GBOX LLC. Porsche and Getrag service-GEARBOX REBUILDING




ERIE, CO.  80516




Mon-Fri > 8am - 5pm MTN.

Sat-Sun > By Appointment.

GBox rebuild procedure

The GBox Porsche transmission rebuild process has four key steps:

  1. Disassembly

  2. Cleaning

  3. Machining/Blueprinting

  4. Reassembly

The Porsche transmission rebuild process starts with disassembly. This part of the process is a lot more important than most people would think.

  • This is an example of how the transmission usually looks when we start.

    930 gearbox before rebuild

    An untrained person trying to take apart a gearbox is simply trying to get it apart without breaking or damaging the parts. Often they do not accomplish this. Conversely, the experienced technician carefully and purposely removes parts of the gearbox in a sequenced order to determine its condition.

    A good technician will use this information to determine the level of service required. The level of service may range from very detailed inspection under a magnifying glass to just a quick check of how the part looks and fits.

    During the disassembly process measurements are made to determine the condition and setup of the gearbox. Certain key measurements include the ring and pinion R setting, differential bearing preload and backlash, and shift fork position.

    Checking these measurements is essential in determining if the gearbox has been serviced improperly during prior work or if certain components have become worn and are no longer within specification.

    Further disassembly allows the technician to examine parts for wear and to check the fit and finish of mating parts. During this stage the technician is looking to accomplish several things; sort out damaged or worn parts, verify and diagnose the customer complaint or gearbox problem, and begin to compile a list of parts needed for repair.



  • The next stage of the rebuild process is cleaning. During this stage all oil, grit, and foreign matter are removed from the individual Parts. This process allows the technician to double check that nothing has been missed during disassembly. Examples of problems found during cleaning include cracks in cases or gears, surface wear on bearing races, gears, shafts and other parts.



  • The machining and blueprinting process is used to correct permissable tolerance variations with individual parts or to enhance the function of the part. Often machining cannot repair a part and replacement is required. However, some parts can be machined to function properly without replacement. Examples of this include: surface grinding of spacers and shims for setup, straightening bent shafts, or milling warped surfaces flat. The primary benefit of being able to able to to machine and blueprint parts is that very precise setup is possible. The tolerance of the re-machined part will be much tighter than that of the original. A good example of this is the process of surface grinding spacers. The factory spacers are turned (lathe cut) and hardened; grinding the mating surfaces results in parallel and flat surfaces to within .0001/inch which is far better than factory.



  • The reassembly process is the final stage before the gearbox is reinstalled into the vehicle. At this time final fit and finish of each part is checked. The parts are usually put together in stages and individual subsystems are checked for perfect functionality (see 'Adjusting the 996 Gear Stack'). For example, the shift rails are assembled and detents are checked before reinstalling a case section or housing. Also, all tolerances and specfications are checked and the bolts are tightened to the correct torque.

    Please contact us with any questions about the rebuild process.