Installing the Drive Side mainshaft bearing into the gearbox casing is a tricky job.
For starters, the bearing housing is recessed behind the "trap door" in the primary chain case, making inserting the bearing very awkward.
Also, consider that our fingers are not made of asbestos and the bearing housing has been thoroughly heated to around 100C.
Finally, to achieve success, the bearing must be presented perfectly square to its bore in the case.
Here's a little trick that overcomes all the obstacles: use an old (or new, if you're careful) mainshaft as a "stick" to insert the bearing into it's bore. Very simple, very effective!
(Click Photos to Enlarge)
Have a suitable drift ready to drive the bearing all the way home if necessary. A digital thermometer is handy for knowing when the casing is hot enough - around 100C (212F). As an alternative, use the "sizzling spit" method.
Once the casing has been heated up, insert the bearing over an old mainshaft and use the mainshaft as a handle to present the bearing to the casing.
Often, the bearing can be pushed all the way in just using the mainshaft, but if necessary use a "suitable drift" (such as the one pictured in the previous photo) to drive it all the way home.
Job Done!
