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5 to 6-speed Trans Upgrade Kit For The Porsche® 928

See Videos of this part in action Product Installation Services Available

I'm happy to report that the return trip went great. Car and transmission performed flawlessly. The transmission completely changes the car - no pause between gears on up-shifts, quick down-shifts without double-clutching, and much better gear ratios for compatibility with the increased power from the supercharged engine. I used to be able to skip every other gear - 1st to 3rd to 5th. Now it's like having a transmission with twice as many useable gears and the right one for every situation. Also, running 80-85 MPH in 6th gear has the car loafing along at only 2,000 RPM which has to improve the mileage, although I didn't analyze that yet. Pete D.

Application: 1978-95 Porsche® 928 with Manual Transmission

Description: A bolt in replacement transaxle kit for the Porsche® 928, replacing the expensive and hard-to-find Porsche® 928 5-speed with the stronger and less expensive T56 trans from the Chevrolet Corvette. The transaxle can be installed stock or upgraded, and parts are plentiful. With readily-available upgrades to the Chevrolet transaxle, the transaxle can be made to hold 1000 lb ft of Torque.

At this time, we are only using the 2001-2004 C5 ZO6 manual transaxle with this kit. In the future, we may be able to use the standard 1997-2004 Corvette C5 (non-ZO6) and the later C6 transaxles and torque tubes.

The Porsche® 928 independent rear suspension and brakes are maintained, so you will not loose any performance nor 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. It is stronger than the aluminum section we removed. 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. Your old transmission has 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 FDR to a 3.42:1 FDR, with a significant 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 aluminum torque tube
  • Shortened and balanced custom drive shaft
  • 928MS custom half-shafts (axles)
  • 928MS custom splined driveshaft section
  • 928MS transaxle support with mounts
  • 928MS custom rear cross-member
  • 928MS custom shifter mount and shift rail
  • Installation instructions

Automatic-to-Manual Conversions: This kit can also be used to convert a 928 with automatic transaxle into a manual trans car. One of the largest expenses of such a swap has always been finding and acquiring a good used Porsche 928 transaxle. You also need the 928 torque tube, flywheel, clutch assembly, bell housing, and pedal assembly. Good used Corvette 6-speed transaxles are much more plentiful and less expensive (and more fun!). With the parts we supply in this kit, the actual 928 items you need to buy to finish the swap is limited to only the clutch and clutch pedal systems.

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.






5 to 6-speed Transaxle Upgrade Kit For The Porsche® 928



Ships in 4 weeks or less

* 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