What Would Cause a Back Tire To Lock Up? (Explained!)

Tire lock-up can be very dangerous and happens more often than we like. Many drivers are driving on the highway and suddenly their back tire locks up. Getting to safety with a locked-up back tire can be quite challenging. But, what would cause a back tire to lock up? Is there any way to prevent this?

In this article, I am going to talk about what would cause a back tire to lock up, how to fix it, and how much it will cost you.

Key Takeaway

  • A seized piston on a brake caliper is the most common reason why tires lock up.

How Do You Fix a Seized Rear Wheel?

  • Park the vehicle on the leveled ground and engage the parking brake.
  • Losen the cap on the brake master cylinder to allow air.
  • Jack the vehicle and place it on a jack stand.
  • Remove the wheel.
  • Remove the top and bottom slider pins on the caliper.
  • Visually inspect the braking assembly and try to move parts with your hands.
  • Clean the brake parts with brake cleaner.
  • Reinstall the wheel.
  • Take the vehicle for a test drive.

What Would Cause a Back Tire To Lock Up?

What Would Cause a Back Tire To Lock Up

The most common reasons that would cause a back tire to lock up are sized pistons on the brake calipers that won’t retract and release the brake pads or the flex hose that acts as a link between the rigid brake line and the brake caliper is damaged on the inside and allows brake fluid to go into the brake caliper but not out of the brake caliper in order to release the pistons.

The brake caliper assembly uses the hydraulic force from the brake pedal to squeeze the brake pads to the rotor surfaces, thus creating friction and decelerating the wheel. The caliper assembly consists of the caliper bracket, slider pins, dust boots, inner brake pad, outer brake pad, caliper frame, and a piston inside the caliper frame.

When you press the brake pedal, the caliper will receive a high-pressure hydraulic fluid from the brake master cylinder. This fluid will then push the piston which makes the inner brake pad squeeze against the disc rotor surface from one side and the outer brake pad from the other side. When you release the brake pedal, the fluid then travels back from the flex hose and into the brake master cylinder.

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When pistons on the brake calipers seize, they are actually applying constant braking on that particular wheel and will cause it to lock up. This can happen on a front or a back wheel. It will appear as if you are constantly pressing the brake pedal, but only one tire will lock up.

If the flex hose that supplies the brakes with pressurized fluid gets damaged, the fluid will only travel to the brake caliper where it will apply pressure, but when you release the brake pedal, the fluid will stay there and apply constant pressure and cause the back tire to lock up.

What Does It Mean When Your Tire Doesn’t Move?

What Would Cause a Back Tire To Lock Up (Explained!)

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If your tire doesn’t move at all or has difficulty moving due to a faulty braking assembly, you will be able to feel a burnt smell when driving your vehicle from the brakes being constatly applied.

The pistons in the brake caliper can get seized up in the bores and it won’t allow that piston to go back, so it’s holding constant pressure on the brake pads and your tire won’t move.

Also, the brake lines that distribute the fluid from the brake master cylinder into the calipers can be damaged and only supply highly pressurized fluid to the brakes, but not from the brakes. This means that the fluid will apply pressure to the brakes and activate them, but won’t retract the fluid once you release the braking pedal. This also results in constant pressure on one or more wheels and the tire or tires won’t move.

The slide pins for the caliper can also be the cause of your tire not moving. They have a job to slide the caliper towards the brake pads when you press the brake pedal. However, if they get seized up in a fully activated position, that particular wheel will be locked up and won’t move. If this is the cause, you will notice that the brake pads are not worn out evenly. The reason behind this is that there are two sliding pins on the brake calipers, and only one of them can seize up.

How Do You Fix a Seized Rear Wheel?

Driving with a seized rear wheel is merely impossible and has to be dealt with immediately. However, many of us don’t know what to do once we encounter this issue. That is why I am going to show you how to fix a seized rear wheel without any special mechanic skills.

