What Causes Body Vibration When Braking in D Gear?
2 Answers
Reasons for body vibration when braking in D gear: Slight vibration is normal, but severe shaking may indicate damage to the engine mounts. The engine mounts, typically made of rubber, connect the engine to the chassis and help absorb engine vibrations. When the car is in D gear with the brakes applied, the transmission fluid inside the torque converter flows at high speed and is subjected to significant shear forces. Prolonged operation in this state can cause the transmission fluid temperature to rise, leading to increased fuel injection by the engine due to higher load, resulting in higher fuel consumption and elevated engine temperatures. Keeping the car in D gear with the brakes applied for extended periods is detrimental to both the engine and transmission. D gear, also known as the drive gear, engages the corresponding forward gear hydraulic circuit based on throttle position and vehicle speed signals when the gear selector is in this position.
With over 20 years of auto repair experience, I often encounter customers complaining about vehicle shaking when braking in D gear, which is mostly caused by multiple mechanical issues overlapping. The most common culprit is a faulty torque converter in the transmission, leading to uneven power delivery—especially noticeable when transmission fluid is dirty or low in older vehicles. The engine side also shares responsibility: worn or cracked engine mounts reduce vibration damping, allowing idle vibrations to transfer directly to the chassis; ignition system faults like carbon-fouled spark plugs or leaking coils can destabilize engine RPMs and worsen shaking. Even minor brake drag or caliper issues amplify vibrations when braking. My advice: immediately check transmission fluid level/condition for cloudiness or darkening, and manually inspect engine mounts for hardening. Neglecting these accelerates damage—prompt professional diagnostics can prevent costly overhauls. Adopting regular transmission fluid changes significantly extends vehicle lifespan.
