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Automatic to 6-speed Trans Conversion Kit For The Porsche® 928

See Videos of this part in action Product Installation Services Available

Application: 1978-95 Porsche® 928 with Automatic Transmissions

Overview: Many owners of Porsche® 928s wish that their car had a manual transmission instead of an automatic. The manual transmission provides a more sports-car experience, and acceleration is enhanced dramatically to near-supercharged levels because of the new gear ratios. But, one of the challenges to this conversion has always been finding and buying a good used Porsche® 928 5-speed manual trans. Using the 928 Motorsports 5-speed to 6-speed kit, we skip the Porsche® 5-speed and jump right to the M12/T56 6 speed which are more plentiful, stronger, and less expensive. All 928 parts and instructions are provided, you only have to source your own used Corvette parts (and we will provide a shopping list for you for those items).

The Porsche® 928 independent rear suspension and brakes are maintained, so you will not loose any performance or your investment in 928 brake and suspension upgrades. You will still use them.

The Porsche® 928 clutch and flywheel is also maintained, so you will still be able to service your clutch without removing the engine or transmission. The 928 Motorsports aluminum flywheels and performance clutch packages are compatible.

The center section of our cross-member is made from mandrel bent 4130 Chrome Moly tubing. The two outer sections of our rear cross-member start from actual Porsche® 928 parts, and then are sectioned and modified as needed for our application. This way we are able to use the original suspension mounts provided by the OEM cross-member, making certain that all our rear alignment and suspension mounts are correct. As an added plus, this 3-piece cross-member design also allows you to remove and service the transaxle (if that should ever be needed) without removing the rear suspension.

Easy Shifting: You will enjoy the upgrade to smooth, easy shifting that this kit will provide too. The stock 928 manual transmission had brass synchro rings (heavy) and the new 6-speed transmission has carbon-fiber synchros (light). They react faster, engage more smoothly, and do not require double-clutching during up-shifts or downshifts. Your shifts will be glass-smooth all the time, making performance driving simpler and more fun.

Better Acceleration: The acceleration of your 928 will be much more brisk after the 6-speed is installed because of the lower final drive ratio (FDR) of the ZO6 trans. Most 928's will be going from a 2.20:1 or 2.54:1 FDR to a 3.42:1 FDR, with a matching increase in acceleration as you would expect. Yet, because of the 6th gear overdrive, the engine is not laboring at highway speeds either.

Kit includes:
  • Customized Corvette aluminum torque tube
  • Shortened and balanced custom drive shaft
  • 928MS custom half-shafts (axles)
  • 928MS custom splined driveshaft section
  • 928MS trans-axle support with mounts
  • 928MS custom shifter mount and shift rail
  • New 928 clutch master and slave cylinders with lines
  • New clutch kit with throw-out bearing
  • Steel or (optional) aluminum flywheel
  • Used 928 upper and lower bell housing, clamping sleeve, and stub shaft
  • Used 928 clutch release fork
  • Used master cylinder bracket with rivets
  • Used 928 pedal assembly
  • Installation instructions

Modifications Required: This is an advanced kit that will require significant skill to install. For example; the firewall on the automatic transmission car has to be modified to hold a clutch master cylinder. We will show you how, and provide the needed parts - but it will require skills with a hole saw and riveting to install the clutch master cylinder mount. Alternatively, you may bring the car to us for us to perform this conversion for you.

Two ways to install: We can ship the kit to you so you or your mechanics can install it. Or, you can send your 928 to us and we will install the 6-speed transaxle and kit for you. When the installation is finished, customers usually fly in to Milwaukee airport and we pick them up there in their own car and they drive it home. Call for pricing if you are having us do the installation.

What to send us: Whether we are installing it or you are, you still need to send us some of your Corvette parts so we can modify them. You need to supply us with your:

  • C5 ZO6 Corvette Torque Tube
  • C5 ZO6 Corvette driveshaft
  • C5 ZO6 Corvette shifter mount
  • C5 ZO6 Corvette shifter linkage

Each of these items will be modified by us and returned to you for use in your 928.

If we are installing the 6-speed for you, you also need to supply us with your C5 Z06 transaxle with differential.

OPTIONS: You have a few options when you order.
  • MOUNTS: Our kit is designed to use either polyurethane mounts for street-driven cars without roll cages, and solid mounts for racers and cars with roll cages. Just tell us which you prefer. The cost is the same.
  • DRIVESHAFT COUPLERS: We can assemble your driveshaft into the torque tube with the stock rubber driveshaft couplers for maximum vibration isolation and ease on your drivetrain parts. Good up to 500 HP. Or, we can assemble it using one or two solid couplers, great for racing, and good to 1000 HP. There will be an upgrade of $165 for each solid coupler installed.
Fitment Notes:
  • Exhaust: Some 928 exhaust systems will require modification to clear the rear of the new differential if they currently cross over from the RS to the LS behind the differential.
  • Speedometer: The 1991-1995 Porsche® 928 draws the speedometer pulse from ABS system, so the speedometer will continue to work as before on these cars. On 1978-1990 cars, the pulse generator is located in the differential cover so you will need to buy and install a GPS pulse-generator to make your speedometer work again if that is your wish.

Special Order Item: This is a Special Order item, custom-made after you order specifically for year and model of 928. There are no returns allowed on Special Order items.

Core Charge: A $100 refundable core charge for the rear cross-member will be added at checkout and will be refunded when we receive the stock rear cross-member


Part Number




Automatic to 6-speed Transaxle Conversion Kit For the 1978-1986 Porsche® 928




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Automatic to 6-speed Transaxle Conversion Kit For the 1987-1995 Porsche® 928




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++ A $100 refundable core charge for the cross-member will be added at checkout

* Domestic US shipping shown. International shipping will be calculated based on location.


Phone: (920) 485-0928
Email: info@928motorsports.com

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Horicon, Wisconsin USA

928Motorsports.com - Performance Parts for your Porsche® 928