2021-2025 Audi Q8 Noises/Vibrations in Tight Bends TSB

Audi has released Technical Service Bulletin (TSB) 2074859/1 to address customer reports of continued noises and vibrations when driving in tight bends. This issue affects various Audi models, including the 2021-2025 Audi Q8, Q7, A8, S8, SQ7, SQ8, RS Q8, and A8 e quattro. The TSB clarifies the nature of the complaint and outlines the steps technicians should take to resolve it.

Symptoms

Owners may notice "noises/vibrations in tight bends" during vehicle operation. These can manifest as a vibration or hum, which may cause other components in the vehicle to resonate. The primary complaint is the presence of these distinct noises and vibrations when the vehicle navigates sharp turns.

Important Warnings

Audi explicitly states that this issue is considered a "comfort-related complaint" and that the observed behavior is "construction-related." Crucially, "No damage occurs to components" as a result of these noises and vibrations. Owners should be aware that if their vehicle is outside of its warranty period, this Technical Service Bulletin is for informational purposes only, implying potential costs for diagnosis and repair.

Several other factors can negatively influence or exacerbate these noises and vibrations:

• Wheels: Differences in tread depth, hardness, width, tire type (summer or winter), or tire manufacturers (AO code).
• Drivetrain: Additional tension in the drive train due to improper wheel alignment.
• Mountings: Possible noise transmission from assembly mountings.
• Interior/Chassis: Noise generation or increase due to loose parts, parts under tension, or incorrectly installed components within the vehicle's interior or chassis.

Diagnosis and Technical Background

When diagnosing the "Audi Q8 noises vibrations tight bends" issue, technicians are instructed to first reproduce the customer complaint to ensure it aligns with the TSB's scope. The underlying cause is related to the Torsen differential, a permanent all-wheel drive system used in these Audi vehicles. While the Torsen differential offers superior driving dynamics, specific conditions can lead to the reported noises.

In very tight bends, especially at high speeds, significant speed differences between the front and rear axles can create extremely high friction forces within the differential's worm gear and axial thrust washers. This high friction can result in a "stick-slip effect," which generates the noises and vibrations experienced by the driver.

Repair Procedure Summary

Technicians should follow a two-stage repair process for the "Audi Q8 noises vibrations tight bends" concern. Initially, they must follow the procedure detailed in TSB 2074857. This initial TSB addresses preliminary measures to resolve the issue.

If the measures outlined in TSB 2074857 do not resolve the customer complaint after the vehicle has been driven approximately 60 miles, a more extensive repair is required. The next step involves replacing the center differential. This replacement should be performed according to the instructions found in ETKA (Electronic Parts Catalog) and the Workshop Manual (Elsa).

Specific labor operations associated with these repairs include:

• Removing and installing the rear transmission mount: Labor operation code 3738 19xx (if not billed under TSB 2074857).
• Replacing gear oil: Labor operation code 3990 5599, estimated at 50 labor units (TU) (if not billed under TSB 2074857).
• Removing and installing the propshaft: Labor operation code 3902 19xx (if concern persists after 60 miles following TSB 2074857).
• Removing and installing the Torsen differential: Labor operation code 3936 1999, estimated at 90 TU (if concern persists after 60 miles following TSB 2074857).
• General removal and installation of the Torsen differential (GFF): Labor operation code 0150 0060, with labor time determined by the diagnostic log.

When a new differential is installed, its positive effect is partly attributed to friction modifier additives. These additives are concentrated at the friction surfaces and will gradually mix with the MTF (Manual Transmission Fluid) over time, helping to restore the expected vibration levels to normal.

Warranty Information

For warranty claims related to TSB 2074859/1, the Service Number is 3936 and the Damage Code is 0020. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review by Audi Warranty. The claim comment should specify "As per TSB 2074859/1."

Owner Action

If you own a 2021-2025 Audi Q8, Q7, A8, S8, SQ7, SQ8, RS Q8, or A8 e quattro and are experiencing noises or vibrations in tight bends, it is recommended to contact your authorized Audi dealership. Describe the symptoms to them, referencing TSB 2074859/1, so they can perform the necessary diagnosis and repairs according to the outlined procedures.

---

Source: NHTSA ID: 11009937