4:1 Center Differential Upgrade

The JH Motorsports 4:1 Center Diff Upgrade is engineered for Audi B6-B7 S4 and B7 A4 models equipped with the 6-speed Tiptronic transmission. This upgrade modifies the center differential to achieve a 4:1 torque bias ratio, similar to the stock RS4, enhancing performance in twisty driving conditions and reducing understeer under throttle. It is specifically recommended for Auto-Crossers and Road Racers who prioritize cornering grip. Installation requires refilling approximately one quart of 75w90 synthetic gear oil, which is sold separately. Buyers have the option to send their existing differential for modification to avoid a core charge, with same-day modification and shipping often possible. Alternatively, a core unit can be provided, with a core fee refunded upon return of the original differential, provided it is not damaged. It is common for this modification to result in a slight chatter during low-speed U-turns, particularly when not under power. This is an expected characteristic due to the altered bias under load and at higher speeds, and is generally not noticeable during normal daily driving. Purchasers must acknowledge that this product is intended for off-road use only and may not comply with emissions standards for public roads, agreeing to indemnify JH Motorsports against any liability arising from its use on highways.