[Xens]

13.0F/13.2R for E90 vs. 12.8F/12.9R for E46 M3.

It's not much, but I guess it's something to feel good about.

Sorry, forgot to mention it's for 330, 325 is a bit smaller.

[E90Fleet]

Normal M3 ( euro )
Front: 325x28
Rear: 328x20

M3 CS
Front: 345x28
Rear: 328x20

E90 330i
Front: 330x24
Rear: 336x22

M3 still has thicker front discs and more aggressive pads. Euro version of M3 also has floating discs

One also has to look at the pad surface area. I think the M3 may have more

[Xens]

Originally Posted by E90Fleet

Normal M3 ( euro )
Front: 325x28
Rear: 328x20

M3 CS
Front: 345x28
Rear: 328x20

E90 330i
Front: 330x24
Rear: 336x22

M3 still has thicker front discs and more aggressive pads. Euro version of M3 also has floating discs

One also has to look at the pad surface area. I think the M3 may have more

Good info, I was just lurking bmwusa.com, heh.

What's floating disc btw?

[E90Fleet]

Originally Posted by Xens

Good info, I was just lurking bmwusa.com, heh.

What's floating disc btw?

The piece of the brake that the pad touches and the pice that is attached to the cars hub arnt of one piece of mettal and are connected via special "floating" hubs.

So as heat goes into the brake the one part can expand indipendantly from the other. And you can make each from the optimum type of metal for its work.

[E90Fleet]

From Brembo

Why use a two-piece "floating" disc assembly?
There are several reasons that a two-piece floating disc assembly is of benefit. First, by using an aluminum bell for the hub section of the disc saves a great deal of weight. Since this is both rotating and unsprung, it benefits the acceleration, braking, and handling of the vehicle. Secondly, it is better able to handle the large temperature changes that a brake disc experiences. During severe use, temperature variances become present in a one-piece disc and generally cause warping of the disc. This not only results in vibration of the vehicle, and pulsing of the brake pedal, but also pushes the pistons farther away from the disc. In a two-piece floating disc assembly, the iron disc heats up more uniformly, and the controlled float which is present allows for the differential expansion of the very hot brake disc, and the relatively cool aluminum bell. This allows the disc to be used under severe conditions without having a detrimental effect.

[SRT]

E46 M3s' brakes are cross-drilled, no?

[ward]

OK, but does it stop better??

[ryan330]

Originally Posted by ward

OK, but does it stop better??

I believe the M3 takes about 2.6seconds to get from 100km/h to 0, and the 330 takes about 2.9s, so in short the M3 brakes are better

[Xens]

Yeah, doubt it stops better, just found it surprising that we have bigger discs.

Originally Posted by RR

E46 M3s' brakes are cross-drilled, no?

Yes, if it has the competition package.

[E90Fleet]

Originally Posted by CMD

Yes, if it has the competition package.

All euro ones are aswell

[BMW0]

Yea! Bigger brakes than M3

[Atty]

Anybody ever use ceramics? Since all of these cars stop short enough for me, the benefit would be no brake dust. Just wondering.

BTW - I always think about the problem caused by superior brakes: the '87 Cutlass Ciera Brougham driven by an uninsured dope - and she's on your tail. I spend more time looking through my rear view mirror than anything else under hard braking....seen too many rear-enders. Anybody else feel this way?

[visor]

Ceramic brakes are crazy expensive. Porsche has an option for the 911.
Only problem is they're also quite fragile... make sure you don't wash your car/wheels or drive thru any puddles of water immediately after you get them nice and hot with massive braking, or else cracks = expensive repair.

[ward]

Originally Posted by visor

Ceramic brakes are crazy expensive. Porsche has an option for the 911.
Only problem is they're also quite fragile... make sure you don't wash your car/wheels or drive thru any puddles of water immediately after you get them nice and hot with massive braking, or else cracks = expensive repair.

it's also an option on Boxster, Cayman

I find it very hard to belive that Porsche would put out "fragile" brakes on a production car

also the poster above was probably talking about ceramic compound pads, not rotors, probably another brake dust complainer

[M3NTAL Kev]

The brake size might have to do with the vehicle weight when compared to the e46 M3.

[Robert]

Originally Posted by Atty

Anybody ever use ceramics? Since all of these cars stop short enough for me, the benefit would be no brake dust. Just wondering.

BTW - I always think about the problem caused by superior brakes: the '87 Cutlass Ciera Brougham driven by an uninsured dope - and she's on your tail. I spend more time looking through my rear view mirror than anything else under hard braking....seen too many rear-enders. Anybody else feel this way?

Thought the main benefit of ceramic is resistance to fade during high strain usage of the brakes. I dont track my car so I never feel my brakes fade except one ocassion when I was younger. Going down Lake Arrowhead Mtn at 10pm with no cars on the road and I was attacking the road at decent speed. 3/4 way down the mountain I felt my brakes aren't as responsive anymore. I was young and didn't know "brake fade." until I pulled over at a gas station below the foothills and smelled my pads burning.

[xdrive]

Anyone know why the rear brakes are larger than the front brakes? With all other cars, the front brakes are usually larger...

[NaTuReB0Y]

Originally Posted by xdrive

Anyone know why the rear brakes are larger than the front brakes? With all other cars, the front brakes are usually larger...

My guess is that...most other cars....
the front weigh a lot more; therefore, bigger brakes in front.

[visor]

even for a 50/50 wt distribution, they should be the same size

my guess is because the rear brakes now are used more in the e90 due to dsc+, ie. hill hold, dtc, electronic brake diff (simulated limited slip) and also due to greater power to the wheels.

[ward]

you're both pretty much incorrect on the sizing issue

the fronts are larger because as you brake the weight transfers forward enabling the fronts to use more brake force (front gets heavy rears get light as you brake) than the rears.

the rear disks on our cars have the parking brake drum built into the center hub, plus I'd assume the crazy DSC features require having larger brakes than the car would otherwise need.

Also I'm pretty sure the car senses how you're stopping and trys to brake more with the rears when it's safe to help even out pad wear from front to back (people with older auto tranny cars should remember replacing fronts 2-3 times before needing to replace the rears)


the fronts should be bigger

[visor]

Originally Posted by ward

you're both pretty much incorrect on the sizing issue

the fronts are larger because as you brake the weight transfers forward enabling the fronts to use more brake force (front gets heavy rears get light as you brake) than the rears.

the rear disks on our cars have the parking brake drum built into the center hub, plus I'd assume the crazy DSC features require having larger brakes than the car would otherwise need.

Also I'm pretty sure the car senses how you're stopping and trys to brake more with the rears when it's safe to help even out pad wear from front to back (people with older auto tranny cars should remember replacing fronts 2-3 times before needing to replace the rears)


the fronts should be bigger

1. first you start off by saying the fronts are larger, then you end up saying the fronts should be bigger. so which is it?

2. for the e46 (and most cars that I can think of offhand), the fronts are bigger than the rears, while this is reversed for the e90. we're trying to understand/postulate why the BMW engineers did this for the e90. we know that under heavy braking the wt transfers to the front causing more braking forces needed for the front brakes, but why then did BMW go larger rear brakes than the fronts?