BMW 4 Series Brake Discs: Specs, Fitment & Wear Symptoms
On the 4 Series, what's commonly called "warped discs" is genuinely almost always uneven pad deposits, since cast iron is genuinely hard to warp.
Illustration for editorial purposes
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OEM Part Number: 34118848417 (genuine front disc — confirm via VIN) — aftermarket front discs Brembo 09.C114.11 / Bosch 0 986 479 A18
| Front brake discs (aftermarket) | Brembo 09.C114.11 (300 x 22 mm, vented, 5 holes, coated, high-carbon, min 20.4 mm); Bosch 0 986 479 A18 (300 x 22 mm, vented, 5 holes, coated, high-carbon, min 20.5 mm); ATE 24.0122-0278.1 (300 x 22 mm, vented, 5 holes, coated, high-carbon, min 20.4 mm); Brembo 09.B337.21 (312 x 24 mm, vented, 5 holes, coated, high-carbon, min 22.4 mm); Bosch 0 986 479 381 (312 x 23.9 mm, vented, 5 holes, coated, high-carbon, min 22.4 mm); ATE 24.0124-0203.1 (312 x 24 mm, vented, 5 holes, coated, high-carbon, min 22.4 mm); TRW DF4807S (312 x 24 mm, vented, 5 holes, black painted, high-carbon); Brembo 09.C398.13 (340 x 30 mm, two-piece vented with aluminium hub, 5 holes, coated, high-carbon, drilled and slotted, min 28.4 mm) |
|---|---|
| Disc sizes & variants | Three front sizes, 300 mm, 312 mm and 340 mm. The 300 x 22 mm disc is the base fitment on the 418d and 420i/420d, the 312 x 24 mm disc is the common fitment on the 420d, 425d, 428i and 430d, and the 340 x 30 mm disc is the M Sport brake and 435i/440i fitment. |
| Genuine (OE) numbers quoted | 34118848417 (genuine front disc number for this model — confirm via VIN, as several disc sizes exist) |
| Fitment notes | Minimum thickness is 20.4 mm on the 300 mm disc, 22.4 mm on the 312 mm disc and 28.4 mm on the 340 mm disc; Brembo quotes 120 Nm wheel bolt torque. Brembo 09.C114.1X and 09.B337.2X are the drilled versions of the 300 mm and 312 mm discs, ATE 24.0324-0203.1 is the PowerDisc 312 mm, and febi 39111 (300 mm), 30541 (312 mm) and 105724 (340 mm, drilled) are the budget coated options. |
BMW 4 Series Brake Discs: The Part That Pads Depend On
On the BMW 4 Series, wear on one of this pair accelerates wear on the other, so a pad change booked as routine maintenance often turns up discs that have quietly deteriorated alongside them.
BMW 4 Series Brake Discs: Watch: Replacing It
4 Series pads and rotors; generation/axle not stated in title (F32 likely); alt https://www.youtube.com/watch?v=Y0sLm-FE8wY (BMW Brembo Brakes front pads F32 F30 428i 2013-2020)
BMW 4 Series Brake Discs: What They Do
Brake discs provide the surface the brake pads clamp against to slow the car, converting momentum into heat through friction. Larger, sportier trims of the 4 Series typically use bigger discs than standard versions to handle the additional heat generated by more aggressive braking.
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A Genuinely Important, Honest Clarification Worth Knowing — BMW 4 Series Brake Discs
If a vibration under braking has been diagnosed as warped discs, this is genuinely worth knowing: what's commonly described as "warped discs" is, in reality, almost always caused by uneven deposits of pad material on the disc surface, since cast iron itself is genuinely difficult to warp under normal driving conditions.
It's also genuinely worth knowing a useful fix worth trying: thoroughly cleaning the mating surfaces between the wheel hub and the disc, or better still fitting new hubs entirely, has been documented resolving this kind of persistent vibration.
BMW 4 Series Brake Discs: Wear Symptoms, DIY Difficulty & Aftermarket Advice
These are the same regardless of make or model — see our full Brake Discs Guide for warning signs to watch for, confirming fitment against your VIN, and choosing a reliable aftermarket disc.
More BMW Brake Discs
The same part, covered across other BMW models.