The concept
The differential works on the proven ZF principle: pressure rings with defined ramp angles compress a clutch pack as soon as drive torque is applied. The result is a repeatable, serviceable locking action – no electronics, no special oils, no surprises.
Configurable are:
Locking value from 25 to 75%
Matched to application and driving style. Low values stay benign on the road; high values give traction on gravel and when powering out of tight corners, but make the car push more on turn-in. We recommend the value from your actual use, not from a catalogue.Separate ramp angles for drive and coast
This lets the behaviour under acceleration be tuned independently of the behaviour on lift-off. A strong drive side with a restrained coast side is the usual circuit setup – in rally use it often looks different.Preload to your specification or our recommendation
Preload determines how much locking is present before any torque is applied. It calms the car at the limit but costs some manoeuvrability at parking speeds.Friction linings of the inner plates
In several variants, depending on the characteristic and service life you want. The lining choice decides how consistently the differential works over a race distance and at what interval it needs a refresh.
Material and quality
Every load-bearing component is made from high-grade CrMo steel, weight-optimised and machined in-house. The internals – pressure rings, side gears, plates and shafts – are ZF-compatible. That means we can also recondition an existing original ZF unit using our parts.
The differential is competition-proven – rally, circuit, hill climbs and historic events such as the Histo Monte – and suitable for building homologated historic racing gearboxes.
Available from stock
For eleven gearbox types — 901, 904, 906, 907, 908, 910, 911, 912, 914, 915 and 917 — reproduction clutch-type differentials sit finished in stock, matched to the Porsche original in layout and mounting dimensions. For the 930 and 935 we supply differential and axle flanges.
Service for existing units
You do not need to buy a new differential to benefit from this workshop:
Complete overhaul of your existing unit
Strip, measure, replace worn plates and pressure rings, reset. Because all internals are individually available here, a refresh is predictable and considerably cheaper than buying new.Setup conversion to a different specification
Different locking value, different ramp angles or changed preload. Anyone changing how the car is used – road to circuit, circuit to hill climb – rarely needs a new differential, just a different setup.Spare parts for every internal component
Plates, pressure rings, side gears and shafts are supplied individually. That makes maintenance calculable – particularly in racing, where wear is predictable and deadlines are not negotiable.Maintenance and adjustment, including installation
On request we fit the differential into the gearbox or axle unit you send us and set up the ring and pinion afresh. Manufacture and installation then sit with one workshop – nobody points at anyone else if a question comes up.
Steel differential for the 356
For the 356 gearbox we machine a steel differential with a 12-hole crown-wheel mounting – the durable foundation for uprated 356s at 110 to 150 hp. Together with the 7:31 final drive, uprated axle shafts and a tall 4th gear, the differential is also available in the 356 complete package.
One-off builds
For vehicles outside the standard programme we build limited-slip differentials as one-offs – from a drawing, a sample or a supplied pattern. From taking the measurements to the ready-to-install differential, everything stays in one workshop.