Case Study: Transmission Jerk in a Mercedes Benz GL
Vehicle: Mercedes Benz GL With 9G-TRONIC
Customer Complaint: The vehicle experienced a transmission jerk while in the “D” (Drive) range.
Initial Investigation
The main issue reported was a transmission jerk occurring during driving. Upon reviewing the vehicle’s service history, it was noted that the Vehicle Gear Selector (VGS) had been replaced previously. However, no fault codes were detected during the initial QUICK TEST.
To further investigate the transmission jerk, we lifted the vehicle and removed the under guard to check for any Automatic Transmission Fluid (ATE) leakages, but no signs were found.
Test Drive and Diagnosis
A test drive covering approximately 25 km was conducted with a senior technician. During the test, a gear jerk was observed between 70-120 km/h during both upshifts and downshifts, confirming the presence of the “transmission jerk.” Both technicians suspected that the adaptation of gears might not have been done correctly, which could be causing the issue.
Standstill Adaptation Procedure
Given that the transmission jerk was not severe, we decided to perform a Standstill Adaptation. This involved securing the vehicle’s wheels with anti-wheel spinning lockers. Following the XENTRY instructions, the brake pedal was fully depressed, and the accelerator pedal was pressed from position ‘0’ to the Kickdown stage.
After completing the Standstill Adaptation, another test drive was conducted. No further gear jerks were observed, indicating that the transmission jerk issue had been resolved. To ensure the fix was effective, an experienced Master Technician performed a final test run, and with no issues detected, the vehicle was cleared for return to the customer.
Conclusion
The transmission jerk issue in the Mercedes Benz GL was successfully resolved through the Standstill Adaptation process, eliminating the need for a Running Adaptation.
Transmission shudder repair
“Transmission shudder” is a common issue in vehicles with automatic transmissions, characterized by a vibrating or shaking sensation, especially during acceleration or when the transmission shifts gears. Here’s a general guide on how to address and repair transmission shudder:
1. Diagnose the Cause
- Transmission Fluid: The most common cause of transmission shudder is old, dirty, or low transmission fluid. Contaminants in the fluid can cause improper lubrication and friction, leading to shuddering.
- Torque Converter Issues: A failing torque converter can cause shuddering, as it may not be able to efficiently transmit power from the engine to the transmission.
- Worn Clutches or Bands: Worn internal components in the transmission, such as clutches or bands, can cause shuddering during gear changes.
- Driveline Issues: Problems with the driveshaft, universal joints, or CV joints can sometimes be mistaken for transmission shudder.
2. Transmission Fluid Replacement
- Fluid Change: If the transmission fluid is the culprit, the first step is to drain and replace it with new, manufacturer-recommended fluid. In some cases, a transmission fluid flush may be necessary to remove contaminants.
- Additives: There are specific transmission additives designed to reduce shuddering by enhancing the lubrication properties of the fluid. These can be added during the fluid change if appropriate.
3. Torque Converter Inspection and Repair
- Inspect: If fluid replacement doesn’t resolve the issue, the torque converter should be inspected. Signs of torque converter problems include excessive shuddering at low speeds or when accelerating.
- Repair or Replace: Depending on the severity of the issue, the torque converter may need to be repaired or replaced. In some cases, a remanufactured torque converter may be installed.
4. Transmission Overhaul
- Internal Inspection: If the shudder persists, a more in-depth inspection of the transmission’s internal components may be necessary. This involves checking the clutches, bands, and other components for wear and damage.
- Rebuild or Replace: If significant wear is found, a transmission rebuild or replacement may be required to fully eliminate the shuddering.
5. Addressing Driveline Issues
- Check Driveshaft and Joints: Ensure that the driveshaft and joints are in good condition, as issues here can mimic transmission shudder.
- Repair or Replace as Needed: Repair or replace any worn or damaged driveline components to ensure smooth operation.
6. Reprogramming or Adaptation
- Software Update: Some modern vehicles may require a software update or reprogramming of the transmission control module (TCM) to correct shuddering issues.
- Adaptation Procedures: For vehicles with adaptive transmissions, performing a transmission adaptation or reset procedure can help resolve shuddering.
7. Test Drive
- Verification: After repairs are made, perform a test drive to ensure that the shuddering issue has been fully resolved.
8. Regular Maintenance
- Preventative Measures: Regular transmission fluid changes and inspections can help prevent shuddering issues from occurring in the future.
Addressing transmission shudder promptly can prevent further damage to the transmission and ensure smooth and safe driving.
More information in the next link ; Mercedes 9G Tronic Oil Change : All Information Here
How often transmission service ?
The frequency of transmission service can vary depending on the type of transmission, the vehicle manufacturer’s recommendations, driving conditions, and the type of fluid used. Here’s a general guide:
Automatic Transmission Service
- Regular Service Interval: Typically every 30,000 to 60,000 miles (48,000 to 96,000 km).
- Fluid Change: It’s generally recommended to change the transmission fluid and filter within this interval. Some manufacturers suggest fluid changes every 60,000 miles, while others may extend it up to 100,000 miles for certain models with “lifetime” fluids.
- Severe Driving Conditions: If you frequently tow heavy loads, drive in extreme temperatures, or do a lot of stop-and-go driving, you may need to service your transmission more often, around every 30,000 miles (48,000 km).
