The DL501 transmission found in the C7 Audi S6 and S7 models is a great transmission, but as people are consistently pushing higher power and torque figures on higher mileage and older cars, the DL501 has began to show its weakness.
They often suffer from,
Mechatronic failures,
Clutch slippage,
Gear and synchro failure,
Bent shift forks
At Slavov Performance we have made a swap guide for anybody interested in swapping a 8HP55 into their S6 and S7, along with clearing up common questions and myths. The following parts list is what you will need
Transmission: You will need a ZF8HP55A (Any variant from a C7/C7.5 Audi A6/A7) We have commonly seen NNT and PPD code transmissions used for the swap without any issues
Rear Differential: You have 2 options for a rear differential.
1 – If your car natively has a sport differential, you can use a RS7 sport differential and either adapt component protection from the new differential to the vehicle. Or you can swap the sensors from the old S6/S7 differential to the new RS7 sport differential
2 – If your car natively has a regular differential or you would like to remove the sport differential you can use a matching NPR code differential, this differential has the correct final drive to match the new ZF8 transmission. If you are removing the sport differential you will also need regular differential axles (Part number 8R0501203C), if you already have a non sport diff, the existing axles will work
Shifter Cable: You can either replace just the shifter cable (Part number 4G0713265T) or the entire shifter assembly (Part number 4G1713105D), if you replace the entire shifter assembly you will also need to source an A6, A7, RS6, or RS7 shift knob.
Transmission Mount Bracket: You will need a matching ZF transmission mount (Part number 40399115G
Transmission Crossmember: You will need a matching ZF transmission crossmember (Part number 40399263G)
Transmission Hardware: You will need to swap and add the following bellhousing bolts
1 x M10 x 100mm bolt
2 x M10 x 60mm bolts
Transmission Cooler: You will need to install either an OEM A6/A7 transmission cooler, or add an external transmission cooler in the front side grille.
Optional Parts: Torque converter, a factory 3.0T torque converter will stall up to around 3200-3300rpm depending on the turbo setup on the engine side, a factory 4.0T or TDI torque converter is an easy upgrade. The 4.0T torque converter will stall up to around 4000rpm depending on the turbo setup, a TDI torque converter will stall up to about 4500rpm depending on the turbo setup.
Tools/ Applications Required
1 – Odis Service with Online Access (We will also cover how to do this swap without a need for Odis)
2 – Odis Engineering (We will also cover how to do this swap without a need for Odis)
3 – VCDS
4 – J2534 Cable compatible with Odis
5 – DS1 (We will cover how to do the swap without DS1 later in this guide, but we presume most will have DS1 already)
Below we will only cover the electronic side of this swap, if you need to, please see OEM VAG service manuals for mechanical instructions on transmission removal and install
Step 1 – Once you reach out to us for your initial binary file, you will need to full flash this file in DS1 before beginning any mechanical disassembly
Step 2 – Once the ZF8 is installed you will need to use Odis Service with online access to adapt the immobilizer of the new transmission to your vehicle
Step 3 – You will use Odis Engineering to flash a .frf file of the new RS7 firmware to your now adapted TCU, we will provide you with this file in our tuning service.
Step 4 – Once at this step please email us and we will get you in contact with DS1, they will change the supported firmware in DS1 to our recommended RS7 firmware dependent on if you have a C7 or C7.5 chassis, then you can update DS1 and email us the required files to begin the custom tune
Step 5 – Once you have received your new basemap from us, you will perform a full flash in DS1 with the basemap. Please make sure you do not flash any other file in this process as you may brick the ECU and require a bench recovery from us.
Step 6 – You will now need VCDS to apply long coding to each module that is uninitialized
Step 7 – As long as all major faults are cleared and the transmission is filled up to spec, you can use the instructions we have emailed you to flash your TCU tune, please select a stage applicable to your build. If you have any questions on what stage TCU tune to flash, please email us
Step 8 – Once completed, email us an idle log as mentioned in the email you received with the ECU basemap and we can begin the custom ECU tune.
Step 9 – Enjoy your ZF8 swap
How to without Odis but with DS1, if you do not have reliable access to Odis please follow below
You will have to remove and mail us your TCU out of the ZF8HP55 for bench flashing, then you will need to run our custom TCU tune that can be flashed at home directly through your portal using your standard TCU dongle, we have provided a link below. Please email if you have any questions (you still need to purchase a TCU tune)
How to without Odis and DS1,
Please email us as this is case specific and requires bench flashing both the ECU and TCU
If there are any questions about this process and the tuning/ programming services we provide, please email us at sales@slavovperformance.com
