Car Shakes When Braking

Car Shakes When Braking

Introduction

Nothing can be more alarming than feeling your vehicle shake or vibrate when applying the brakes. This unsettling sensation immediately raises concern about the safety of you and your passengers. While shakes and vibrations can stem from minor issues like brake dust buildup,

they can also indicate serious problems with rotors, calipers, wheel bearings and other critical brake components. Diagnosing and resolving the root cause promptly is crucial. This article explores the common reasons a car shakes when braking along with troubleshooting tips to determine the exact problem.

Causes of Shaking When Braking

There are several potential causes that can produce shaking, vibration or steering wheel wobbles when braking. Here are the most common culprits:

Warped Rotors: Over time, heat stress and wear cause rotors to become warped or distorted. This creates vibrations when braking due to uneven contact with brake pads. Warped rotors must be resurfaced or replaced.

Worn Brake Pads: Excessively worn pads lose braking power and contact area, leading to vibrations under braking. Replacement is required to restore proper friction.

  • Brake Dust Buildup: A sticky layer of brake dust on rotors can cause uneven braking and wheel shudders when applied. Cleaning removes the deposits.
  • Caliper Issues: Malfunctioning calipers like a stuck piston or loose mount will create an imbalance in braking forces, resulting in shakes and wobbles.
  • Wheel Bearing Defects: Damaged or worn wheel bearings don’t allow the wheel to spin smoothly. This translates to vibrations when braking at high speeds.
  • Loose/Damaged Components: Various loose suspension, steering, or brake components like ball joints, sway bar links or brake hardware will exhibit shaking symptoms under braking forces.
  • Tire Defects: Separation, excessive wear, or balance issues with tires can induce vibrations when braking. Rotating or replacing tires typically solves this.

Misalignment: Improper wheel alignment angles will lead to uneven tire wear and balance problems that create shakes when braking. An alignment corrects this issue.

Causes Of Shaking When Braking
Causes of Shaking When Braking

Troubleshooting Brake Shakes

Inspect pads and rotors: Check for extreme wear or uneven surfaces on pads and rotors. This is the most common source of brake shakes. Replace components as needed.

Test at various speeds: Vibrations that only occur at certain speeds help indicate the failing component. Wheel bearings typically cause shakes only at highway speeds for example.

  1. Check for binding: Stuck or seized caliper pistons prevent smooth braking and create vibrations. Lubricate caliper slides if binding is found.
  2. Listen when braking: Unusual noises when braking may assist diagnosis. Grinding suggests worn pads. Squeaks indicate brake dust buildup. Knocking can mean a loose component.
  3. Test brake bias: Have an assistant press brakes while you remain in the car. Uneven grabbing and release indicates a caliper or proportional valve issue.
  4. Check tire condition: Inspect for abnormal or uneven tire wear. Balance or rotate tires if they are determined to be the source of vibrations.
  5. Road test before and after repairs: Verify shakes are resolved after each component is addressed, narrowing down the faulty part.
  6. Inspect suspension: Worn ball joints, bushings, and bearings will exhibit shakes under hard braking. These require replacement.
Troubleshooting Brake Shakes
Troubleshooting Brake Shakes

Resolving Common Causes of Brake Shakes

Here are tips on addressing some frequent causes of brake vibrations:

Warped Rotors – Rotors should be measured with a dial indicator for distortion. Thickness should also be checked. Resurfacing can remove minor warpage if rotor is still within specs. Replacement is required for excessive run-out or undersized rotors.

Worn Pads – A brake pad with less than 3mm of friction material requires replacement. Always replace pads in complete axle sets. Lubricate contact points during replacement. Break-in pads properly with a series of gentle stops.

Brake Dust – Use a wire brush attachment on a power drill to scrub away caked on brake dust on rotors, pads, and calipers. Avoid breathing dust particles. Finish by rinsing components with water.

Caliper Issues – Sticking calipers must be rebuilt or replaced. Verify caliper mount and slides are secure. Lubricate pins and fastener threads during replacement to prevent binding.

