GT-R R35 Rear 2-Piece Rotor Kits: Stock Brembo vs Alcon Superkit Fit

If your GT-R R35 is running the stock Brembo 4-piston rear calipers, the 380×30 mm Paragon kit is your direct upgrade: same footprint as OEM, no adapter hardware, just better rotors and pads. If you have already fitted an original-generation Alcon Superkit rear, you need the 385×33 mm Paragon kit, which matches that caliper's larger rotor seat and uses a different Winmax pad shape. The two kits are not interchangeable: wrong rotor diameter means the caliper mount geometry won't align, and the pad shapes are specific to their respective calipers.

Spec Comparison

Stock Brembo Rear Kit: Paragon 380×30 mm

Who it's for

This is the kit for any R35 running its factory rear brake setup. The 380 mm diameter and 30 mm thickness match the OEM rotor footprint exactly, so the stock Brembo 4-piston caliper drops straight on without brackets or spacers. That makes it equally appealing whether you want a meaningful track upgrade or just want the visual step-up that a slotted, two-piece floating rotor delivers over the stock drilled unit.

What stands out

The rotor ring is cast from Paragon's CM-250 high carbon alloy iron, which runs cooler and resists cracking better than standard grey iron. Paragon finishes the surface with a CBN (cubic boron nitride) turning process, producing a tighter surface tolerance than conventional grinding. The aluminum hat is machined with an integrated iron sleeve so the OEM electronic parking brake mechanism works without modification. At 24.6 lbs per corner, it sheds 2.4 lbs over the stock Brembo assembly, which is a genuine unsprung weight reduction. The directional 48-vane ventilation and slotted face are meaningful upgrades over the OEM cross-drilled, pillar-vane design, particularly for repeated heavy braking. Replacement rings are sold separately, so when the friction surface eventually wears out, you replace only the ring and not the aluminum hat.

Pad pairing: Winmax PBP691

The included Winmax pad (PBP691) is shaped for the OEM Brembo 4-piston caliper. Several compounds are available for this shape: W4 (avg friction 0.37–0.40 µ, rated to 650°C, sprint/circuit), W5 (0.40–0.43 µ, rated to 750°C, club/circuit and rally), W6.5, and W7. The compound included in the package is not specified in the published listing, so confirm your preferred compound at order. For occasional track days on an otherwise street-driven car, W4 or W5 is the typical starting point; harder compounds want heat before they perform and can feel wooden on a cold morning commute.

Honest trade-offs

This kit does not increase rotor diameter beyond OEM. If your goal is more swept area or a larger thermal mass specifically to outpace what the stock Brembo hardware was designed around, the Alcon Superkit rear caliper (and its matching Paragon rotor) is the route. For everyone else, especially those looking for a cleaner, more durable version of what the factory fitted, this is the right call.

Alcon Superkit Rear Kit: Paragon 385×33 mm

Who it's for

This kit is for R35 owners who have already installed an original-generation Alcon Superkit at the rear. That caliper is a 6-piston monobloc billet unit with a rotor seat designed for a 385×33 mm disc, and nothing in the stock configuration is compatible with it. If you are shopping this kit without already having the Alcon caliper fitted, you are looking at a two-part project: caliper first, then this rotor and pad package.

One important caveat: two generations of the Alcon Superkit exist, and they use different rear rotor diameters. The original-generation Superkit (the one this Paragon kit is sized for) uses 385×33 mm rear discs. The Gen3 Alcon kit uses 380×33 mm rear discs with RC4 forged aluminum calipers, which is a different spec entirely. Confirm which generation you have before ordering.

What stands out

The 385 mm diameter gives a slightly larger swept area than the OEM or stock-Brembo-fit rotor, and the 33 mm thickness adds thermal mass, both of which matter when the rear brakes are doing real work under repeated heavy stops. Paragon offers the replacement rings for this rotor separately as well, so serviceability is on par with the standard-fit kit. The included Winmax pad (PNF4498) is shaped for the Alcon CAR98 / Mono4 caliper and comes in a broader compound range: from W3/P3 for road and occasional track use through W7/R7 for maximum friction and temperature applications. That range suits the Alcon Superkit's wider audience, which Alcon itself positions across both street and race variants.

Honest trade-offs

Several specs for this rotor, including per-assembly weight, hat dimensions, and the rotor-to-hat mounting system, are not published in available documentation. If those details matter for your build (for example, if you are calculating total corner weight or planning a custom hat swap), contact Paragon directly before purchasing. The pad shape (PNF4498) is not interchangeable with the PBP691 used in the OEM Brembo kit, so do not mix components between the two packages.

How to Choose

The decision almost makes itself once you identify your rear caliper.

Stock Brembo 4-piston rear caliper: Order the 380×30 mm Paragon kit. It is a genuine upgrade over the OEM rotor in material, vane design, and surface finish, and it fits without any changes to brackets or hardware. It pairs with Winmax PBP691 pads in your choice of compound.

Original-generation Alcon Superkit rear caliper (6-piston monobloc): Order the 385×33 mm Paragon kit. The rotor dimensions match the caliper's mounting geometry, and the included Winmax PNF4498 pad is shaped for the Alcon Mono4 caliper.

Gen3 Alcon Superkit (RC4 forged calipers, 380×33 mm rear spec): Neither of these packages is confirmed for that application. Check with Alconkits before ordering.

If you are also upgrading the front axle or have already done so, see our guide on GT-R R35 front rotor sizing: 390 mm stock size vs 396 mm Paragon 2-piece for the same caliper-first logic applied to the front end.