What we do on the 915 gearbox
Rebuild to factory specification
complete stripping, measurement and reconditioning — hypoid drive set up with original tooling, test-bench run at the end.8:35 final drive (i = 4.375)
the short RS/RSR ratio as a new part — teeth ground on drive and coast side to 0.0025 mm, serial-numbered, with measurement report and etched setting dimension. It replaces the 7:31, whose tooth spread at the pinion head is unfavourable — on almost every second gearbox it is damaged.Limited-slip differential
available for 18- and 43-spline shafts and for the variant with mechanical oil-pump drive — for the 915/72 with oil cooler coil, complete with Turbo stub axles; long unavailable from Porsche. We make the internals ourselves: planet gears, side gears and pressure rings with interchangeable set-up.Stub axle, 43 splines, Ø 109.90 mm
a direct replacement in original appearance — long discontinued by the manufacturer.Rotation-direction change
for mid-engine conversions, with fresh setting of the hypoid drive.
Typical problems this solves
- Crunching second gear — the 915 classic: worn synchromesh and dog teeth
- Howling final drive after an improperly set ring-and-pinion swap
- Worn stub axle with no original replacement available
- Standard ratio too long for hillclimbs or circuits
Buying a Porsche 915 gearbox instead of rebuilding yours
Not everyone wants to ship their own gearbox and wait for the rebuild. We keep restored gearboxes in stock — ready to fit and run on the test bench. Whether a 915 is currently among them we will tell you on request; we take your faulty gearbox in part exchange.
Available straight away is the 915 final drive with ground teeth, a measuring record and the etched setting dimension.
Why inquire here
We know hardly any gearbox better. From a single dog ring to the complete homologation-ready racing gearbox, everything for the 915 comes from one workshop — measured, documented, test-bench run.
What a rebuild finally costs depends on the findings. The range and the reasons behind it are in our guide What does a Porsche gearbox rebuild cost?.