[Jab3r]

Hi Everyone,

I am sorry if this has been asked before but I’m hoping someone can help me with understand what brakes to purchase for my car.

I’m looking to upgrade from the standard braking system to the M sport blue system on my car. Looking at sizes seems a mine field and I’m unsure if the 340’s are the right ones to get or 370mm on front and 345 on back is right that I’ve read people have.
Can anyone tell me what sizes I need to get ?

It’s my first BMW that I got a week ago so my knowledge on them is small .

Any help would be massively appreciated.

[Syfres]

I have the m performance brakes on my 328i. The only difference is mine are slotted and dimpled. 370mm in front and I believe 340mm rotors in the rear. Hope that helps

[Jab3r]

Originally Posted by Syfres

I have the m performance brakes on my 328i. The only difference is mine are slotted and dimpled. 370mm in front and I believe 340mm rotors in the rear. Hope that helps

Thank you !

[Syfres]

Originally Posted by Jab3r

Thank you !

Youre very welcome!!

[alohasurftoad]

345x30 and 345x24 are for 4cyl m-sport or 6cyl base
370x30 and 345x24 are m-performance for F3/4 or F80 base

[johnung]

There is a lot of confusion about F3x brakes. Mostly caused by BMW in their terminology both internal and Marketing.

The most important thing to understand is that each specific size rotor matches a specific caliper. You cannot change the size of the rotor without also changing the caliper, and vise versa. It is easy to measure the diameter of a rotor right on the car to tell which caliper you have. See photos.

The M Sport Brakes which were a factory option are always Blue. But they came in two different size combinations depending on the F3x model. So just saying M Sport Brakes tells you that they are Blue, but not which size.

Note: If you have an “M Sport” car that means it has different bumpers, wheels, steering wheel. It does NOT mean that you have M Sport Brakes! M Sport Brakes have their own line item on the factory build sheet, and they are Blue, they are always Blue. Factory code is S2NHA.

M SPORT BRAKES (BLUE)
Front 370mm x 30mm, 4-piston Brembo
Rear 345x24, 2-piston Brembo
OR
Front 340x30, 4-piston Brembo
Rear 345x24, 2-piston Brembo

Front 370mm rotors will NOT fit under 17” BMW wheels. They require at least 18” BMW wheels.

Front 370 & 340 calipers are NOT the same despite looking similar. The 370 casting is actually stretched out by 15mm to accommodate the larger rotor. However the two different calipers do take the exact same brake pad part numbers.

You can tell the two calipers apart by looking at the back where in raised lettering in the casting it will either say “340” or “370/380”

The braking performance of the two calipers is identical. The 370’s are more desirable for tracking because the larger mass of the rotors can handle more heat before brakes fade. The larger 370’s are more desirable aesthetically.

Typical used prices for the Brembo calipers in good condition are:
$550-$650/pair for 370’s
$450-$550/pair for 340’s
$450-$550/pair for rear 345’s

Stock rotors are usually too expensive to ship, but may be worth $50-$150/pair in a local sale. Stock used brake pads are worthless.

To add to the confusion, the 340 caliper is also available in Grey and comes paired with a single piston Bosch caliper, also Grey, over 330mm x 20mm rotors. The factory code is P337A. They are sometimes called M Sport Brakes but they are NOT! Which only adds to the confusion.

UPGRADING FROM F340/R330:

Upgrading the Front 340’s to Front 370’s does nothing for braking performance on the street. It is only for looks. But if you track, brakes will be less prone to fade with Front 370’s.

Upgrading from Rear single-piston Bosch 330’s to Rear dual-piston Brembo 345’s will improve braking performance. The F340/R330 combination nose dives the car under heavy braking. The F340/R345 combination when standing on the brake pedal the car will squat much more controllably. So if you have Grey Front 340’s it is definitely worth upgrading the rears to Brembo 345’s.

The 345x24 rotors come in two different emergency brake sizes. You MUST purchase rotors that fit the e-brake on your car. No, you can change that, the parts are way too expensive. The e-brake is like an old fashioned drum brake that is located inside the machined out rotor hat. Older e-brakes have a 160mm diameter, newer are 185mm. See photo to easily look up which size of e-brake your car has.

UPGRADING TO F340/R330
This is a very desirable upgrade if your car has a smaller brake combination such as F312/R300 or F330/Rear300. It’s pretty inexpensive because the used Grey 340 calipers sell at the lower end of the range and the rear 330 calipers are worth about $100/pair.

However, I have never seen a stock or aftermarket Rear 330x20 rotor that comes machined for the smaller 160mm e-brake. So you can only do this upgrade to F340/R330, if your stock e-brake from the factory is 185mm.

I highly recommend G2USA Caliper Paint if you end up with calipers of mismatched colors. Do careful surface preparation and brush G2 on the calipers on or off the car. As it dries brush marks disappear as the surface evens out to a sprayed on look. It’s required to only paint with air temperature in the specified range or the paint will glob on the brush and it will be a mess. G2 is a hard epoxy paint that’s difficult to chip and doesn’t fade like other caliper paints. Looks fresh years later. See photo.

