Pulsating brakes and steering wheel shake on my 2020 Forester

ClearTheCode admin answer:

Pulsating brakes and a shaking steering wheel during braking are classic symptoms, most commonly pointing to issues with your brake rotors. Here's what's likely happening and what to do:

1. Initial Checks:

   • Visually inspect your brake rotors for any obvious signs of scoring, deep grooves, or discoloration (blue/purple spots indicating overheating).
   • Check the thickness of your brake pads. While not directly causing pulsation, severely worn pads can contribute to rotor overheating.

2. Common Causes:

   • Warped Brake Rotors: This is the most frequent cause. Rotors can warp due to excessive heat from heavy braking, improper lug nut torque during wheel installation, or even manufacturing defects. When warped, the rotor's surface isn't perfectly flat, causing the caliper to push the pads against an uneven surface, leading to pulsation.
   • Uneven Pad Deposits: Sometimes, brake pad material can transfer unevenly to the rotor surface, creating high spots that mimic warping.
   • Sticky Brake Caliper: If a caliper piston or slide pin is sticking, it can cause uneven pressure on the rotor, leading to localized overheating and warping, or simply uneven pad wear.
   • Worn Suspension Components: While less common as a primary cause, worn wheel bearings, tie rod ends, or ball joints can exacerbate vibrations during braking.

3. When to See a Shop:

   • If you're unsure about inspecting your brakes or don't have the tools to measure rotor runout.
   • If the pulsation is severe or accompanied by grinding noises, which could indicate metal-on-metal contact.
   • Brake system issues are critical for safety. A professional can accurately diagnose if the rotors need to be resurfaced (if enough material remains) or replaced, and can check for other contributing factors like sticky calipers or worn suspension parts.