Causes of Automatic Transmission Shift Shock
3 Answers
There are many possible causes for harsh shifting in an automatic transmission. The main reasons include improper adjustment, degraded or damaged components, and faults in the electronic control system. Specific causes include: 1. High engine idle speed: Check the engine idle speed. For vehicles equipped with automatic transmissions, the standard idle speed is typically around 750r/min. If the idle speed is too high, it should be adjusted according to specifications. 2. Improper adjustment of throttle cable or throttle position sensor, leading to excessively high main circuit oil pressure: Inspect the adjustment of the throttle cable or throttle position sensor. If not within specifications, readjust accordingly. 3. Delayed upshifting: Check the vacuum hose of the vacuum-type throttle valve. Replace if cracked; reconnect if loose.
Driving an automatic transmission car and experiencing gear shift shocks is really annoying. I've been driving an SUV for five or six years, and common issues include transmission oil being too low or aged, insufficient oil leading to poor lubrication and sluggish valve movement; dirty oil clogging valve holes, causing hydraulic control imbalances and harsh gear shifts; excessive wear on clutch plates or brake bands leading to large gaps, especially noticeable at low speeds; faulty computer control modules receiving incorrect speed signals can also be a cause; and unstable engine idling can affect shift smoothness. It's best to regularly check the oil and filters, change the oil every 40,000 kilometers to avoid long-term problems, and pay attention to early maintenance to reduce shock damage, especially in city traffic with frequent gear shifts.
Having worked in an auto repair shop for many years, I've often seen shift shocks caused by hydraulic system issues. Unstable oil pressure could be due to leaks or oil that's become too thick from deterioration; clogged valve body passages are common when dirt buildup blocks oil flow; sticking solenoids or faulty sensors like the input shaft sensor sending incorrect data; worn clutch components or belts creating uneven clearances leading to shocks; and software program faults causing mistimed control. These situations can usually be resolved with oil changes and valve body cleaning, but severe wear requires part replacement. I recommend using genuine oil and regular inspections to prevent escalating costs and maintain driving stability.
