The 3 Most Common Causes of a Stuck Brake Caliper
Stuck brake calipers aren’t that common, but when they do occur, there are only a few things that can cause it. The 3 most common are:
1) Brake Caliper Pistons and Brake Hoses
The most common cause of stuck brake calipers is the caliper pistons and brake hoses. The pistons have rubber sleeves that lubricate and protect them. But when this rubber breaks, dirt and rust can build up inside the caliper, reducing the piston’s ability to slide. The rubber linings on brake caliper pistons are often torn by careless mechanics when installing new brake pads, but they can also wear out over time.
As for brake hoses, they wear out over time. If the hoses crack or break, brake fluid will flow onto the pistons, slowing your vehicle down. In the worst case scenario, the fluid can’t flow back into the master cylinder, causing the caliper to stick.
2) Brake Caliper Guides
Another common culprit is the brake caliper guides. Each brake caliper has grooves that the brake pads slide into when you press the brake pedal. When you take your foot off the brake pedal, the brake pads slide out of the grooves.
However, if dirt or corrosion builds up in the grooves or on the brake pads, the pads can get stuck in the grooves. This prevents the brake pads from sliding out of the grooves when you take your foot off the brake pedal, and keeps the calipers from getting sticky when you apply the brakes.
3) Caliper Bolts
Another possible cause of frozen brake calipers are the brake caliper screws. These bolts are made to slide, so if they dry out too much, they can easily become sticky if not lubricated regularly.
The bolts have a protective layer of rubber to keep the lubricant inside the bolt, but this rubber can easily crack and leak lubricant. This often happens by mistake when mechanics install new brake pads on a vehicle.
When the bolts dry out, rust and dirt can build up, causing further damage to the sliding mechanism.
Case Study: All Brake Calipers Completely Stuck
If you have an issue with your brakes completely stuck and your car not moving at all, you can read my personal experience below. Maybe you have the same problem as me.
I myself ran into an issue where the brake pads were gripping the rotor disc so tightly that the car would not move. So I started narrowing down the problem step by step. Here is the diagnostic process I went through to finally find the cause:
- Check brake calipers and pistons –> OK
- Check brake hoses and lines → OK
- Check brake fluid –> OK
- Check brake line connections → OK
- Check master brake cylinder –> OK
- Drain brake fluid → OK
Result = problem still exists
And finally I removed the brake booster and measured the length of the pushrod. I found that because the push rods were longer than the standard length, the rods were constantly pushing the master cylinder and applying brake fluid pressure to the brake caliper pistons on the brake rotors.
