07-03-2019, 11:02 AM
Sometimes the synchro teeth (the fine teeth) wear, especially if the box was used with gritty oil in the 1950's. This can, especially if the adjustment is a bit out, cause an end thrust, which will cause a jump out of gear.
Also, excessive end float in the gears on the third motion shaft can cause problems; usually the bronze bush between the gears is worn in this case.
A clue to these more serious problems is gained by observing when the "jump out" occurs, if the lever "drops" out mildly when decelerating, blame the selector springs. If it "hurls" out under power, its usually end float or worn synchro teeth in my experience.
Also, excessive end float in the gears on the third motion shaft can cause problems; usually the bronze bush between the gears is worn in this case.
A clue to these more serious problems is gained by observing when the "jump out" occurs, if the lever "drops" out mildly when decelerating, blame the selector springs. If it "hurls" out under power, its usually end float or worn synchro teeth in my experience.