Wheel Bearings – Any play, roughness or wobble when spinning the wheels indicates worn bearings. Complete hub assemblies typically must be replaced. Proper torque on the axle nut is critical.

Loose Components – Methodically check and secure all suspension, steering linkage, and brake hardware. Replace any severely worn or damaged parts. Use thread locker on critical fasteners.

Resolving Common Causes Of Brake Shakes
Resolving Common Causes of Brake Shakes

Prevention and Maintenance

Practicing proactive brake maintenance helps avoid shakes and extends system life:

  • Regularly check pad thickness and change before they are fully worn.
  • Inspect rotor condition every pad change and resurface or replace as needed.
  • Lubricate caliper slides and pins with each pad swap using silicone paste.
  • Have wheel bearings inspected annually for any play or signs of wear.
  • Evaluate vibration causes anytime pedal pulsations are felt while braking.
  • Address any steering, suspension, or wheel balance issues right away that could transfer shakes to braking.
  • Flush old brake fluid and refill with fresh DOT4 fluid every 2-3 years to avoid moisture buildup.

signs of worn wheel bearings in a nutshell:

  • Grinding, rumbling noises from the wheel
  • Wheel wobble when braking
  • Vibrations in steering wheel at high speeds
  • Uneven tire wear
  • Loose feeling in steering wheel
  • Bearing seal leaks
  • Clicking, roughness when turning wheel
  • Car pulls to one side when accelerating

Any of these symptoms means the wheel bearings need to be replaced. Making repairs promptly avoids further damage and unsafe conditions.

tips for cleaning brake dust off rotors:

  • Use brake parts cleaner spray as a degreaser first
  • Scrub with a wire brush drill attachment
  • Wipe clean with a lint-free rag
  • Sand lightly with 200 grit sandpaper if needed
  • Rinse thoroughly with water after cleaning
  • Allow rotors to completely air dry
  • Wear gloves and eye protection when cleaning

Taking the time to fully clean brake rotors removes contaminants and ensures smooth, even braking surface contact.

  • CRC Brakleen
  • 3M 08984 Brake Parts Cleaner
  • Permatex Brake Cleaner
  • WD-40 Specialist Brake Cleaner
  • Berryman Chem-Dip
  • Carquest Premium Brake Parts Cleaner

Look for products designed specifically for brake components that will quickly break down contaminants without damaging rotors. Use gloves and proper ventilation.

FAQs

Q: Is it safe to drive with brake shudders and vibrations?

A: No, any shaking or vibration when braking should be addressed immediately as it indicates problems with braking components. Driving could worsen damage.

Q: What is the easiest first step to diagnose brake shakes?

A: Visually inspect the brake rotors and pads for signs of warping, uneven wear, or contamination as these are most common causes.

Q: Can worn out shock absorbers cause vibrations when braking?

A: Yes, bad shocks can sometimes transmit vibrations to the brakes. Worn wheel bearings and ball joints can also contribute to brake pedal shakes.

Q: How do I know if rotor warpage is beyond resurfacing limits?

A: Use a dial indicator to measure lateral runout. More than 0.003 inches of runout on a rotor surface often exceeds resurfacing specs.

Q: Will anti-lock brakes still function properly if pads are worn out?

A: No, worn brake pads will deactivate the ABS system. Pad replacement is required to restore proper anti-lock functioning.

Q: Can unbalanced wheels cause my car to shake when braking?

A: Yes, unbalanced wheels, bent rims, and certain tire defects like separated belts can all contribute to brake vibrations.

Conclusion

Noticing your vehicle shaking, wobbling or vibrating when braking should be addressed immediately to determine the cause and prevent accelerated wear of components. Warped rotors are the most prevalent problem, but worn pads, contaminated brakes, bad calipers,

defective wheel bearings or balance issues can also produce symptoms. Methodically testing and inspecting each system while referencing the troubleshooting tips in this article will help you get to the root of the problem. Performing regular brake maintenance and responding promptly to any vibrations will result in smooth, safe braking.

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