fit vehicles with m sport brakes. I didn't bother measuring them till just now. My oem brakes measure at about 370mm in diamater. the Stoptechs are about 340... the length of the surface area seems to be about the same coincidentally but the hat size is different making the overal rotor smaller...no idea what they sent me

[im_an_alien]

Yup, I believe the 2 series had blue m sport brakes with 340mm rotors, while the 3er had 370mm rotors. I thought those were 370mm rotors as per the original post, but it's clear the rotors are too small for the calipers.
Post #3 has a good pic showing difference btw the 340mm vs 370mm calipers...they are essentially the same but mount differently to account for the rotor size diameter.
https://f30.bimmerpost.com/forums/sh....php?t=1358968

[Gen13 F36]

Originally Posted by Ifellapart

This doesn't seem normal. I measured my old rotors and they're 370mm in diameter, as are these. but these have a small hat and more surface are...but the way the caliper sits, it does not fully cover the rotor...is this normal?...

Just looking at the photo, you got the wrong rotor.

Tirerack should just continue selling tires related product. Long time ago they sent me wrong brake rotors and pads twice for my previous car. I wish they have a better way of identifying my vehicle. Just imagine your car on jack stand with brakes fully disassembled and find out the part don't fit.

I like buying tires there... maybe tpms... but nothing else.

[Ifellapart]

Originally Posted by Gen13 F36

Just imagine your car on jack stand with brakes fully disassembled and find out the part don't fit.

I like buying tires there... maybe tpms... but nothing else.

literally me. there goes most of my day for nuthin.

oh well, wouldn't be working on cars if something didn't go wrong.

thanks for the input guys.

[johnung]

Originally Posted by Ifellapart

literally me. there goes most of my day for nuthin.

oh well, wouldn't be working on cars if something didn't go wrong.

thanks for the input guys.

It's apparent that you were sent 340mm rotors when your calipers require 370mm rotors.

The ultimate fault for this actually lies with BMW. They created the "M Sport" marketing term. It must have been successful because they use it everywhere, on many different models and for many types of components.

The "M Sport" term remains in many descriptions as if it was specific, even when it doesn't narrow things down that much. Those descriptions get handed down to aftermarket parts manufacturers, wholesalers and retailers. So it's easy for something that is confusing to be spread everywhere to confuse everyone.

In the case of the F3x 335i/340i front brakes, there are two flavors. Both use Brembo 4-piston calipers that at first glance appear to be identical. They use the exact same size brake pads, exact same part number! Their pins and clips are also identical. Internally, they use identical 40mm pistons, seals and dust caps.

They differ in two ways. The casting on the larger one is stretched out by 15mm so that it goes over a 370mm X 30mm rotor. And it is painted blue. It's obvious when you look on the back of the caliper in raised letters on the casting it say "370/380".

(These same calipers are used on the M3/M4 over 380mm rotors because the caliper points are 5mm further from the center. NO, you can mount 380mm rotors on an F3x.)

These larger blue calipers over 370x30 rotors are sold as an "M Sport Brakes" option for ~$600 on the sticker. If you enter the VIN into the mdecoder website, it will have a line item that says:

S2NHA M SPORT BRAKES

Now, the smaller front caliper, "standard brakes", for the F3x 335i/340i is also a Brembo 4-piston unit, but it goes over the smaller 340mm X 30mm rotor. And it is painted grey to distinguish it from the blue "M Sport" brakes. On the back of the caliper casting in raised lettering it says "340".

Entering the VIN into the mdecoder website does not show a line item code for these "standard brakes", but in other locations I have seen them referred to as P337A. In some documentation, BMW refers to P337A as a model of "M Sport" brakes. I believe this gets proliferated down to some parts descriptions.

I believe that the S2NHA and P337A are coded the same in the brake front/rear bias also. That may be another reason that they are both referred to as "M Sport".

Just when that all may have begun to make sense, if you had say a 328i and ordered M Sport brakes you would not receive the same components. Mdecoder might list S2NHA and your brakes would be blue, but the front blue calipers would actually be over 340mm X 30mm rotors.

So TireRack or any other retailer would be correct in selling 340mm rotors and referring to them as M Sport Brake rotors- if they were meant to fit on a 328i.

The key to understanding F3x brakes is that the rotor sizes are all unique to a particular caliper, even if those calipers look similar or have similar names. So never purchase by name. Always purchase by the brake's rotor size. I have complained to some retailers that they do not include the rotor size in their descriptions so sometimes it is impossible to tell if the part is correct or not.

