I'm rebuilding my front diff. The input pinion bearing went out because of lack of oil...long story...for another time... Decided to replace all the bearings and rebuild.
It's been a fun project with my kids and we're taking our time to learn about each step. They're pretty excited to get to drive this when we get it going again. We did the teardown together, they watched what I did on the drivers side and then did the passenger side themselves. We have everything apart and making progress getting it back together, I did my FJ80 diff rebuild a year ago so the steps are still pretty fresh. I wasn't going to pull out the differential gears, but my daughter noticed something didn't look the same on each side. Her curiosity (and good eyes!) saved us a headache.
The thrust washer under the big diff gear (is that the spider gear?) was broken. I found the missing piece in the bottom of the case. This doesn't look like it's part of the recent issue, it looks like it's been running this way for quite a while, the piece of the washer that was still in place is worn smooth and is complete enough to stay in place. None of the ring and pinion gears or diff gears show any sign of damage, although clearly, it got squished in gears at some point. Probably the chunk got caught up in a gear before it made it to the bottom of the case.
I can't imagine how this could have happened. I've owned this for almost 20 years and it wasn't driven much before I bought it. I did loan it to a friend for a few years, but he was almost all road miles, no offroading for sure, I don't think he ever even locked the front hubs. I off roaded a little, nothing too challenging. Is that washer under stress that might cause it to break apart? There's no sign it overheated. I think this truck was involved in a front crash early in it's life, maybe it was broken then. It just seems like an unlikely thing to break. These diffs sure are tough, to have a chunk like that break off and run though and keep on going for years! At least that's what I think happened.
I'm just glad we found it now rather than in a few days when we cleaned out the pumpkin for reinstall... Now I need to figure out what part to order, I hope I don't need to buy a whole new set of diff gears just to get that washer.
It's been a fun project with my kids and we're taking our time to learn about each step. They're pretty excited to get to drive this when we get it going again. We did the teardown together, they watched what I did on the drivers side and then did the passenger side themselves. We have everything apart and making progress getting it back together, I did my FJ80 diff rebuild a year ago so the steps are still pretty fresh. I wasn't going to pull out the differential gears, but my daughter noticed something didn't look the same on each side. Her curiosity (and good eyes!) saved us a headache.
The thrust washer under the big diff gear (is that the spider gear?) was broken. I found the missing piece in the bottom of the case. This doesn't look like it's part of the recent issue, it looks like it's been running this way for quite a while, the piece of the washer that was still in place is worn smooth and is complete enough to stay in place. None of the ring and pinion gears or diff gears show any sign of damage, although clearly, it got squished in gears at some point. Probably the chunk got caught up in a gear before it made it to the bottom of the case.
I can't imagine how this could have happened. I've owned this for almost 20 years and it wasn't driven much before I bought it. I did loan it to a friend for a few years, but he was almost all road miles, no offroading for sure, I don't think he ever even locked the front hubs. I off roaded a little, nothing too challenging. Is that washer under stress that might cause it to break apart? There's no sign it overheated. I think this truck was involved in a front crash early in it's life, maybe it was broken then. It just seems like an unlikely thing to break. These diffs sure are tough, to have a chunk like that break off and run though and keep on going for years! At least that's what I think happened.
I'm just glad we found it now rather than in a few days when we cleaned out the pumpkin for reinstall... Now I need to figure out what part to order, I hope I don't need to buy a whole new set of diff gears just to get that washer.
