Brake Disc Types

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There are many different types and they all have different properties, find out what to look for when replacing yours.

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Types of Brake Disc

Essentially there are 4 types of brake disc:

Normal
Drilled
Grooved
Dimpled

You also get hybrids of usually 2 of the above, in those cases,
just combine both the pros and cons into one.

Normal Discs

Exactly as you have on your car as standard, flat faced discs. They have more surface area touching the pads when the brakes are applied so initially have better braking power.
The problem with normal discs is that as they heat up you can get a build up of gas between the pad and the disc which causes brake fade and pad glazing. The extra heat can also warp the discs if they are poorly made or have been paired with inappropriate pads.

Drilled Discs

The face of these discs are drilled all the way through mainly to increase surface area so they can rid themselves of heat quicker. The holes also go a little way to stopping the gas build up that causes brake fade. The problem with drilled discs is that the holes can have a tendancy to start cracking and collect dust and debris. This is because discs are cheaply made so the holes are just machined into the face.

The issue with that is the cyclic heat changes they go through. When metal expands and contracts, micro
fractures in the drilled holes start to open up and you start getting visible cracks. That’s obviously not ideal.

This picture is of a motorcycle disc but the idea is similar on the car discs.
Have a look here, here and here for examples.

Grooved Discs

The face of these discs have diagonal lines cut into them, there are two reasons for this.
Firstly they allow the venting of brake pad gasses thus eliminating brake fade.
They also eject brake pad dust to stop glazing of the pad. This keeps the pad face fresh allowing better braking. The problem is that grooved discs have a tendancy to be louder when the brakes are applied due to the scrubbing of the pads.

Discs with grooves should be installed a certain way round. As the disc rotates in its
normal direction, the groove should be spinning outwards. This allows the brake dust
to be ejected away from the hub. Putting them on rotating the wrong way can allow
the brake dust to accumulate in the centre of the hub.

Dimpled

The dimples in a disc clear gas and debris from the pad and to look different..

Combinations And The Unusual

Drilled and Grooved

A very common combination.

Wavy Edged Grooved and Dimpled

The wavy edge is supposed to cause turbulance around the disc to increase cooling.
These are primarily sold by a company called Rotor.

Custom Brake Discs

You can go for run of the mill discs, your standard drilled or grooved (although I don’t recommend drilled discs). You can also get custom discs made up.

These are custom milled on the face side and standard long grooved on the back.
Because of the long groove these discs are quieter than normal grooved discs.

These were custom made an no longer available from the place I bought them.

Should I Just Buy EBC Discs & Pads?

That is up to you but I strongly recommend you don’t. I have tried 4 different combinations on 3 cars
and had 2 cars with warped front discs and 1 car where the pad delaminated from the backing.

The only EBC products I tried that were any good were the Ultimax pads which aren’t “performance” pads.
They are EBC’s standard replacements so you may as well just buy something else.

What Brands Do You Recommend?

Ferodo
Pagid
Brembo
Textar
Mintex

I have personally used all 4 of these brand’s discs and pads and they have been excellent.