This vehicle came into our shop with differential failure, ring and pinion melted down. The story behind it is, this vehicle had initially developed a leak at the differential axle seal that had gone unnoticed by the owner until it started making noise from the low fluid condition. The owner of the car took it to an nearby repair facility to replace the seal and to refill the differential with the proper lubricant. Unfortunately, the facility that took on the repair may have been somewhat under-qualified. When the customer got his car back it was no longer leaking but the noise seemed to be getting increasingly worse. It wasn’t very long before the car wouldn’t pull at all.

At that point, we got the call to tow it in and do the rebuild. Of course, when we opened the differential portion of the transmission we found a pile of scrap metal (no teeth at all left on the pinion). When we opened the trunk to store the undercovers we found a differential shim in the trunk. We believe this may have been left out of the differential when the axle repairing shop finished their job. This suspicion was confirmed when we tried to stack the replacement ring and pinion back together with the existing shims from the defective unit.

Ultimately, we transplanted the transfer gears, planets and clutch carrier from the original transmission code HCP into the donor A6 core code HHZ. The donor unit had a good case and perfect ring and pinion gears as well as the correct shim set up. Of course along the way, we installed a master overhaul set, new chain and the new factory recommended update for this CVT transmission which includes 7 clutches instead of the original 6.

One thing every reader should take away from this repair blog is to take your car to a repair facility specifically qualified for your vehicle every 20,000 to 30,000 miles and have it properly checked for leaks. Don’t let a little oil leak turn into a major repair for you. Of course if you are in the Dallas Fort Worth Texas area, just call the service desk for an appointment to service your Audi CVT (Continuously Variable Transmission).