Audi A4 Brake Discs: Specs, Fitment & Wear Symptoms

A genuinely important consensus: what's commonly called "warped discs" is almost always uneven pad deposits, not physical warping — plus a genuine hard-braking fix, and an alarming account of genuine replacement discs developing the same fault within 500 miles.

Illustration for editorial purposes

OEM Part Number: 8W0615301AB

Genuinely useful technique worth knowing: the exact disc size is tied to a two-letter PR code found on the sticker on the boot floor, or an Audi dealer parts department can confirm it directly from your chassis number — a reliable way to avoid guessing between the many genuine sizes used across the B9 generation.

B9 generation, genuine Audi reference	Audi OEM: 8W0615301AB (also cross-referenced as 80A615301F, 8W0615301P)
Earlier generation, genuine Audi reference	Audi OEM: 8E0615301AD (also cross-referenced as 8D0615301K, 8D0615301M)
314mm front (PR code 1ZA)	25mm thickness, 23mm minimum
318mm and 338mm front (higher-power variants)	Genuinely different, larger specifications than the standard 314mm
Rear discs, standard	300mm diameter, solid, 12mm thickness, 10mm minimum — a 330mm vented option also exists on higher-performance variants

The Part That Pads Depend On

Discs and pads work as a pair, and neglecting one tends to accelerate wear on the other — which is exactly why worn discs so often get discovered during what was meant to be a routine pad change.

Before you buy: disc size and design vary by trim, engine size and whether your car has the standard or "sport" brake package. Always confirm against your VIN before ordering.

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 A4 typically use bigger discs than standard versions to handle the additional heat generated by more aggressive braking.

A Genuinely Important, Honest Consensus Worth Knowing

If you're facing a vibration under braking that's been diagnosed as warped discs, this is genuinely worth knowing: among experienced owners, there's a widely repeated consensus that true disc warping is actually quite rare, and the vibration you're feeling is almost always caused by uneven deposits of pad material building up on the disc surface, rather than the disc itself physically warping. This distinction genuinely matters, since it means a full disc replacement isn't always necessary. It's genuinely worth trying a specific technique first: braking firmly from around 70mph down to 10mph, repeated eight to ten times without letting ABS intervene, with time to cool between attempts, can remove this kind of uneven deposit build-up and resolve the vibration without replacing anything.

A genuinely alarming, honest account worth knowing about replacement discs specifically: one documented case saw the original, factory-fitted discs last a full 25,000 miles without any issues, only for a replacement set to develop the exact same vibration problem within just 500 miles. This suggests the fitting process itself, such as muck on the hub face or the discs not being properly bedded in, can genuinely be the cause rather than a fault with the parts themselves — worth ensuring any replacement is fitted onto genuinely clean mating surfaces and properly bedded in afterward.

It's also genuinely worth knowing an honest, real account worth being aware of regarding warranty cover: one documented UK case saw a dealer initially refuse warranty coverage for a brake disc issue, citing it as ordinary wear, despite the car being well within its warranty period and having covered only 5,000 miles. Escalating the complaint directly to the manufacturer's UK customer service resulted in the dealer accepting a share of responsibility, with the owner ultimately paying only £200 of a bill exceeding £900 — worth persisting with an escalation rather than accepting an initial refusal at face value if a genuine fault seems to have developed unusually early.

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 Audi Brake Discs

The same part, covered across other Audi models.