Fronts rotors can be 370x30, 340x30, 330x24, 312x24
Rears rotors can be 345x24, 330x20, 300x20

Hope this is helpful to someone!

[Gen13 F36]

Originally Posted by johnung

It's apparent that you were sent 340mm rotors when your calipers require 370mm rotors.

The ultimate fault for this actually lies with BMW. They created the "M Sport" marketing term. It must have been successful because they use it everywhere, on many different models and for many types of components.

The "M Sport" term remains in many descriptions as if it was specific, even when it doesn't narrow things down that much. Those descriptions get handed down to aftermarket parts manufacturers, wholesalers and retailers. So it's easy for something that is confusing to be spread everywhere to confuse everyone.

In the case of the F3x 335i/340i front brakes, there are two flavors. Both use Brembo 4-piston calipers that at first glance appear to be identical. They use the exact same size brake pads, exact same part number! Their pins and clips are also identical. Internally, they use identical 40mm pistons, seals and dust caps.

They differ in two ways. The casting on the larger one is stretched out by 15mm so that it goes over a 370mm X 30mm rotor. And it is painted blue. It's obvious when you look on the back of the caliper in raised letters on the casting it say "370/380".

(These same calipers are used on the M3/M4 over 380mm rotors because the caliper points are 5mm further from the center. NO, you can mount 380mm rotors on an F3x.)

These larger blue calipers over 370x30 rotors are sold as an "M Sport Brakes" option for ~$600 on the sticker. If you enter the VIN into the mdecoder website, it will have a line item that says:

S2NHA M SPORT BRAKES

Now, the smaller front caliper, "standard brakes", for the F3x 335i/340i is also a Brembo 4-piston unit, but it goes over the smaller 340mm X 30mm rotor. And it is painted grey to distinguish it from the blue "M Sport" brakes. On the back of the caliper casting in raised lettering it says "340".

Entering the VIN into the mdecoder website does not show a line item code for these "standard brakes", but in other locations I have seen them referred to as P337A. In some documentation, BMW refers to P337A as a model of "M Sport" brakes. I believe this gets proliferated down to some parts descriptions.

I believe that the S2NHA and P337A are coded the same in the brake front/rear bias also. That may be another reason that they are both referred to as "M Sport".

Just when that all may have begun to make sense, if you had say a 328i and ordered M Sport brakes you would not receive the same components. Mdecoder might list S2NHA and your brakes would be blue, but the front blue calipers would actually be over 340mm X 30mm rotors.

So TireRack or any other retailer would be correct in selling 340mm rotors and referring to them as M Sport Brake rotors- if they were meant to fit on a 328i.

The key to understanding F3x brakes is that the rotor sizes are all unique to a particular caliper, even if those calipers look similar or have similar names. So never purchase by name. Always purchase by the brake's rotor size. I have complained to some retailers that they do not include the rotor size in their descriptions so sometimes it is impossible to tell if the part is correct or not.

Fronts rotors can be 370x30, 340x30, 330x24, 312x24
Rears rotors can be 345x24, 330x20, 300x20

Hope this is helpful to someone!

+1 with super detailed

I for one when looking for brakes for my 428i GC... is to type in the box retailer provided that my car is 435i because my brakes is 4 pot grey 340mm front and single piston 330mm rear.

If I type 428i GC... they give me the most basic brakes BMW offer which is 330x24 and 300x20.

Total cluster F.

[johnung]

Originally Posted by Gen13 F36

+1 with super detailed

I for one when looking for brakes for my 428i GC... is to type in the box retailer provided that my car is 435i because my brakes is 4 pot grey 340mm front and single piston 330mm rear.

If I type 428i GC... they give me the most basic brakes BMW offer which is 330x24 and 300x20.

Total cluster F.

Since the F36 GC (Gran Coupe 5-door hatchback) was introduced a little later, it is often not added like it should be to the compatibility lists. When I've tried to help out a GC owner with an aftermarket shock, spring or brake recommendation, it can quickly become a Sherlock Holmes investigation as to whether an aftermarket part number should fit.

Like the F31 Wagon owners, the F36 Gran Coupe owners have their own niche. It's nice to have the characteristics of a sports sedan in your daily driver when you still need the features of a family toting vehicle.