I happen to have my son's '78 sitting in my garage, and a couple of manuals that go with it. One manual is a Haynes that covers from '63 thru '83.
What I read about the right end of the crankshaft is this: "The cranshaft pinion (gear) is also difficult to remove without Triumph service tool Z121. The chief danger is the risk of damage to the end of the cranshaft whilst the pinion is being drawn off; extreme care is necessary. If the Triumph service tool is not available, the pinion can be left in place until the crancases are separated. It can then be removed by driving the crankshaft through the right side main bearing with a rawhide mallet. This method is recommended only if the main bearing concerned is due for replacement." (This bold print is in the manual.)
Do you have the gear off the end of the crank? If so, I can only guess that the bearing inner race is "stuck" on the crank, which probably will require that above mentioned rawhide mallet to be used on the end of the shaft.
Are you sure you have to pull the crank out of the case half? Sleep on it and look at it again later. Maybe you'll see a way around this.
If you use gasoline to flush out the case half, be sure to do it outside so the fumes don't get to an open flame source (like your gas water heater), or accumulate in an enclosed room/garage. The let the case set (outside is best) while the gasoline evaporates. You could also use a spray can of carb cleaner to blast out any sludge. Be sure to wear some eye protection while doing that one!
GOOD LUCK from PapaDean.
