Why are my gears notchy?
QI’ve replaced the gearbox on my Morris Minor. The box was rebuilt some years back and little-used.
All the gears seem to function correctly, except that some are a bit stiff to disengage. They go in easily enough but I have to bat the lever a couple of times with the palm of my hand to get it back out. I found that if
I back off the throttle at the same time it pops out OK. Reverse is stiff to go in and also has to batted back out. But unless I mis-time it, there is no crunching involved during the changes, up or down. Does it just need using, to wear it in?
Mike Hockey, Mansfield
Matt says
ASome gearbox designs are naturally a bit ‘notchy’ although it’s not a characteristic you’d attribute to a Minor. Backing off the throttle is a bit of a clue to what might be wrong. It implies that there’s still some drive to the gearbox even though the clutch is notionally disengaged. Does the car try to creep forward while the clutch is pressed? Clutch drag usually has two causes. First is that the pressure plate of the clutch is not being lifted sufficiently by the mechanism and continues to put moderate pressure on the friction disc and flywheel. This might be a simple adjustment issue: wear in the linkage; wear or bending of the clutch release arm or severe wear of a carbon clutch release bearing. Was a new friction disc put in while changing the gearbox? Maybe it’s slightly too thick; this will wear in soon enough, especially in town driving. The final possibility is that the spigot bush in the end of the crank is unlubricated or damaged, or that the spigot on the end of the gearbox input shaft is very slightly imperfect in some way – corroded, oversized, bruised, crushed or bent. Other than checking basic clutch adjustment, our advice would be to see if the problem improves over the next thousand miles or so. Slightlymismatching components might bed themselves to each other during this time. The fact that it doesn’t crunch into first or reverse is a good sign. The easiest way to remove a spigot bush, incidentally, is to pack it with grease and hammer in a closefitting metal rod or input shaft from a scrap gearbox. The grease forces the bush out.