Inside the Main Gearbox

Moving along with the disassembly steps in the workshop manual! The major components were separated; the goal now was to take a look at each and see what's what. In the previous post I took apart the main gearbox and broke it into its subassemblies. Now let's take a look at what condition they're in. 

In the gearbox there are two shafts: a mainshaft, and a layshaft. There are three forward gears with fourth being a direct-drive. 

Step one is using a punch to undo the nut on the end of the mainshaft. 

Of course there's a special tool for this nut. I'm also pretty sure literally no one bought it. 

The last guy in my gearbox sure didn't use the special tool, that's for sure! The lockwasher had broken tabs (only one was holding the nut on) and the shoulders were rounded where they'd been hit by a punch.

No big deal, I did the same thing. 🤷‍♂️

I started to take some of the pieces off and get a closer look at them. The grime and oily muck was everywhere. It's quite stuck on there: I had to take a wire brush to the oil thrower to clean it up. Some of the muck had left hard deposits on the components that couldn't be shifted without using the brass brush. Again, Simple Green worked well as a utility cleaner, along with lots of blue shop towels. Costco, my dudes!

The first thing you take off the mainshaft is the 3rd/4th gear synchromesh unit. I am by no means an expert on how this works: I took a cursory look at mine. It's apparent that a lot of the stuck-on grit is going to have to be cleaned off somehow, maybe with the ultrasonic cleaner. It *seems* to function okay? I'll have to check more closely at a later date and make sure the spring clip is robust etc. etc. 

1st gear has a pretty obvious chip / chunk taken out of it. 🙄 

It's not synchronized on this version of the LR gearbox, so someone probably jammed it in at some point and took a hunk of the tooth off. 

There's a fairly annoying spring clip that has to be removed. The angled pick tool I'm holding here is absolutely invaluable. If you don't have one, you need to get one: mine is used for everything from disassembly to scraping / cleaning, you name it. 

After a while you get to a brass distance piece that you need to remove to get the final gear off the mainshaft. Here's the distance piece as I found it:

... and this is what happened when I tried to lift it out:

Ooooooops. Pretty sure it's not supposed to be sheared in half. How does that even happen? Yikes. 

Hmm. Let's take a look at the condition of the gears themselves. I'm gonna make these pictures a bit bigger so you can get a better look at them: 

You can see wear on the main load-bearing surfaces on the gear teeth. It's easier to see where the light hits the surface on the right side of the gear, above. 

Same same with this one. Hmm. 

In addition to the wear, the mud / scale that's on everything in the gearbox is everywhere, even inside the oil passages and clinging to every non-contact surface. 

Hard to see in the right picture, here, but I was gently scraping it out of the inner surface of the gear. 

Hmm.