Brake Pad Info
The biggest complaint Aston owners have about their brakes is brake dust. The runner up complaint is noise - one is brake squeal, the other is a 'chirping' sound. Both are from the brakes, and both are caused by the same thing, but they are in fact different.
The dust and squeal are both caused by the OEM Pagid 4-2-2 brake pads. Some people call them "Brembo pads" because the rest of the brakes are from that company, but they’re actually made by Pagid. The pads are fantastic at what they're designed to do: they stop the car. They're also very well balanced and smooth at all speeds - not grabby like some high performance brake pads can be.
Patting Aston Martin on the back for making a car that can stop may seem like a simple enough thing, but it isn't.
Aston Martins go really fast. An early V8 Vantage can go nearly 180 mph and a few Aston models can eclipse the 200 mark. To make the cars safe enough to sell to the public at large, the brakes have to be able to stop the car from those really high speeds. That means the brakes are big and aggressive and, unfortunately, that comes with some downsides.
All brake pads will create brake dust. Brakes work by clamping pads onto a rotor, creating friction and slowing down the car. That friction creates dust and no pad will be exempt from that, but the amount of dust (and even the color of it) can vary wildly. In general, the more aggressive the pad is, the more dust it will create. The OEM pads create a lot of dust.
There are two primary causes of brake squeal; one is preventable, the other is due to pad design.
The preventable cause is preventing the metal-on-metal contact between the brake pad backing plate and the brake caliper pistons. After a bunch of people complained about brake squeal from the early V8 Vantage and DB9, Aston Martin started using shims to act as a buffer between the pads and pistons. It can help, but it isn't ideal. The best thing to do that I've come across is to use a high-quality anti-squeal paste (or grease, the terms are often interchangable).
When you change out your brake pads, make sure you clean all of the components and apply anti-squeal to everything during reassembly. DO NOT get anti-squeal on the brake pad friction material or the swept surface of the brake rotors.
The design element that causes brake squeal is that the OEM pads aren't chamfered. Chamfering is creating a beveled corner on the leading and trailing edges of the brake pads. The basic idea is that the chamfering creates a smooth transition for the contact between the brake pads and rotors.
For an easy way to demonstrate this, get a piece of paper and a pencil with a flat-top eraser. Place the eraser on the paper so it's perfectly perpendicular. That is, you want the flat-top eraser to be sitting perfectly flat on the paper. Now drag it to the side. At best, it'll vibrate a bit while dragging. At worst, it'll rip the paper. That vibration is the same thing that happens in your brakes, but happens super quickly so it basically sounds like a continuous squeal. The OEM pads aren't chamfered so they often squeal.
Why aren't the pads chamfered, you ask? Chamfering reduces the surface area of the brake pad friction material, which reduces the ultimate stopping capabilities of the brakes. Remember, the brakes are designed to stop a car going 180 mph, so any reduction in stopping power can have serious consequences.
What Can Be Done?
Although our cars are made to go superfast, most of you don't drive superfast. (Yes, I excluded myself because I do drive superfast. Unless you're my insurance company. Then I don't drive superfast at all. Ever. Also, stop reading my blog.)
Our cars are engineered to perform in ways we rarely-if-ever experience. The perks of performance rarely happen, but the downsides are constant. In this case, it's dealing with a bunch of brake dust and squeal even if the car never hits triple-digit speeds a single time in its life.
Chamfer Your OEM Brake Pads
If you don't want to buy new pads, chamfering your factory pads will help tremendously with brake squeal. It won't do anything for dust, though, as that's determined by the friction material compound.
Use Different Brake Pads
I've talked ad nauseum about brake pad options. Here's a few links:
Let’s Talk About Brakes (blog post)
Braking Mods 2: Pads (mods article)
Porterfield R4 vs R4-S Part 1 (blog post)
Porterfield R4 vs R4-S Part 2 (blog post)
I’ve even made a video about it:
Here’s the thing about brake pads: The factory pads were chosen to match the performance potential of the car. They’re great pads, but have a lot of brake dust and can squeal.
You can get different pads to better suit your needs. With some cars, that means getting more aggressive pads to handle sporty driving. With Astons, it’s getting less aggressive pads to handle daily life. Just don’t out-drive your pads.
A long while back when I first started using and recommending Porterfield R4-S brake pads, people asked if they could be used on the track. I said “no” based on the specs, but people kept asking. So I put them to the test and used them on a track. They did okay for most of the corners, but they failed pretty badly in corners with seriously hard braking. Because of that, I’d never recommend them for track use.
…Unless you have 6-piston front calipers. They make up for the less aggressive compound with a huge increase in surface area.
The pads in the pic above are both Porterfield R4-S front pads. The top pad is for the 6-piston caliper, the bottom pad is for the 4-piston caliper. That’s one serious difference in surface area.
If you hear a 'chirp chirp chirp' sound that seems to come from one of the front wheels... it's probably the handbrakes at the rear wheels.
The factory handbrake pads (which are supplied by Brembo) aren't chamfered, and the pads are constantly skimming the rear rotors. This results in buildup on the leading surface of the handbrake pads. At really low speeds (say, in a parking lot), the straight edge skims across irregularities in the rotor surface which can cause a ‘chirp’ sound. Buildup on the leading edge of the pads can exacerbate the issue.
Fixing the chirp
You can reduce or eliminate the chirping sound by using the handbrake while driving in reverse. This helps clear off the buildup and can get rid of the chirp for a while. It’s also free and only takes a few seconds, so it’s a great thing to do as a quick fix.
To fix the root cause of the problem, you need to chamfer your handbrake pads. You can pull out your factory pads and chamfer them, which will cost nothing but labor. Or you can replace them with handbrake pads that are already chamfered.
I worked with Porterfield to get handbrake pads made in the same R4-S compound that’s so well-loved, and the pads are already chamfered to prevent that obnoxious chirping.