Brake jobs are generally one of the easier DIY chores. That’s not to say things can’t go wrong. I’ve been a mechanic for over twenty years. I know even the simplest jobs can turn to crap. But don’t panic. Together, we’ll get this figured out very shortly.
New brakes commonly smoke because the brake pads bind. The 4 most common reasons new brakes bind and smoke on one side include:
- Excessive brake pad backing plate paint
- Brake pad carrier corrosion buildup
- Binding floating caliper pins
- Partially seized caliper piston
In this post, you’ll learn all the common reasons new brakes smoke. You’ll learn how to figure out why you are smoking and what you can do to fix it.
Why The Brake Smoke?
Smoke from the brakes is, as you know, caused by the brake pad sticking to the rotor. The constant friction causes heat which, if ignored, will damage both the pad and rotor.
Brake smoke is a common problem and is easy to diagnose. We can quickly rule out a brake system-wide issue as the smoke only comes from one side of the vehicle.
When brakes are applied, the caliper piston pushes the pad against the rotor, slowing and stopping the vehicle. When the brake pedal is released, the piston retracts, which allows the pads to move away from the rotor. When brakes are smoking, it simply means the pads aren’t moving away from the rotor.
There are several possible reasons the pads are not moving away from the rotor. Here’s a list of the usual causes, together with how to diagnose them and fix them.
1 Excessive Brake Pad Backing Plate Paint
Brake pads aren’t generally an expensive item unless, of course, your pads are competition-style pads. The point is, the quality of pads varies a lot. Even the main dealer, Original Equipment Manufacturer (OEM) pads, can suffer from poor fitting.
I worked for a large Chevrolet dealership, and even though we used OEM parts (ACDelco pads), they didn’t fit correctly. The pads were good quality but the metal backing plate never quite fit right. All the mechanics were aware of the problem, and given the nature of mechanics, we just worked around the problem.
And the problem was simply too much paint on the pad’s metal backing plate. In the manufacturing process, the black paint used to protect the pad’s metal backing plate from corrosion would pool where the pads sit in the brake carrier.
The result was a super tight-fitting brake pad that would sometimes bind.
How to diagnose excessive brake pad paint: Allow the brakes to cool down before removing the affected wheel and brake caliper. Use a bungee cord or wire to suspend the caliper.
Using a flat screwdriver, attempt to move the pads in the carrier. The pads should be snug but not tight. Tight pads will press against the rotor as the brakes are applied but not move away from the rotor after brake release.
With pads removed, check the arms of the pads for pooling paint coating, where they meet with the carrier rail.
How to fix excessive brake pad paint: The solution is simple, as I’m sure you’ve no doubt guessed already, remove the paint, right? Using a flat file, remove some material from the pad arms contact patch.
File sparingly and make several test fits. Removing too much material will cause the pads to fit loosely in the carrier and cause an annoying click sound when applying the brakes.
On the final fit, add some pad lube to the contact patch and the rails of the carrier. This helps the pads move like butter. You’ll find the lube I use on the Brake repair tools page and if you need brake system parts, check out the Amazon link below.Amazon Brake System Parts
2 Brake Pad Carrier Corrosion
Corrosion on a car’s underpinnings is unavoidable. Metal components like brake carriers aren’t painted, add brake dust, and road salts, and you get perfect conditions for corrosion buildup.
The brake carriers hold the brake pads in place on a rail. The caliper fits over the pads and is bolted to the carrier. It is mission critical that the pads slide cleanly across the rails of the carrier. Corrosion on the carrier rails is a really common reason for brake pad binding.
How to diagnose carrier corrosion: Allow the brakes to cool down before removing the affected wheel and brake caliper. Use a bungee cord or wire to suspend the caliper. Using a flat screwdriver, attempt to move the pads in the carrier. The pads should be snug but not tight.
With the pads removed, check the rail on the carrier for corrosion. The rail should look smooth. Corrosion buildup will cause the rail surface to appear uneven with deep depressions.
How to fix carrier corrosion: You’ve guessed this solution too, I’ll bet. Clean the rail using a wire brush and rough grit sandpaper. If needed, use a file to make a flat-level surface. Avoid using a power grinder as this could remove too much material and cause the pads to fit loosely in the carrier.
Test fit the pads as you go. They should fit snug but not tight. As a rough guide, you shouldn’t need a screwdriver to remove them.
On the final fitting, apply some brake lube to the rails and the pad arms contact patch. You’ll find the brake lube I use on the Brake repair tools page.
