Less celebrated than the 911 but every bit as significant, the Porsche 928 is one of the manufacturer's iconic series, thanks to its radical design and engineering innovations. Produced from 1978 to 1995, it was the first Porsche to feature a V8 engine, and the first to mount it at the front. Despite this layout, the Porsche 928 gearbox remains positioned at the rear axle, connected to the engine by a rigid shaft — the famous torque tube. EDEN BOITES is here to help you maintain and repair this distinctive transmission.
A V8 engine that evolved
Over its seventeen-year production run, the 928 underwent several facelifts that advanced its mechanical specification. The earliest models, with a 4.5-litre V8, produced 240 bhp. From 1984, the 4.7-litre V8 raised output to 310 bhp. In 1992, the final redesign introduced a 5.4-litre V8 producing 350 bhp, in the GTS variant.
The two gearboxes of the 928
Throughout its production life, the 928 was fitted with a five-speed manual gearbox, the G28, which remained fundamentally unchanged despite minor revisions. It operates on the same principles as a conventional manual gearbox, but the distance between the gearbox and the engine, combined with the transaxle layout, demands complex mechanical linkages and cabling. The cables run the full length of the vehicle, which could affect gear-change precision; Porsche's engineers therefore paid close attention to this linkage to prevent flex and slack. Alongside this, a four-speed automatic Mercedes-Benz 722.3 was available as an option; torque-converter-based, it shares the characteristics of the transaxle architecture.
Keeping the gearbox maintained
The transaxle configuration calls for careful attention to the cabling, which must be monitored to prevent wear, as well as precise linkage adjustments. To minimise wear, keep the transmission fluid at the correct level, top up the oil as needed, and have the fluid changed approximately every 100,000 kilometres. Regular inspection by a specialist also allows for a general wear check and timely replacement of any components showing fatigue.
Repair guidance
Repairing the manual or automatic gearbox on the 928 is no straightforward task. Access is awkward: the vehicle must be raised and securely supported on axle stands. The next step is removing the gearbox, after disconnecting all wiring and the driveshaft — the latter sometimes requiring complete disassembly. The components can then be inspected for damage, wear or leaks; any faulty parts are replaced and the assembly is rebuilt, with particular care taken over the precise calibration of the torque tube. A final test confirms correct operation. This procedure is complex, owing to the rear-mounted position of the gearbox and the scarcity of certain parts, and is best entrusted to a specialist.
Opting for replacement
When the gearbox is too badly damaged or a part is simply unobtainable, replacement is the only option. For further reading, take a look at our guides on the Porsche 968 gearbox and the Porsche 924 gearbox, two other transaxle models. Our article on the differences between manual and automatic gearboxes provides a useful complement to this overview. All our references are listed in our gearbox catalogue.
Frequently asked questions
Which gearbox does the Porsche 928 use?
A five-speed manual G28 throughout its production life, with a four-speed automatic Mercedes-Benz 722.3 available as an option.
What is the torque tube?
It is the rigid shaft that connects the front-mounted engine to the rear gearbox in the transaxle layout. Its calibration must be perfect following any work on the transmission.
When should the 928's gearbox fluid be changed?
A transmission fluid change is generally recommended at around 100,000 kilometres, adjusted according to usage.
Repair or replace?
If the gearbox is heavily worn or a part is unavailable, a reconditioned exchange gearbox is a reliable and long-lasting solution.
Why choose EDEN BOITES?
EDEN BOITES specialises in reconditioned gearboxes sold on an exchange basis. Every gearbox is stripped, cleaned, inspected and tested by our experts before dispatch. With EDEN BOITES, you benefit from a warranty of up to 24 months, the option to pay in up to 10 instalments, and delivery throughout France and the European Union, with lead times confirmed on quote. Our exchange gearboxes are offered with a satisfaction or money-back guarantee, subject to our Terms and Conditions. Check your vehicle's reference, then browse our gearbox catalogue to find the right unit for your Porsche 928.
