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The P633 gearbox is one of Xtrac’s legacy products, which whilst not currently in production, spares and technical support are still available upon request.

Xtrac’s ‘P633’ 4WD transmission has been designed specifically to cater for Rally cars competing under the FIA WRC & Super 2000 regulations, in series such as the Intercontinental Rally Challenge (IRC) and WRC championship, WRC & S-WRC.

The gearbox specification meets all the requirements of the FIA S2000 / WRC homologation regulations and has been approved for use in S2000 / WRC championships by the FIA. To meet the FIA’s requirements Xtrac has achieved the lowest possible costs, whilst ensuring a technically reliable and lightweight transmission solution built to its normal industry-leading quality standard.


  • 6 speed sequential
  • 450Nm (330lbf ft) maximum engine input torque*
  • Cast aluminium L169 casings
  • Adjustable mechanical type plate front differential
  • 50:50 fixed front/rear torque split.
  • Gearbox rear drive output shaft positioned for optimum vehicle and transmission package
  • Integrated oil system using an eccentric rotor pump
  • Dedicated gear change potentiometer, oil temperature & pressure and final drive speed  sensor mountings
  • Provision for individual wheel speed sensor mountings
  • AP Racing clutch release
  • Gearbox weight approximately 55kg

Gearbox Benefits

  • Light, positive sequential gear change
  • Optimised cluster to provide near instantaneous gear change
  • Easily removable cluster for ratio changes
  • Differential with externally adjustable pre load
  • Easily accessible oil filter cartridge
  • Designed for optimised drive shaft angularity
  • Cost effective, reliable, lightweight solution

Options Summary

  • Various driveline options
  • Prop shaft flanges to suit specific requirements
  • Various output flange options including AAR integral and plug in types. Integral speed sensor trigger as required.
  • Dog ring inspection ports.
  • Various options for reverse gear interlock
  • Bespoke gearbox casing design to include bell housing mountings, starter motor mountings and other installation specific requirements
  • Epicyclic or spur gear type final drive
  • Integrated oil system cooling
  • Starter motor
  • Flywheel

Find out more

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