Hella 355118782 Vented Brake Rotor 350mm

This is the Hella 355118782, a vented one-piece disc brake rotor built to replace a worn or warped rotor on the axle where it fits. It measures 350mm across the outside diameter, runs 20mm at nominal thickness, and stands 59mm tall from the mounting face to the friction surface. The center hub bore is 79mm and the mounting pattern is 7 x 120mm. If those numbers match what's on your vehicle right now, you're in the right place.

Rotors are a wear item. Every time you hit the brakes, the pads clamp down on this friction surface and shave off a little material along with a lot of heat. Over enough miles that surface thins out, and if it heats and cools unevenly it can warp, which is what you feel as that pulsing in the pedal at highway speed. Once a rotor drops below its minimum thickness or develops a lip you can catch a fingernail on, it's done. You don't resurface your way out of that. You replace it.

What you get here is a vented casting, not a solid blank. The two friction faces are separated by internal vanes that pull air through the middle as the rotor spins. That matters more than people think. Heat is the enemy of braking. A vented rotor sheds it faster, which keeps the pad compound in its happy range and cuts down on brake fade on a long downhill or during repeated hard stops. The one-piece design means the hat and the friction ring are cast as a single unit, so there's nothing to work loose and the whole thing indexes cleanly onto the hub.

The gray cast iron gets a zinc coating, and that's a detail worth caring about. Bare cast iron starts flash-rusting the moment it's exposed to humidity. You've seen it on a car that sat a week in the rain, that orange film on the rotor face. The zinc coating protects the hat, the vanes, and the areas the pads don't sweep, so the rotor looks clean behind an open wheel and, more importantly, resists the kind of corrosion that eats into a rotor from the edges over a few winters of road salt. The pads still wipe the friction band clean every drive.

A note on quantity. This part number is a single rotor. Brakes work in pairs across an axle, so if you're replacing one side you should almost always do both at the same time. A fresh rotor on one corner and a grooved, thinned rotor on the other gives you uneven braking, and that's the last thing you want when you need to stop straight. Order two.

Fresh rotors call for fresh pads, and they should go in together. Putting used pads with their old wear pattern onto a new smooth rotor keeps them from ever seating fully, so you lose bite and you can glaze the pad. Match new pads to this rotor, and use pads rated for your vehicle's weight and how you drive it.

Installation is straightforward if you've done a brake job before. Pull the caliper and bracket, slide off the old rotor (a couple of taps with a dead-blow usually frees a stuck one), and clean the hub face down to bare metal so the new rotor sits dead flat. Any rust or crud on the hub throws off runout and brings back that pulsing you were trying to fix. Wipe the protective film off the friction faces with brake cleaner, hang the new rotor, torque the caliper bracket to spec, and bed the brakes in with a series of moderate stops before you lean on them hard.

One thing we'll always tell you straight: confirm the fitment before you buy. The 350mm diameter, 20mm thickness, 79mm hub, and 7 x 120mm pattern are the numbers that decide whether this rotor bolts on. Measure your old rotor or check your part number against these specs. If they line up, this is a clean, corrosion-protected replacement that'll bring your braking back to where it should be. If they don't, it's the wrong part, and we'd rather you know that now.