1. Required tools for the job

  • Jack
  • Jack stands
  • Wrench
  • Brake cleaner

2. Park the vehicle on a leveled ground

Since we will be removing the seized rear wheel in order to fix the issue, we will need to jack up the vehicle. It is very important that your vehicle is parked on level ground and is in gear. You don’t want to apply the hand brake because it will create pressure on the brakes. You won’t be able to release the rear caliper from the disc at the back. Just block the vehicle from moving by placing stones behind the tires. Make sure that the vehicle is actually parked on a hard surface and not on a dirt road because the jack will sink into the ground.

3. Loosen the cap on the brake master cylinder

What Would Cause a Back Tire To Lock Up

Before we proceed with dealing with the seized rear wheel, we need to loosen the cap on the brake master cylinder. The reason why I like doing so is that loosening the cap, it just breaks the air seal so when you are squeezing the caliper on the rear of the car, it lets the brake fluid travel in the master cylinder reservoir without any pressure stopping it from traveling up the system. Just make sure to remember to tighten the cap once you are done with this task.

The brake master cylinder is located under the hood and on top of the braking system. It has a plastic cap on top of it that is labeled with Braking Fluid or some other wording related to that.

4. Jack the vehicle and place it on a jack stand

To find the jacking points on your vehicle, you will need to check the owner’s manual. Usually, there is a jacking point right next to each wheel. Once you have located the jacking point next to the seized wheel, jack it up and place it on jack stands for safety.

5. Remove the tire

Once the vehicle has been secured on a jack stand, grab a wrench and remove the tire. The most common thread sizes are 10mm, 12mm, 14mm, 7/16″, 1/2″, 9/16″, 5/8″. Once you’ve done that, place the wheel somewhere out of the working zone.

6. Remove top and bottom slider pins

What Would Cause a Back Tire To Lock Up

The caliper is secured in place by two slider pins that have 4-3/8” bolts. One is on top of the caliper and another is on the bottom. So, grab the corresponding wrench and remove both bolts. At this point, the caliper will come out completely.

7. Visually inspect the braking assembly and try to move parts with your hands

So, basically, right now you are looking at the braking assembly on the rear wheel. Inspect the brake pads and just see how hard it will be to actually remove them. If they seem rusty, or stuck, take them out for cleaning. Next, move the sliding pins. They should be able to move quite freely. If they are not, just pull them out and prepare them for cleaning.

8. Clean the brake parts with brake cleaner

What Would Cause a Back Tire To Lock Up

Start by cleaning the brake pads and the shims that the brake pads sit on. Make sure to remove any grease or rust. Then, move on to cleaning the slider pins. But also make sure to clean the housing where the slider pins sit in. The piston inside the caliper will also require cleaning. Overall, just completely spray the whole braking assembly with the brake cleaner and let the components dry before reinstalling them.

9. Reinstall the brake parts

Once all of the brake parts have been cleaner, it is time to reinstall them. Insert the brake pads on the shims, and insert the slider pins back in. Reinstall the two bolts that hold the caliper in place. Reinstall the tire and tighten the bolts. Also, make sure to tighten the cap on the master brake cylinder.

10. Take your vehicle on a test drive

This is very important. When working on your brakes, there could be a possibility that you have somehow installed some part of the braking assembly incorrectly. What I always do when I first take the vehicle on a test drive after fixing the brakes is apply the brakes before moving. So, put your vehicle in neutral and apply the brakes, to see if they work. If the brakes are working then take the car out and see if the rear tire is spinning correctly.

How Much Does It Cost To Fix Locked Brakes?

The cost of fixing locked brakes depends on which part of the braking assembly has failed. Replacing a single caliper can cost up to $110. The rubber bushings on the sliding pins cost around $10 per wheel whereas the actual sliding pins can cost up to $12 per wheel. Most brake pads cost around $30, but you can get high-quality ones for $60.

Getting your locked brakes fixed at the mechanic usually costs around $60, but it will cost you none if you do it yourself.

Igor Iwanowski

I am a certified Automotive Service Excellence (ASE) mechanic since 2018. I specialize in Brake systems, dashboard warning lights, EGRs, general engine problems, EVAP and Emissions issues.

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