OK, now a little background...
I bought this gearbox back in ~2012 from a guy who was putting a 2JZ in a 4x4 mintruck. He was in the military and bought the gearbox in the early 90's. He had it sitting in his garage in Virginia beach ever since then. 20 something years later he decided that it was time to clean the shop out. I found this ad and had it shipped to California to replace the W56's i kept blowing up in my TDI converted minitruck. Anyone who knows these trucks knows this is the holy grail of minitruck gearboxes.
After getting it here in CA I found a transmission shop to rebuild it. I really didn't want to rebuild it my self because I had a studio apartment and I had gave away all the tools I needed to do it months earlier when I moved to CA from NY. I dropped all the parts off to the guy and to the best of my knowledge he replaced them all. after handing him ~1000$ I picked up my shiny new looking gearbox. Right away I noticed it was loud at idle. I decided to throw some heavy rear end gear oil in it to quiet it down. It worked but then it shifted like ass. I brought the truck to his place (keep in mind this is right after I got it running) and he told me I ruined the syncros by putting heavy oil in it. I thought to myself, well this is possible so I'll just change the oil to the recommended viscosity and deal with it.
Fast forward 5 years and I started its project with the FJ40. I pulled the gearbox apart and changed the input shaft. At the same time I changed the syncro ring for 4th gear. I noticed that the syncro was the wrong part for the trans- thats why 4th always sucked. I threw the thing together in the mad rush that im always in and boom it shifted great in 4th. Second gear had always been s***ty since the rebuild but I didn't feel like tearing that far into it in my dads garage in NY (while under pressure to get the truck out of there).
Now fast forward another 2 years or so until today. I tore this thing all the way down. I found heavy pitting on many of the bearing surfaces. This type of corrosion happens when over time the oil film disappears between the two parts when they are not moving.
When you have surface failure at the same spacing as the rollers as shown in this failure I have it is likely due to corrosion. See the following picture:
This is a textbook example. Here's a snip from a web article:
I also measured excessive runout on several of the locations where the backlash was never properly set causing additional wear and fretting. This was especially the case where the 5th gear installation was performed. I provided the parts for this gear set, but he never took the measurements to properly install them.
So here I am doing the job finally 7 years later
I'm not going to tell you how to rebuild a gearbox but here are some pictures:
