The Secret Life Of A Hayes V-series Rotor

We take a closer look at how a Hayes V-series rotor begins life as a massive roll of steel, and becomes the finished product that their new Prime brake system uses.

The Secret Life series lets you look beyond the packaging and flash to see what it takes to bring to life the products that we use.

  • The stainless steel is purchased in a large continuous roll; like toilet paper, but without the perforations or 2 ply thickness.
  • The stamping press straightens the strip through rollers, then stamps out the shape. It’s a progressive die, meaning the rotor geometry is created by stamping the part multiple times with various dies. One hit removes material in the center for the hub, one punches out the cooling holes in the rub area, one creates the ‘spokes’ in the center, etc. The last hit is the one that punches the rotor out of the strip. Like making cut-out cookies, the rotor goes on for further processing and the rest of the strip is recycled.

The Hayes V-series rotor in various stages of production. If you thought that making a rotor was a quick and simple process, you thought wrong.

  • Then the critical dimensions of the rotor are machined. Things like the mounting holes and the lobes that locate the hub.
  • After that the rotor is ED coated. The whole rotor is essentially painted black. This keeps the “as-stamped” surfaces (those created from the stamping process that do not get machined or ground afterwords) from oxidizing.
  • The stainless steel we use is called martensitic stainless steel. It has very high strength, is heat treatable and machinable, but does not have the best corrosion resistance, compared to other grades of stainless steel. The ground and machined surfaces of the rotor have a very smooth surface finish, almost mirror-like, which keeps oxidation (rust) to a minimum, but the rougher as-stamped surfaces will begin to show red rust over time if not protected as the high amounts of iron in the stainless begin to oxidize or rust.
  • The rotors are ground to the proper thickness and flatness. This removes the ED coating off the part, except for the as-stamped edges.

Two pieces become one when the steel braking surface is riveted to the aluminum carrier

  • Then the rub area of the rotor is heat treated to increase hardness and reduce the wear rate. The heat treat is a special, proprietary process that maintains the flatness of the rotor.
  • The rotors are then ready for use. Bicycles are of course lighter than most all other vehicles with disc brakes, but in the ultra weight conscious bike industry, the mass of the rotor is minimized creating extreme usage conditions that match or exceed the harshest motor racing environments.
  • Temperatures reach over 1000 deg F in the rub area, but remain much cooler at the hub. This creates a thermal stress as the rub area expands with heat, but the hub area doesn’t. The rotor needs to be able to allow this expansion, but still remain flat and return to its original form when cool. All this in addition to the brake torque loads.

After a lot of work, this is the finished product. This V-series floating rotor is used on the new Hayes Prime brakes and is available in 140, 160, 180, 203, 224 mm

A brake rotor is a simple looking part, but presents a formidable design challenge.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: