Morris Minor Owners Club

my gearbox has been jumping out of gear in second on overrun which I'm told is probably due to worn synchromesh ring. I've tried loading a photo but the website won't let me despite having resized ( others have had this issue) can any one describe any visual difference between a new and worn synchromesh?

Tried attaching a photo again this morning, working now - think the website troll just needed a lie down

Hi

The jumping out of gear will have nothing to do with your syncro ring being worn or not, the syncro ring is to help it go into gear.

The problem will be the dog teeth on the 2nd gear wheel being worn, once they lose their shape and have sloping sides, then it tends to push the 1st gear ring away from it on the over run and pop it out of mesh.

Phil P

Thanks Phil, I've been told by various people over the years that the jumping out of gear in overrun was worn syncro, but I was always sceptical. Below is the second gear, how worn is this?

It is difficult to say looking at your photo in isolation, it will also depend on the mating 1st gear ring being in good nick as well.
Have a look at how the two parts mesh together as a pair.
Also the amount of end float of the gears on the shaft will have a bearing on how well it works.

Now you have the box in bits it is difficult to know how well they were meshing when it was running.
what causes the gear to jump out is when the dog teeth have worn so that there are sloping surfaces in contact with each other and that causes an axial force to push them apart, if the detents are a bit worn on the selector shafts that might also allow some movement that should not be there.

Phil