Why Does My Vehicle Pull to One Side When Braking?
When your vehicle pulls to one side when braking, most likely the fault lies in the brake system. There are several brake system problems that can cause this:
- A leaking wheel cylinder
- A brake pad or shoe that is contaminated with grease or fluid
- A frozen caliper or wheel cylinder piston
- A bad automatic adjuster on your rear drum brake or parking brake
- A restricted brake hose or line
- A brake component in need of attention
Sometimes, though, the fault is not with the braking system at all: pulling while braking can also be caused by a faulty tire, or loose or worn suspension components.
Whatever the source, driving with a pulling brake condition is dangerous. This guide can help you locate the source of the problem through a series of quick inspections and diagnostics you can apply at home to common brake system issues.
Start by asking yourself this question: Is the problem with the front or rear wheels?
Usually, when the problem comes from one of the front brake assemblies, you'll feel a strong pull on the steering wheel when applying the brakes. But when the problem comes from one of the rear brake assemblies, you may not notice a pull unless you brake hard. Braking hard will cause one of the tires to skid and squeal because it'll lock up. Sometimes when a rear brake assembly is bad you may not notice a pull at all, but find out about the problem when you notice uneven wear on the tires.
This preliminary diagnostic can help you locate the source of the problem faster. Once you know which side is causing you trouble, it's a good idea to take a look at the opposite assembly as well to get a general idea of the condition of your brakes.
Whatever the source, driving with a pulling brake condition is dangerous.
Common Causes of Pulling Brakes
In the sections below, I discuss how you can detect these possible problems and how to deal with them.
- Contaminated brake lining
- Uneven brake wear
- Brake fluid leak
- Frozen piston in a caliper or wheel cylinder
- Rear brake adjuster
- Faulty tires
Contaminated Brake Lining
Brake pads or brake shoe linings contaminated with fluid or grease will prevent the brake assembly from working properly on that side of the system.
- Check the suspected front or rear brake assemblies by lifting and safely supporting the vehicle on jack stands.
- Remove the wheel-tire assembly.
- Check the brake pad and rotor (front brakes), or shoes and drum surface (rear brakes), for a coating of grease or oil or some other foreign matter.
- You may need to find the source of the leak or contamination.
- Make the repairs and replace the pads or shoes as necessary.
Uneven Brake Wear
Brake pads and rotors should wear gradually and at the same rate on each side, just as brake shoes and drums should brake gradually and at the same rate.
But brake system problems may cause the brake assembly on one wheel to suffer excessive wear compared to the assembly on the opposite wheel, causing a pulling brake condition.
Inspect both front or rear wheel assemblies for uneven wear. Excessive wear of a brake pad or rotor on one side may be a sign of brake system problems that you need to further investigate.
Check the operation of the brakes to find and correct the problem.
If you are dealing with uneven wear of brake pads, shoes, rotors or drums, check for:
- a stuck caliper piston
- a frozen wheel cylinder piston
- loose or stuck mounting hardware
- a loose or stuck operating mechanism
- proper caliper slide and pin lubrication
Consult your vehicle repair manual. If you don't have the manual yet, you can buy an inexpensive, aftermarket copy at Amazon. come with step-by-step procedures to troubleshoot most systems and components in your vehicle, along with instructions to replace faulty parts as necessary. Haynes manuals
Brake Fluid Leak
A leaking caliper piston or wheel cylinder will prevent that brake assembly from working properly and cause a pulling brake condition.
Checking a Brake Caliper
Check the front wheel assemblies by lifting the tires off the ground and safely securing the car on jack stands. A leaking caliper piston most likely needs a new seal, but you need to check the piston and cylinder themselves for damage too.
Usually, corrosion is behind this type of leak. If you haven't replaced the brake fluid in more than two years, moisture is likely attacking the sealing surfaces inside the caliper.
It's possible to rebuild a caliper assembly if the cylinder is not too worn or damaged, but usually it's better just to replace the caliper with a new unit. If you want to rebuild the caliper, follow the procedure described in your vehicle repair manual. You'll need to hone the cylinder and replace the seal and dust boot.
Checking a Rear Wheel Cylinder
Checking a rear wheel cylinder is similar to checking a caliper piston for leaks:
- After removing the wheel-tire assembly and drum, check around the cylinder boot for a dump area. You may need to pull back the boot to check for leaks.
- If necessary, replace or rebuild the wheel cylinder.
- If you decide to rebuild the cylinder:
- Make sure the cylinder, the pistons, and the compression spring and expanders are in good condition.
- Hone the cylinder and replace the rubber cups and boots.
- Follow the instructions in your vehicle repair manual.
- Replace the brake fluid in the system as well.
Frozen Piston in a Caliper or Wheel Cylinder
To check for a possible frozen caliper:
- Lift the front or rear of the vehicle so that both tires are off the ground, depending on the brake assembly you want to check.
- Safely support the vehicle on jack stands.
- Ask an assistant to apply the brakes and keep the brake pedal depressed.
- Try spinning each wheel by hand.
- If you CAN turn one of the wheels, that brake assembly isn't working properly.
- Repeat the test but this time without applying the brakes. Both tires should spin freely. If one of the tires drags, there's a problem.
If you found a problem in the previous test, you may be dealing with a frozen caliper or wheel cylinder, or a restricted brake hose or line that is preventing brake fluid to reach the piston. The inner liner in a brake hose can deteriorate, weaken and collapse, restricting the free movement of the brake fluid and operation of the caliper or wheel cylinder piston. However, you won't be able to tell whether a brake hose has internal damage just by looking at it.
Before testing a brake hose, make sure that the piston in the caliper or wheel cylinder is not stuck due to an internal problem (damaged cylinder, piston or seal), and check for problems with the mounting or operating hardware, or, in some models, a caliper that is not sliding freely on the rail.
Testing a brake hose:
- Lift the front or rear of the vehicle and safely support it on jack stands, depending on the brake assembly you need to check.
- Working on the faulty brake assembly, momentarily loosen the brake hose at the master cylinder end, and try spinning the tire by hand again.
- If the tire spins now (or the caliper or wheel cylinder seems to unfreeze, depending on the particular problem), most likely the problem lies with a component located between the master cylinder and the brake hose (perhaps a bad ABS system component) or a restricted brake line.
- Tighten the brake hose.
- If the tire still doesn't spin freely, repeat the test. This time, loosen the bleeder screw at the caliper or wheel cylinder.
- If the wheel spins freely (or the caliper or wheel cylinder seems to unfreeze), probably the issue lies with the brake hose.
Watch the next video so that you know how a faulty brake hose can make a caliper piston stick and create a pulling brake condition.
Rear Brake Adjuster
A rear wheel brake assembly can also fail when the brake adjuster freezes or fails. The brake shoe adjusters should maintain the correct distance between the brake shoe lining and the drum as the lining wears. Most vehicles use a star wheel (screw) type mechanism for the adjuster, while some modern vehicles may use a latch adjuster type mechanism.
- Lift and safely secure the vehicle on a jack stand.
- Remove the wheel and drum.
- Check for adjuster free movement.
- Consult the repair manual for your particular vehicle model to repair or replace the adjuster, if necessary.
If you haven't found the source for the pulling while braking, a quick inspection of the tires can save you time, and possibly money.
Problems may arise with the plies or belts that compose the internal body of the tire. Although it's hard to know if a tire has internal problems just by making a visual inspection, you can swap a front and a rear tire and see if the pulling brake problem goes away. If it does, most likely the problem is with the tire itself.
After Ruling Out Brake And Tire Problems, Check the Suspension
With the guide above, you can check the most common problems that lead to a pulling brake condition before you decide to send your car to the shop. However, if going through the list of common sources doesn't render a good diagnostic, check for loose or worn suspension parts that may be causing the problem, like damaged bushings, or loose or worn hardware on a lower control arm, tie rod, ball joint, strut rod or torsion bar, depending on the particular model. Consult your vehicle repair manual to check these components.
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© 2018 Dan Ferrell