3 Binding Floating Caliper Pins
Calipers come in two flavors, fixed and floating. Fixed is reserved for high-performance vehicles and commercial trucks. Fixed calipers are, well…fixed, meaning they don’t move, so if you have fixed calipers, this doesn’t apply to you.
In the beginning, all calipers were fixed. The floating caliper was developed as a cheaper option and is by far the most common type of brake caliper. Your vehicle will most likely have floating calipers fitted.
Floating calipers get their name as they float across the rotor as the brakes are applied. Floating simply means the caliper slides across the rotor ever so slightly before the pads make contact with the rotor.
The floating caliper was cheaper to make, and that’s why it’s so common. The sliding action allows for only a single piston instead of the minimum of two on a fixed caliper. The floating caliper employs two pins that are attached to the brake carrier to allow it to slide across the rotor.
The floating caliper is a great system; however, it suffers from a common problem. Torn protective rubber pin boots allow moisture and grit to enter the bore, which develops into corrosion, causing the pins to bind or seize.
How to diagnose binding caliper pins: Allow the brakes to cool down before removing the affected wheel. Using a screwdriver, pry the caliper forward. This pushes the piston into the caliper and allows us to test the slide pins.
With the piston retracted by a half-inch, using just your hand to grip the caliper, slide it from side to side. It should be easy to slide the caliper by a half-inch. If the caliper won’t move, or it’s difficult to move, you’ve found your problem – the caliper pins are binding.
How to fix binding caliper pins: Go ahead and remove the caliper; use a bungee cord or wire to suspend the caliper from the suspension spring. Remove the pins from the carrier. They may need some encouragement. It’s not uncommon for some pins to seize solid inside the carrier, and the only fix is to replace the carrier.
Most pins, however, can be removed and cleaned with a wire brush and coarse sandpaper. Use silicone grease on the pins and replace the rubber dust boots if damaged. Silicone grease is preferred as petroleum grease will damage the rubber dust boots.
4 Partially Seized Caliper Piston
A seized caliper is all too common. The piston inside the caliper develops corrosion and eventually binds the piston inside the caliper. Applying the brakes allows the piston to move outward, but the corrosion prevents the piston from moving back in when the brakes are released, effectively sticking the brake on.
How to diagnose seized caliper piston: Allow the brakes to cool down before removing the affected wheel.
Using a screwdriver, pry the caliper forward. If the caliper won’t move, it is very likely the caliper piston is seized, also known as frozen.
There is another possibility for the lack of movement in the caliper piston. However, it is less likely – a collapsed brake. A flexi hose will allow fluid travel to the caliper but not return, effectively sticking the brake on.
Diagnosing the caliper and Flexi hose will require opening the caliper bleeder. Whenever a bleeder is opened, it introduces air to the system, which needs to be purged.
You can bleed brakes solo, but you’ll need brake bleeding tools which you can check out on the brake tools page. It is also possible to bleed brakes without special tools, but you’ll need a helper.
If you need help with brake bleeding, check out this post, it covers a simple two-man brake bleeding procedure.
Go ahead and open the caliper bleeder while prying the caliper forward. Two possible outcomes are possible:
1 – No fluid shoots from the bleeder. The caliper piston is indeed seized.
2 – Fluid does shoot from the bleeder while prying the caliper forward. Caliper is good. The fault lies with the Flexi hose.
How to fix seized caliper piston: The only repair here is to replace the caliper, and it’s best to replace both calipers on the same axle, i.e., both fronts or rear. The brake system will need bleeding.
Calipers usually fail because of contaminated brake fluid. Brake fluid attracts moisture, and that causes corrosion in brake lines and caliper pistons. Fluid should be changed every three years.
When changing out the calipers, flush the brake fluid too.
How to fix a brake Flexi hose: The only repair here is to replace the Flexi hose, and it’s best to replace all four Flexi hoses. The hydraulic fluid system will need bleeding, so best to flush the system too.
Brakes are serious business; if you aren’t confident they are right, go to your local mechanic and have them checked. Alternatively, check out the JustAnswer link below, where you can talk to a mechanic directly right now.
Check out all my favorite tools on recommended tools page.
You may find the brake resources page useful, it’s a fluff-free guide to DIY brake repairs.
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John Cunningham is an Automotive Technician and writer on Rustyautos.com. He’s been a mechanic for over twenty-five years and has worked for GM, Volvo, Volkswagen, Land Rover, and Jaguar dealerships.
John uses his know-how and experience to write fluff-free articles that help fellow gearheads with all aspects of vehicle ownership, including maintenance, repair, and troubleshooting.