Solid and vented discs are common terms seen when you’re looking at replacing your brake discs (or are simply researching which bikes or cars have which type). But what is the difference between the two types, and are they interchangeable? Let’s take a look.
Solid discs look as you would expect:
One slightly tarnished, solid disc of metal. Vented discs, on the other hand:
…are more like two discs of metal with ribs inbetween, allowing air to flow through and provide a cooling effect. These are consequently generally much thicker than solid discs.
For the same size rotor, both types will be able to have the same amount of braking force applied to them. The advantage of the vented discs lies in the fact that they are able to shed the heat build-up more quickly than solid discs which leads to a longer period of time before brake fade becomes an issue, which results in more consistent braking.
Many vehicles simply don’t allow for easy swapping between solid and vented discs due to the thickness difference; if you do have the choice, though, there’s no disadvantage to the vented type for road vehicles except perhaps for a slight difference in weight – so unless there’s a significant price difference that should be a fairly straight-forward choice. Both types of disc can be machined if there is a build-up of brake pad material on them, and both can be cross-drilled if that’s your style.
Some cars, like the Ford Escort Mark IIs, can utilise different caliper and caliper bracket setups to allow for vented discs to replace the stock solid ones. If you are doing a vintage car build, it may be worth looking into the brake rotor options if you intend on driving the car hard.