Hella 355119531 Vented Brake Rotor | 328mm 5x120

This is the Hella brake rotor, part number 355119531. It's a vented, one-piece disc cast from gray iron and finished with a zinc coating to hold off surface rust. If you've pulled a wheel and found scoring, a lip you can catch a fingernail on, or a pulsing pedal under braking, this is the kind of part that fixes it.

The numbers matter here, so let's lay them out. The rotor measures 328 millimeters across, that's about 12.9 inches. Overall height is 73 millimeters, thickness through the friction faces is 28 millimeters, and the center hub bore is 75 millimeters. The wheel bolt pattern is 5 x 120, five studs on a 120 millimeter circle. That combination shows up on a lot of European performance sedans and SUVs. Before you order, match those figures and the OE part number against your own car. A rotor that's a hair off on diameter or hub bore won't sit right, and you'll know it the first time you touch the brakes.

Vented is the important word. A vented rotor has cooling vanes cast between the two friction faces, so air pulls through the disc as the wheel turns. That moves heat out of the braking surface fast, which is exactly what you want on a heavier car or anything that sees spirited driving or long downhill grades. Heat is what warps rotors and fades pads, so getting it out of the disc keeps your stopping distances honest.

The one-piece gray cast iron construction is the traditional, proven approach. It's easy to bed, quiet, and machinable if you ever need to true it down the road, though at 28 millimeters you've got sensible material to work with. The zinc coating on the hat and edges is a nice touch. It keeps the non-friction areas from blooming orange the first week you drive in the rain, so the wheel and hub stay clean and the rotor comes off easier next time.

A couple of install notes from experience. Replace rotors as an axle set, both sides, even if only one looks bad. Braking is a balance job and a fresh disc against a worn one pulls the car. Fit new pads at the same time and bed them properly, a series of firm slowdowns from moderate speed without coming to a full stop, so the pad material transfers evenly onto the new surface. Clean the hub face down to bare metal before the rotor goes on, torque the caliper bracket and any retaining screw to spec, and you're done. This one's listed and sold as a single rotor, so order two if you're doing the pair, which you should be.

How do you know it's time? A few signs. A vibration or shudder through the pedal or steering wheel under braking usually means the rotor has warped or worn unevenly. A deep groove or a pronounced edge lip means the friction surface is past its service life. And if the rotor has worn below its minimum thickness, stamped into the hat by the manufacturer, it has to be replaced, not resurfaced. Rotors are a wear item, same as pads, so there's no shame in them wearing out. Catching it early saves the caliper and keeps the car stopping straight.

On corrosion, the zinc coating earns its keep in real driving. Bare cast iron starts flashing rust within hours of getting wet, and while the friction ring wipes clean every time you brake, the hat and the vents don't. Left bare, that rust creeps and makes the next rotor swap a fight. The coating keeps those areas cleaner and buys you an easier service down the line. It's a small thing that tells you the part was built to live outside, not just look good in the box.

Bottom line, this is a straightforward, correctly specified replacement disc for a 5 x 120 pattern with a 75 millimeter hub and a 328 millimeter vented rotor. Confirm those dimensions against your vehicle, buy them in pairs, throw fresh pads at it, and you've got a solid brake job. If you're not sure whether the size matches your car, send us the year, make, and model or your OE rotor number and we'll help you check before you order.