RS246.com Forum :: The World's #1 Audi R, S and RS Enthusiast Community

Hi Guys

Has anyone tried to fit 420mm discs on the front of a b7 rs4 ?

I currently run 20" wheels ..

Here is a pic of my car for the hell of it

Have a look on insta for kimboyrs4 he’s fitted 410s


Sent from my iPhone using Tapatalk

He had to machine down the Caliper to get it to fit under the wheel. Also some wheels won’t allow the figment. Depends on the profile.


Sent from my iPhone using Tapatalk

OT. Have you got laminex on your headlights ??

Go big or go home!!!

How much heavier are 420mm Vs OEM, can't imagine it does much for the handling

420 ceramics are lighter then oem 365 steel

Here’s the thing, if your planning on running 420’s what are you doing to upgrade the master cylinder or brake booster?

If it’s just for looks then fine but you’ll never get the full potential of the disc as the cylinder can’t pump enough fluid effectively.

If it did you’d be over braking on the fronts.


Easiest way to see if they fit is to use a cardboard cutout and centre it on your hub.


Sent from my iPhone using Tapatalk

It has nothing to do with the discs, is the area of the pistons on the caliper. Oem is 8-piston calipers. Brembo caliper for the 400mm and the 420mm is only 6-piston but a little bigger area so the brake pedal travel is about the same. If you choose the bigger Alcons calipers for the 420mm disc they are 8-piston and the pedal travel should be a little longer for the same braking power.

Softishman wrote:It has nothing to do with the discs, is the area of the pistons on the caliper. Oem is 8-piston calipers. Brembo caliper for the 400mm and the 420mm is only 6-piston but a little bigger area so the brake pedal travel is about the same. If you choose the bigger Alcons calipers for the 420mm disc they are 8-piston and the pedal travel should be a little longer for the same braking power.

I think you misunderstood me.


Sent from my iPhone using Tapatalk

I don’t think so.