Homologation-Ready Motorsport Gear Sets

The 8:35 final drive for the 915 gearbox

The short final drive with ratio i = 4.375 – ring and pinion as fitted to the 911 RS and RSR (Porsche reference number 915 302 911 02). Newly produced in Germany on modern gear-cutting machinery – a faithful 1:1 reproduction of the original.

The quality shows on the tooth surface: ground on drive and coast side to a tolerance in the region of 0.0025 mm, not milled and lapped to a price. Every set is serial-numbered and delivered with a measurement report; the setting dimension for optimum running is etched into the pinion face. The matching high-tensile crown-wheel bolt kit is included.

Homologated gear pairs in stock

For the 901, 904, 906 and 908 gearboxes, homologated gear pairs sit finished in stock – including the Nürburgring ratio – and ship immediately. All details on the dedicated page: homologated gear pairs.

Nine final drives in stock

We machine top-quality final drives not just for the 915 gearbox. For the 356, 901, 904, 906, 908, 908/03, 915, 916 and 917, finished, ground final drives sit in stock ready for immediate delivery – the 356 final drive with a 12-hole mounting. Each type has its own detail page; the overview is at final drives in stock.

Gear sets and racing gearboxes

Beyond the final drive we produce:

• Gear sets in various ratios+

  For building historic racing gearboxes – homologated gear pairs for the 901, 904, 906 and 908 including the Nürburgring ratio are in stock. Which spacing fits depends on the track and the regulations – short ratios for hill climbs and tight courses, longer ones for fast circuits. Tell us the series and how the car is used, and we’ll match the gear spacing to it.
• Final drives for other gearboxes+

  Such as the 7:31 for the Porsche 356 gearbox. The same production quality applies as for the 8:35: ground teeth instead of milled and lapped, serial-numbered and with a measurement report.
• Ready-to-install special gearboxes+

  Fully built, set up and test-bench run – 904 and 906 complete gearboxes sit in stock ready to install, every fitted part available individually as a spare. You do not receive a box of parts to assemble but a gearbox that only needs bolting into the car – including documentation of the settings.
• Dog-engagement layouts (dog box)+

  For pure racing use. Without synchro rings, shifts are faster and cause less wear, but the shift action is unpleasant on the road. We advise openly whether the conversion pays off for your use – often a reworked synchromesh is the better answer.

Combined with our limited-slip differential, this adds up to a complete, homologation-ready drivetrain package from one workshop – gear cutting, differential, setup and test bench under one roof.

Setting up is part of the job

A precise gear set is worthless if backlash and contact pattern are wrong. That is why we offer installation including setup to factory specification – with original setting tools, contact-pattern check and a final test-bench run. If you install it yourself, the documented setting dimension ships with the set.

Advice to suit your regulations

Historic motorsport means the rulebook has a say. Whether FIA Appendix K, Histo Monte or hill climb – tell us where you race, and we will tell you which ratio and setup fit.