Audi A6 A7 4K rear axle gear 09R500043B differential

Part Number: 09R500043B

Transmission Code: RPZ

Application: 3.0 TFSI (55 TFSI) / 3.0 TDI (MHEV)

The 09R500043B is a high-load rear axle final drive designed for the current generation (C8/4K) Audi A6 and A7 Sportback. This differential is specifically matched to the 3.0L V6 powerplants (both petrol and diesel variants) equipped with the 7-speed S-tronic or 8-speed Tiptronic transmissions and the Quattro with Ultra or permanent Quattro systems.

Technical Specifications

• Compatibility: * Audi A6 / Avant / Allroad (C8/4K): 2019–Present

  • Audi A7 Sportback (4KA): 2019–Present

• Final Drive Ratio: $44:10$ ($4.40:1$)

• Weight: Approx. 23.05 kg

• Engine Codes: Commonly paired with DLZA (3.0 TFSI) and various 3.0 TDI MHEV (Mild Hybrid) units.

• Gearbox Codes: Frequently seen in conjunction with the SCE gearbox.

Key Engineering Features

• Aluminum Housing: The casting is designed for high thermal dissipation and weight reduction, essential for the “Ultra” efficiency strategy of the 4K chassis.

• Low-Friction Bearings: Features specialized taper roller bearings designed to minimize rotational drag, contributing to the vehicle’s overall fuel efficiency and CO2 reduction targets.

• Quattro Integration: Works seamlessly with the electronic longitudinal clutch (in Ultra models) to engage the rear wheels in milliseconds when slip is detected or predictive logic requires AWD.

• Refinement (NVH): Engineered for ultra-low Noise, Vibration, and Harshness (NVH) levels to maintain the luxury cabin experience typical of the A6/A7 executive class.

Technical Installation & Cataloging Notes

1. Ratio Matching: It is critical to verify the RPZ code and the 44:10 ratio. Installing a differential with a different ratio will cause catastrophic damage to the center transfer case or transmission clutches as the front and rear axles will attempt to spin at different speeds.

2. Oil Specification: Requires Audi Genuine Axle Oil (G 052 145 S2). The capacity is approximately $0.9$ to $1.0$ Liters.

3. Drive Shaft Seals: When purchasing a used or “New-Old-Stock” unit, always inspect the output shaft seals for weeping. Replacing these before installation is standard professional practice.

4. Hardware: The mounting bolts for the rear subframe and the prop-shaft (Cardan shaft) are often stretch bolts. Audi technical manuals recommend replacing the prop-shaft bolts and the multi-point nuts to ensure they do not back out under high torque loads ($340\text{+ Nm}$ from the V6 engine).