# Ceramic or Iron: Looking After Your Brakes on a Long Descent

How Porsche's iron and carbon-ceramic PCCB brakes behave on a long alpine descent, why fluid matters more than discs, and how to drive down a pass.

Source: https://porschetrails.com/blog/2026-10-03-ceramic-or-iron-brakes-on-long-descents/

Coming down the [Stelvio](/trails/stelvio-pass/) means losing about 1,800 m of height through dozens of hairpins. All of that energy goes into the brakes as heat, unless you find somewhere else to put it. Here is what happens, and what difference yellow calipers make.

## Where brakes actually fail

On a road descent, brake fade almost always comes from one of two things.

- **Fluid boiling.** Brake fluid absorbs water over time, and wet fluid boils at a much lower temperature than fresh. Vapour in the lines compresses, and the pedal goes long and soft. This is the common one.
- **Pad fade.** Pads pushed beyond their working temperature lose grip, and the pedal stays firm while the car stops less well.

The discs themselves are rarely the limit on the road. That is why the first piece of advice is the same for every car: change the fluid before a mountain trip. Porsche specifies a change every two years in any case.

## Iron discs

The standard brakes on a 911 or 718 are large, drilled and ventilated iron discs with fixed multi-piston calipers. They are designed with circuit use in mind and are more than adequate for any pass. Their limits on a long descent are heat soak into the fluid and, eventually, the pads. Driven sensibly, you will reach neither.

## Carbon-ceramic (PCCB)

Porsche Ceramic Composite Brakes were introduced in 2001 on the 996 GT2 and are recognisable by their yellow calipers. The discs are made of a carbon-fibre-reinforced ceramic. They are roughly half the weight of iron discs of the same size, they barely fade and they produce little dust.

On a descent, what you notice is consistency: the pedal feels the same at the bottom as at the top. What ceramics do not do is protect the fluid from old age, so the advice about fresh fluid still applies. They are also expensive to replace, and the edges can be chipped by careless wheel removal, so tell any tyre fitter what they are.

## How to come down a pass

- **Use the gears.** Hold second or third and let engine braking do the steady work. With PDK, use manual mode so the gearbox does not shift up.
- **Brake firmly, then release.** Short, firm applications before each corner, with the brakes off in between, keep temperatures lower than a constant light drag.
- **Do not park on hot brakes with your foot on the pedal.** At the bottom, roll gently for a few minutes if you can.
- **If the pedal goes soft, stop** somewhere safe and let everything cool.

## Electric and hybrid cars

A [Taycan](/models/taycan/) changes the picture. Most of the retardation on a descent comes from the motors acting as generators, which puts energy back into the battery and leaves the friction brakes almost unused. A long pass can add a useful amount of range. The friction brakes still need exercising now and then, since discs that are never used corrode.

For the full pre-trip checklist, see the [road trip preparation guide](/guides/road-trip-preparation/), and for track use, the [track day guide](/guides/track-day-modifications/).