The F3x has many brake combinations, listed in order of brake performance:
F370x30/R345x24
F340x30/R345x24
F340x30/R330x20
F330x24/R330x20
F330x24/R300x20
F312x24/R300x20

Hope this helps!

[Jab3r]

Originally Posted by johnung

There is a lot of confusion about F3x brakes. Mostly caused by BMW in their terminology both internal and Marketing.

The most important thing to understand is that each specific size rotor matches a specific caliper. You cannot change the size of the rotor without also changing the caliper, and vise versa. It is easy to measure the diameter of a rotor right on the car to tell which caliper you have. See photos.

The M Sport Brakes which were a factory option are always Blue. But they came in two different size combinations depending on the F3x model. So just saying M Sport Brakes tells you that they are Blue, but not which size.

Note: If you have an “M Sport” car that means it has different bumpers, wheels, steering wheel. It does NOT mean that you have M Sport Brakes! M Sport Brakes have their own line item on the factory build sheet, and they are Blue, they are always Blue. Factory code is S2NHA.

M SPORT BRAKES (BLUE)
Front 370mm x 30mm, 4-piston Brembo
Rear 345x24, 2-piston Brembo
OR
Front 340x30, 4-piston Brembo
Rear 345x24, 2-piston Brembo

Front 370mm rotors will NOT fit under 17” BMW wheels. They require at least 18” BMW wheels.

Front 370 & 340 calipers are NOT the same despite looking similar. The 370 casting is actually stretched out by 15mm to accommodate the larger rotor. However the two different calipers do take the exact same brake pad part numbers.

You can tell the two calipers apart by looking at the back where in raised lettering in the casting it will either say “340” or “370/380”

The braking performance of the two calipers is identical. The [...]

Thank you so much for that🙏

[cfm56d7b]

Originally Posted by Jab3r

Hi Everyone,

I am sorry if this has been asked before but I’m hoping someone can help me with understand what brakes to purchase for my car.

I’m looking to upgrade from the standard braking system to the M sport blue system on my car. Looking at sizes seems a mine field and I’m unsure if the 340’s are the right ones to get or 370mm on front and 345 on back is right that I’ve read people have.
Can anyone tell me what sizes I need to get ?

It’s my first BMW that I got a week ago so my knowledge on them is small .

Any help would be massively appreciated.

What size wheels does your car have?

[Jab3r]

Originally Posted by cfm56d7b

What size wheels does your car have?

I have 18 inch wheels on the car

[cfm56d7b]

Originally Posted by Jab3r

I have 18 inch wheels on the car

Are these wheels OEM 400M by any chance? If yes - these wheels will clear M Sport or M Performance brakes.

[Jab3r]

Originally Posted by cfm56d7b

Are these wheels OEM 400M by any chance? If yes - these wheels will clear M Sport or M Performance brakes.

Yeah that’s right , thanks for confirming

[Syfres]

Originally Posted by Jab3r

Yeah that’s right , thanks for confirming

This is my car before I went with m513. They clear the m400 by just enough

[Coops361]

Just did the M Perf upgrade on my F30. Any questions you have specific on the switch let me know! I love them. Huge upgrade over the basic brakes.

[rikuf31]

Originally Posted by johnung

UPGRADING TO F340/R330
This is a very desirable upgrade if your car has a smaller brake combination such as F312/R300 or F330/Rear300. It’s pretty inexpensive because the used Grey 340 calipers sell at the lower end of the range and the rear 330 calipers are worth about $100/pair.

However, I have never seen a stock or aftermarket Rear 330x20 rotor that comes machined for the smaller 160mm e-brake. So you can only do this upgrade to F340/R330, if your stock e-brake from the factory is 185mm.

Can anyone help me with coding for this brake upgrade?
I have sourced the parts but they are not installed yet.

[johnung]

Originally Posted by rikuf31

Can anyone help me with coding for this brake upgrade?
I have sourced the parts but they are not installed yet.

Which sizes were you able to get?
Front 370mm, Rear 345mm?
or F340, R345?
or F340, R330?

You should be able to find a local independent shop on BimmerShops website who can code for you. It’s supposed to be simple.

Here’s a great video about the ISTA procedure to get the air out of the system.

[rikuf31]

I got F340/R330. Currentyle have F312/R300 with 185mm handbrake drums.

[_ObiJon]

If you can't find a local shop, the ProTool app with an OBD dongle can do the coding. There's also Facebook support group if you have questions.

[SD Convert]

Originally Posted by johnung

Front 370 & 340 calipers are NOT the same despite looking similar.
...
The braking performance of the two calipers is identical.

This doesn't seem correct. While it's obvious that the clamping force of the two calipers is the same (same pistons and pads), the fact that the 370mm rotor moves that clamping force 15mm away from the hub provides that clamping force with a longer lever, providing about a 9% improved braking force.