SIIa first and reverse gear gone

[warrenperkinson]

In heavy traffic today my first gear started making a terrible knocking sound.

I managed to get off the motorway only to discover that reverse has the same problem. All other gears, including low ratio and the overdrive work fine.

I managed to limp home using low ratio instead of first…

So I'm guessing that the gearbox will need to come out. Any ideas as to what I'll find? Do you think the gearbox will be salvageable or should I start looking for a replacement?

[cedryck]

Start with a drain of 90w. See what kind of potential bits come out. If you had a loud noise, and loss of gear, then you most likely will need to open it up, and inspect, and replace fowl parts, not as hard as it sounds, I never did ANY transmission before, and rebuilt my series 2 box with sucessfull results.

[warrenperkinson]

I drained the oil and below is a picture of what I found. Without question this is a gear tooth...

So I've now pulled out the seats, floor and gearbox tunnel in preparation for pulling the gearbox and rebuilding...

Are sIIa gearbox parts still available?

[I Leak Oil]

Given that 1st and reverse are gone, you'll probably find the first gear on the layshaft is gone. The bearing on that end is not the most robust and could well be the root cause.
You cans till get parts. Make sure you know what suffix box you have and try to get genuine or NOS if possible. I wouldn't order anything until you get it open and figure out what you need. There will likely be more than just a gear. Bearings and seals are always a good idea, especially if this is the first time the box has been apart.