B8 vs B8.5 front brake rotors

[razir66]

Anyone have first hand knowledge if B8 & B8.5 have interchangeable front brake rotors or not? On several sites they are listed as 2008-2011 is one type while 2012-2016 is another yet on ECS Tuning site they have one rotor applicable to 2009-2016. I'm assuming they are different but just slightly.

[Smac770]

Assuming you're talking about the B8 A4/A5 320x30mm 1LA/1LB brakes, the changeover date is June 20, 2011. The rotor and carrier bracket used changed on that date.
Before, the rotor is 8K0 615 301 A and the carrier bracket is 8K0 615 125.
After, the rotor is 8R0 615 301 F and the carrier bracket is 4G0 615 125.

[razir66]

Thank you! I wonder why ecstuning advertises a front rotor for MY2009-2016 then.

[Smac770]

No idea. Take for example the ECS page for the front rotors:
https://www.ecstuning.com/Audi-B8_A4.../Rotors/Front/
Looking at the standard rotors, they list a single Zimmerman entry, https://www.ecstuning.com/b-zimmerma...8k0998301akt3/
They don't show the Zimmerman part number, only the claim that they are 8k0998301a equivalent. What is a 8k0998301a? Nothing seems to know. parts.audiusa.com does not acknowledge the part number.

Going to Zimmerman directly, we see they have two separate part numbers, for before and after June '11 build dates. 100.3331.20 for before and 100.3355.20 for after. All the spacial measurements are the same but the after rotors are .2 kg heavier. What's the difference? What changed in Jun '11? Who the f knows.

[razir66]

i just chatted with ecs tuning, they said there is no difference. so odd...

[Smac770]

I emailed Zimmerman back when I was looking at new rotors for my '09 A4 about what's different between their two part numbers. Not surprised I never heard back. And AoA is the poster child for useless when faced with a technical question.

If ECS has sat an actual Audi OE 8K0 615 301 A next to an actual Audi OE 8R0 615 301 F and measured every possible spatial measurement with a micrometer and found zero differences, then ok. But explain to me why Audi carries on still today with two different stock numbers for supposedly identical objects?

[razir66]

Yea, a fellow is selling a complete brake kit and the front rotors are for the 2009-2011 and mine is a 2014, was hoping to buy them but I don’t want to get then and run into some fitment issue. Appreciate your feedback on this.

[ps2cho]

Why bother? Go on FCP get a nice set of Zimmerman Z coat (hands down best rotors available) and a set of Akebono pads and be done with it