BRAKE PAD AUTOPSY: What Does Noise Look Like?

I recently bought an Olloclip for my iphone. It has a great marco lens for zooming in on small details. It gave me a chance to look at some brake pads I recently took off a truck. It is amazing how bad some brake pads can look up close and how a cheap pad can fail prematurely and cause noise.

This is a sign the friction material is separating from the backing plate.

This is a sign the friction material is separating from the backing plate.

What is this? A crop circle? No, it is  fracturing of friction material around a molding hole in the backing plate. This can happen on some pads for two reasons. First, different rates of thermal expansion over many heat cycles can cause the material to crack. Second, the backing plate might be too thin or poorly engineered and flexes too much and causing the friction material to crack.

 

 

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This what happens when the puck of friction material falls out.

Over time, a puck of friction material can even come loose. Not only can this hurt braking performance, it can cause noise and even more friction material to come off the face of the pad.

The holes in the backing plate are for integral molding where the friction material flow through the holes to bond the friction material to the backing plate. This method replaced rivits for some applications.

The friction material is lifting from the backing plate

The friction material is lifting from the backing plate

Keeping friction material attached to a backing plate is a tricky piece of engineering. The friction material has to endure mechanical forces and an environment that is highly corrosive. If the bonds between the friction material are weak, water, road salt and de-icing brines can work their way between the components. This can cause the friction material to separate from the backing plate. This hurts braking performance and causes noise.

Most cheap brake pads cut corners when it comes to the backing plates. It maybe a thinner gauge steel or misplaced holes that allow the pad to flex and fracture the friction material. It might also be the anti-corrosion paints or coatings needed to protect the against rust getting between the friction material and plate. Hey, you get what you pay for.
There are some premium backing plates on the market that come with premium pads.  NUCAP’s NRS puts hundreds of small hooks on the plate that grab the friction material. This gets rid of the holes and the problems seen above. According to NUCAP, the hooks increase the shear strength and can prevent edge lift of the friction material. Not only can it increase overall safety, but it can decrease incidents of unwanted noise.

NUCAP NRS

NUCAP NRS

Since the hooks replace adhesives, the plate can be plated with anti-corrosion surface that can out last paints or coatings. NRS-applied pads allow friction manufacturers to engineer friction products that demonstrate an extended duty cycle by retaining overall plate/pad integrity to the absolute end of friction wear.