Hella Pagid 355113932 Rear Rotor 300mm | Audi A4 Q5

The Hella Pagid 355113932 is a rear disc brake rotor built for the Audi B8 family, the A4, A5, Q5, A6 and allroad across most of the 2008 to 2017 run. It's a 300mm solid disc, 12mm thick, cast from gray iron and finished with a zinc coating that keeps the hat and the unswept edges from rusting orange the first week you park it. If you're replacing worn rears, this is a clean OEM-style fit.

Fitment comes down to the numbers. The bolt pattern is 6 by 112mm and the center hub bore is 68mm, which lines up with the factory rear hubs on those cars. Outside diameter is 300mm, nominal thickness is 12mm, and the overall height from the friction face to the back of the hat is 36.2mm. Those are the dimensions that matter when you're matching a rear rotor. Get them right and the caliper bracket, the pads, and the wheel all sit where they should.

One thing to know before you order. This is a single rotor, not a pair. A car has two rear discs, so you'll want two of these to do the axle properly. And you should always replace rotors in axle sets. Mixing a fresh disc with a worn one on the same axle gives you uneven braking and a pedal that never feels quite settled.

The zinc coating is the part people underrate. Bare cast iron flash-rusts anywhere the pad doesn't sweep, so the hat and the outer edge go rusty and ugly fast, especially through a salted winter. The zinc finish holds that off. The friction ring still wears in normally under the pads, but the cosmetic areas stay clean behind an open wheel. Gray cast iron is the standard material for a reason. It sheds heat predictably and machines true.

This is a solid rotor, not a vented one, which is exactly right for a rear axle on these cars. The rear brakes on an A4 or Q5 do less work than the fronts, so the factory runs a thinner solid disc back there. Don't let the solid design worry you. It's the correct spec for the position, not a downgrade.

If you're doing this job at home, it's a straightforward afternoon. Pull the caliper and bracket, swap the disc, clean the hub face so the new rotor seats flat, and torque everything to spec. New pads are smart if the old ones are past half life. Bed the brakes in gently for the first few miles, a series of moderate stops from moderate speed, and you'll get quiet, even braking that lasts.

How do you know the rears are due? Pulsing through the pedal or a light shimmy under braking usually means the discs have worn unevenly or warped from heat. A lip you can catch with a fingernail at the outer edge means the friction surface has worn down. Deep scoring, blue heat spots, or a thickness below the manufacturer minimum stamped on the hat all mean it's time. Rear rotors on these Audis tend to outlast a set or two of pads, so if you're on your second or third pad change back there, measuring the disc is worth the two minutes.

Pair it with a quality set of rear pads and fresh hardware. The rotor and pad wear together, so putting old glazed pads onto a fresh disc undoes half the benefit. If the car has an electronic parking brake actuating on the rear calipers, remember to put the system into service mode before you retract the pistons. Skip that step and you can damage the actuator.

Every rotor ships with the full Hella manufacturer warranty behind it. It's the same braking hardware that supplies plenty of original-equipment programs, so you're not gambling on an unknown casting. Order two for the axle, grab pads if you need them, and you've got everything for a proper rear brake refresh.