2021-2025 Audi Q7/Q8/A8/S8 Noises/Vibrations TSB

Owners of 2021-2025 Audi Q7, Q8, A8, S8, SQ7, SQ8, RS Q8, and A8 e quattro models may experience noises and vibrations when driving through tight bends. This issue is addressed by Audi Technical Service Bulletin (TSB) 2074857/1, also identified by Service Number 3936.

This TSB clarifies that the complaint of Audi Q8 noises vibrations in tight bends is a comfort-related issue and does not indicate damage to vehicle components. The underlying cause is related to the self-locking center differential, specifically the Torsen differential, which can exhibit a 'stick-slip effect' under certain conditions.

Symptoms

Customers report experiencing "Noises/vibrations in tight bends." These symptoms are typically reproducible by technicians and are noticeably more pronounced compared to an identical comparison vehicle, especially when considering tire size and manufacturer.

Technical Background

Audi's all-wheel drive system, featuring a Torsen differential, provides dynamic power distribution without delay. However, under specific conditions—such as high speed in very tight bends—significant friction forces can arise between the worm gear flanks and the axial thrust washers in the differential. This friction can lead to a 'stick-slip effect', generating vibrations or a humming noise. This phenomenon is considered a comfort-related complaint and is inherent to the design, posing no damage risk to vehicle components.

Important Warnings

Audi explicitly states that this issue is "merely a comfort-related complaint." The described behavior is "construction-related" and "No damage occurs to components." Owners should not be concerned about long-term damage from these noises or vibrations.

Several other factors can negatively influence or exacerbate the Audi Q8 noises vibrations:

• Wheels: Differences in tire tread depth, hardness, width, or the use of summer versus winter tires, as well as variations between tire manufacturers (indicated by the AO code).
• Drivetrain Tension: Additional tension in the drive train, potentially caused by wheel alignment issues.
• Assembly Mountings: Noise transmission through various assembly mountings.
• Loose or Incorrectly Installed Parts: Noise generation or increase due to loose parts, parts under tension, or incorrectly installed components within the vehicle's interior or chassis.

Repair Procedure Summary

An improvement in the noises and vibrations can often be achieved by changing the gear oil in the transfer box. The degradation of the friction modifier within the oil, which occurs with increased mileage, can lead to a more pronounced stick-slip effect. Replacing the gear oil effectively replenishes this friction modifier.

For the repair, technicians must follow the precise approach detailed in the Workshop Manual. The full effect of the oil change will typically become apparent after driving approximately 60 miles (125 miles depending on the driving profile).

Before evaluating the complaint, the gearbox oil temperature must be between 40° C and 70° C (104° F and 158° F). Technicians should use a workshop tester to accurately determine the gearbox oil temperature, as higher or lower temperatures are not uncommon with this complaint.

Warranty Information

This Technical Service Bulletin (TSB) 2074857/1 outlines specific warranty claim procedures. If the vehicle is outside of its warranty period, this TSB serves as informational guidance only.

Field	Code / Description
Service Number	3936
Damage Code	0020
Labor Operations
Remove and install rear transmission mount	3738 19xx (See SRT with associated operations)
Replace gear oil	3990 5599 (50 TU)
Diagnostic Time
GFF	0150 0060 (Labor according to diagnostic log)
Charge battery	2706 8950 (See SRT with associated operations)
Extended road test after measure	0121 0199 (According to punch time, Max 200 TU)
Claim Comment	As per TSB 2074857/1

All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review by Audi Warranty.

Owner Action

If you are experiencing noises or vibrations in tight bends with your Audi Q7, Q8, A8, or S8 model, especially if it's a 2021-2025 model, it is recommended to visit an authorized Audi service center. While the issue is comfort-related and not damaging, a gear oil change in the transfer box, as outlined in TSB 2074857/1, may significantly reduce or eliminate the Audi Q8 noises vibrations.

---

Source: NHTSA ID: 10255909