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Carbon-Ceramic Rotor Reverse Engineering

We can develop a carbon-ceramic replacement for your original steel brake rotor, even when fitment data is unavailable. We use the original rotor’s dimensions to match its geometry.

There are three ways to get the dimensions we need:

  • Measure your steel rotor using the guide below.
  • Arrange a local 3D scan. Contact us first to agree on the file requirements.
  • Ask us to buy a reference rotor. Its cost is included in your project quote.

We review the dimensions and confirm fitment before production.

What you need

  • A precision caliper, preferably digital.
  • A tape measure or long ruler for the rotor diameter.
  • A rigid, straight bar long enough to bridge the rotor without bending.
  • A phone or camera. A helper makes recording easier.

Record each measurement on video, or take a clear photo. Show the tool’s contact points and its reading so our engineers can check your measurements.

Watch the measurement video

Open on YouTube

Measure your rotor

Use millimetres. Record front and rear rotors separately. The numbers in the photos are examples, not dimensions for your vehicle.

Click a photo to see it full size.

1. Overall diameter

From the back of the rotor, measure from one outer edge to the other through the centre.

Tape measure spanning the full diameter on the back of the rotor
Another view Another view of the diameter measurement

2. Rotor thickness

Measure between the two braking faces with the caliper. Show where the jaws touch and any raised wear lip.

Caliper jaws positioned on both friction faces to measure rotor thickness
Another view Another side view of the rotor thickness measurement

3. Friction ring width

From the back, measure the width of the braking surface from its inner edge to its outer edge.

Caliper measuring the radial width of the friction ring

4. Center bore diameter

Use the inside jaws of the caliper to measure the central opening in the rotor hat.

Caliper inside jaws measuring the centre opening of the rotor hat

5. Mounting hole diameter

From the front, measure the inside diameter of a mounting hole in the rotor hat. Also record the number of mounting holes.

Caliper measuring the inside diameter of a mounting hole

6. Bolt pattern and spacing

Record the bolt pattern if known. Measure the mounting-hole spacing as shown, with the holes and contact points visible in your photo. Our engineers use this to check the pitch circle diameter (PCD).

Hole-to-hole spacing is not the PCD itself. The guide’s 5 × 108 mm pattern is an example only.

Caliper checking the distance between mounting holes on the rotor hat

7. Inner height

Work from the back of the rotor. Use the straight bar as a reference, then subtract its thickness from the height reading.

  1. Place the bar across the back of the rotor as shown below.
  2. Measure the bar thickness. Record this as A.
  3. Measure from the inner rotor face to the top of the bar. Record this as B.
  4. Calculate the inner height: B − A.
Reference bar and caliper positioned across the back of the rotor
Measuring from the back.
Rigid reference bar bridging the back of the rotor
The bar must stay straight.

Example: A = 0.88 mm, B = 36.31 mm.
Inner height = 36.31 − 0.88 = 35.43 mm.

See photos of readings A and B
Example caliper reading for reference bar thickness A: 0.88 millimetres
A — bar thickness.
Height reading B measured from the inner rotor face using the bar
B — height reading.

Send your own A and B readings, along with photos of the setup.

Example project: Audi A3 with TT RS brakes

A customer asked us for a carbon-ceramic conversion for his 2015 Audi A3. He had already retrofitted the brakes from a 2012 TT RS — stock TT RS calipers, steel rotors and pads.

Front wheel of the Audi A3 with a yellow RS caliper and the original steel rotor visible through the spokes
As it arrived: TT RS calipers on the original steel rotors.

That retrofit needs a caliper bracket to mount the larger caliper to the factory A3 steering knuckle, so the rotor can end up sitting differently than it would on a TT RS.

Our factory could have manufactured the brackets for him, but that route carries a risk of dimensional error. We advised him instead to measure the inner height of his own steel rotor — the method least prone to mistakes, because it describes the rotor exactly where it sits on his car. He sent us the video below.

The customer’s own measurement video.

What we produced

Using that inner height, we made a pair of front carbon-ceramic rotors, 370 × 32 mm, as a direct replacement for the TT RS steel rotors.

Pair of 370 by 32 millimetre carbon-ceramic front rotors with black hats, supplied with a set of brake pads
The finished front pair, supplied with pads.

Final result

The customer fitted the rotors to the front axle himself. They mate to the TT RS caliper with correct pad alignment and clearance — fitment was confirmed on the car with no rework.

Carbon-ceramic rotor mounted on the front hub next to the yellow Audi RS caliper
Mounted on the front steering knuckle.
Side view of the installed rotor with the TT RS caliper in place over the friction ring
Caliper seated over the friction ring.
Close-up of the rotor hat bobbins and the clearance to the caliper body
Clearance at the rotor hat.

Your project follows the same route: send the measurements, we confirm the geometry, then we build the rotors to it.

Send your measurements

Include:

  • Your vehicle’s make, model, year and brake option.
  • Front or rear axle, and the original rotor part number if known.
  • Your measurements and photos, video or a link to scan files.

Email forzaccb@forzaaa.com. We’ll review the information and confirm the next step.

No measurements yet? Send your vehicle details and ask us to source a steel reference rotor.