Jammed gearbox

[cadetchris]

So I’ve got around to putting the gearbox and engine back in the car. I’ve come to put the prop shaft back on and i discover that the gearbox has seized/jammed.
When I took it out the car, it worked and and all I’ve done to it is to replace the scroll seal in the bell housing for a modified seal version and replace the tale shaft seal, other than that and a paint, it worked fine.

The gear stick will move to the right side of neutral but you cannot engage any of the gears. The engine turns over freely by hand, but I just cannot get it into gear?

Any ideas?
Slightly loathed to remove the engine and gearbox again as it look an age with just me doing it.

[philthehill]

Did you store the gearbox on its end i.e. resting on the bell housing?
If you did there is the possibility that crud or a rogue part has found its way into the gear mesh so stopping you selecting a gear.
The Morris gearbox should be stored in a horizontal position to alleviate the possibility of crud fouling the gearbox parts.

[cadetchris]

It’s been stood on either end and on any side, particularly during a house move at the beginning of the year.
In hindsight, I should on d of checked that it was free before i bolted it to the engine and manhandled it back into the car.
Guess I’ll spend Sunday taking it out of the car and checking what’s going on on the inside….at least it won’t snow again.

[Chipper]

I had this problem with a ribbed-case gearbox I hastily assembled, and it turned out to be a missing indent plunger for one of the selector forks; it would select reverse and a forward gear at the same time, leaving the car unable to move!

I was able to unjam it (temporarily) by removing the oil drain plug (obviously, draining the oil first!) and wiggling a long screwdriver in there to free off the stuck fork.

[myoldjalopy]

One possibility is "broken gear shafts, but more likely due to the engagement of two gears at the same time due to a defect in the gear engagement mechanism" This from the very useful Minor 1000 Repairs by B C MacDonald. Sounds like this was the 'defect' in Chipper's case...

[cadetchris]

I’ll have a look in the covers tomorrow and see if any thing has fouled up. Hopefully it’s just a simple fix as the gearbox worked perfectly fine before I took it out the car.

[cadetchris]

Well I found what it was that was jamming the gearbox, but what is it?

[philthehill]

Part of it looks to be either the shim from the first motion shaft Pt No: 10G143/144/145 or shim from the third motion shaft Pt No: 10G186/187/188. Part number from Charlie Ware catalogue.
I cannot make out what the other bits are - a couple of photos on a different plane may help.

[Chipper]

Looks like an old gasket possibly from the remote linkage, or rubber bung that usually goes in the bellhousing...
Whereabouts was it jammed into?

[cadetchris]

It was amongst the levers for selecting the gears. I am pretty sure it’s part 10G144 from the first motion shaft.

[cadetchris]

It’s a bearing packing shim from the output shaft, within the gearbox extension (ribbed gearbox)
So I’ve ordered a new one and I’ll fit it on Friday. I just need to figure out the technique to re-engage the control lever with the shifter rod selectors

[philthehill]

As regards the packing/shim - there are three thicknesses of packing/shim - make sure that you get the right one.

[cadetchris]

I’ve ordered 1 of each. Once I get them I’ll bounce check the thickness with the remnants of the original one.

Is there a particular knack to getting the selector to engage with the selector rods?

[jaekl]

Many say you don't need to, but I loosen the outboard selector, (I think it's 1-2) so the fork can be rotated to create a opening for the selector to pass.

[cadetchris]

That was thinking, loosening off a shaft would allow me to get it on.

[cadetchris]

So the new packing shims have arrived.

But what are they actually for? I understand what they do but I struggle to think why the need to be there.