Gearbox - Can’t engage reverse!

[geoffreyworthington]

I’ve just bought a Series 1, with a Series 2 gearbox. Reverse was working fine – until I got her home after a long journey. Now the gearlever will only push left against the spring, but won’t budge up into reverse (or down for that matter) at all. There’s no grinding, just the ability to move the lever laterally against the spring. It won’t then move up or down a single millimetre.

Any clues on what’s wrong and how to fix? I’m still waiting for the manuals to come through, so I don’t even yet know what the various parts are even called! Thanks!

[pjsank]

It might be something simple. My Series III occasionally will not go into reverse. I just verify it is in neutral, release the clutch, engage the clutch, and shift into reverse.

Will it shift into the forward gears now? Might by a clutch fluid issue.

[SafeAirOne]

If reverse doesn't move at all, I'd wonder if the other gears are fully in neutral.

Sometimes a worn shift lever will allow you to move the lever around as if you are in neutral even though one of the gear selectors are slightly out of the Neutral position.

The selectors are set up using a system of detents and a shuttle that makes it so that you can not move another gear selector at all unless the previous one is perfectly in neutral.

I'll try to post a photo of what I'm talking about...hold on.

[SafeAirOne]

http://farm8.staticflickr.com/7224/6863593618_c600a4b736_z.jpg

OK...Here's what it looks like under the gear selector cover on the top of the transmission. The end of the gearshift lever rides in those filthy slots on the left end of the three selector rods (the top slot is covered by the mechanism that makes the reverse position "spring-loaded". Reverse is the top rod, 1st/2nd is the middle rod and 3rd/4th is the bottom rod.

I've outlined in red, the shape of the shift rods in the area of the shuttles(those silver pellets between the rods). If the middle rod (1st and 2nd gear) is not exactly in neutral, the little shuttle can't fit into the detent in the middle rod when you try to shift into reverse. If the shuttle can't fit into that detent in the middle rod, you will not be able to move the top rod (reverse rod) at all.

The system is designed so that when you are shifting, at least one end of a shuttle has to be pushed into a detent to give the other selector rod enough room to slide by. This prevents 2 different gears from being selected simultaneously.

The pic above is pretty close to being in neutral (all detents lined up with the shuttles).

If the bottom of your gearshift lever is worn, it may be able to slide through the slots on the end of the shift rods without lining them up perfectly in the neutral position. A non-worn shift lever will not allow this to happen.

I'm not saying that this is your problem, but the shift lever is the place I'd start off when troubleshooting.

[geoffreyworthington]

Now it's starting to make sense - thank you so much for taking the time to explain and illustrate. I've taken the lever off today (it's looking worn) and I'll take the cover off the gearbox tomorrow - at least I'll know what I'm looking at!

[geoffreyworthington]

Thanks again for all your comments.

I took the top off. Now I understand exactly what you’ve been describing.

The reverse selector shaft will now run freely backwards and forwards with all the ball bearings and springs removed. They don’t cost much to replace, so I’ve ordered all new detent springs, ball-bearings, grommets, etc, and gear lever end o-ring. I’ll then just clean up all the parts, reassemble with a little Lithium grease around the ball-bearings and springs, and threadlock the threads.