My gearbox has a very "crunchy" 3rd/4th gearchange which indicates a worn synchromesh cone. To replace the cone it is necessary to remove the 'box from the car and very nearly completely strip it. To ensure I can do the job, I have practiced the job on a scrap gearbox donated to me by a member of the 205gtidrivers forum.
The following is how I determined the best way to strip and rebuild the gearbox before doing the job for real.
The following are required in addition to normal car servicing tools to successfully strip and rebuild the 'box:
A set of pin punches to extract and replace roll-pins
A 5/8" Whitworth or 11/16" BSF bi-hex socket
A large hide mallet
A flat bearing puller
A large two-legged puller
In addition, two special tools have to be made, one to retain the ball and spring detent in the 5th gear selector fork and a mandrel to replace the input shaft end bearing without damage. Both can be easily made in a small lathe
Give the exterior of the gearbox a very thorough clean. Not only is it a lot nicer to work with a clean gearbox but it also minimises the risk of dirt ingress during the strip and rebuild. Dirt and gearbox internals do not mix well.
When cleaning, bung up the driveshaft holes and the speedo drive with rags to prevent dirt ingress.
Prepare a big space on a sturdy workbench and clean up your working area.
Beware that a gearbox is heavy. Mind your back when lifting!
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Page last updated 05 January 2010