S5 upgrade front rotor size

[DisGrnS5]

Apologies if this has already been discussed but I searched the forums and couldn't find a good answer. I would like to increase the front brake rotor size on my B9.5 S5 primarily for aesthetics. Is the stock brake caliper compatible with a larger rotor or would the caliper need to be upgraded too? Are RS5/RS4 stock rotors/calipers bolt-on upgrades for the S5? I seen the Brembo BBK but I would like to keep the set up as OEM-looking as possible.

[choy188]

I'm 99% sure the RS setup is bolt on, I also believe that C8 3.0 and 4M Q7 calipers would fit with the rs5 caliper bracket but I could be mistaken


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[Smac770]

Both the A5/S5 (A5CO) and RS5 (RS5) catalogs have the same Akebono 6-piston fixed 375x36 brake system for the front, same system as the 350x34 variant. The calipers are different part numbers, for S vs RS stickers. The S version and the RS version both list the rev BK pads. The RS version also lists the rev BJ pads; I presume a more aggressive pad. The rotors are different part numbers because standard vs drilled.

So if you want to keep the S logo but move to the larger (drilled or not) rotors, the 375x36 "S" calipers are rev AJ for black or rev AK for red. The "S" rotor is rev AS; the "RS" drilled rotor is rev AM. And the pads are standard rev "BK" or (I assume) aggressive rev "BJ".

[VVG]

Apologies if this has already been discussed but I searched the forums and couldn't find a good answer. I would like to increase the front brake rotor size on my B9.5 S5 primarily for aesthetics. Is the stock brake caliper compatible with a larger rotor or would the caliper need to be upgraded too? Are RS5/RS4 stock rotors/calipers bolt-on upgrades for the S5? I seen the Brembo BBK but I would like to keep the set up as OEM-looking as possible.

Honestly....this is the worst possible place to add weight anywhere on the entire car. Brakes really should be as small as possible to get the job done. Aesthetics should focus on higher quality calipers and colors. Now if you want to increase rotor size and go to ceramics, that is a different matter, as you will drop massive amounts of weight. But that is a serious outlay of cash to do aftermarket. Alternatively, you can even drop your wheel size by an inch (depending on what you have to begin with). This will not only drop weight, but also allow your wheel barrel to appear more "filled" by your stock calipers which I think is the look you are trying to achieve. Keeping unsprung mass as low as possible can dramatically affect your ride quality and steering responsiveness and make for a much more enjoyable driving experience.

The reason there is an aesthetic appeal to larger brakes is that our brains associate this with higher performance, but that just isn't the case here. I look at the Porsches I have owned, and while they all have nice high grade calipers, the actual rotor size is as small as possible for the particular vehicle.

[DisGrnS5]

Honestly....this is the worst possible place to add weight anywhere on the entire car. Brakes really should be as small as possible to get the job done. Aesthetics should focus on higher quality calipers and colors. Now if you want to increase rotor size and go to ceramics, that is a different matter, as you will drop massive amounts of weight. But that is a serious outlay of cash to do aftermarket. Alternatively, you can even drop your wheel size by an inch (depending on what you have to begin with). This will not only drop weight, but also allow your wheel barrel to appear more "filled" by your stock calipers which I think is the look you are trying to achieve. Keeping unsprung mass as low as possible can dramatically affect your ride quality and steering responsiveness and make for a much more enjoyable driving experience.

The reason there is an aesthetic appeal to larger brakes is that our brains associate this with higher performance, but that just isn't the case here. I look at the Porsches I have owned, and while they all have nice high grade calipers, the actual rotor size is as small as possible for the particular vehicle.

Totally get that the car doesn't need the larger brake rotors, this isn't intended to be a pure performance upgrade. The RS5 rotor's weight pretty much the same as the S5 (27.7 lbs v.s. 27.9 lbs). Granted, the RS5 is larger so it will have slightly more rotational inertia, but I imagine that will be negligible. If the rotors are good for the RS5, I imagine they are good enough for the S5. Anyways, if I was trying to get a car with the maximum amount of track performance, I wouldn't have gotten a 2 ton luxury sedan. But to your point, smaller wheels is a great idea and I do intend to remove the stock 20" wheels and install 19" wheels to improve the ride.

[VVG]

Totally get that the car doesn't need the larger brake rotors, this isn't intended to be a pure performance upgrade. The RS5 rotor's weight pretty much the same as the S5 (27.7 lbs v.s. 27.9 lbs). Granted, the RS5 is larger so it will have slightly more rotational inertia, but I imagine that will be negligible. If the rotors are good for the RS5, I imagine they are good enough for the S5. Anyways, if I was trying to get a car with the maximum amount of track performance, I wouldn't have gotten a 2 ton luxury sedan. But to your point, smaller wheels is a great idea and I do intend to remove the stock 20" wheels and install 19" wheels to improve the ride.

True, you will not feel a bit of difference between 27.7 and 27.9 lbs, so if one rotor design is better and allows a larger rotor at the same weight, then great. My comment wasn't meant to be for track performance. Just that lower unsprung weight can help ride quality and steering feel in a car that is still performance oriented.

[DisGrnS5]

Just wanted to update this thread that I switched out the front calipers and rotors with RS5 components. Everything bolted on without any issue. Upgrade to carbotech 1512 brake pads while I was at it. Has a great OEM+ look

[wheeljouster]

Just wanted to update this thread that I switched out the front calipers and rotors with RS5 components. Everything bolted on without any issue. Upgrade to carbotech 1512 brake pads while I was at it. Has a great OEM+ look

Post some pics!

[DisGrnS5]

Didn't take any photos during the install but this is what is looks like now.

IMG_5872 copy.jpg

[RedBeardMcGee]

Didn't take any photos during the install but this is what is looks like now.

IMG_5872 copy.jpg

How much did this cost you? Where did you source the parts? Is there a reason you didn't go with an aftermarket big brake kit?