These are my impressions and lesson I learned from the re-gearing project. It is not intended to start another self promoting boring and somewhat annoying discussion as what is better, the 80 or the 100, and the like. I think this is a new info and I tried to be as factual as I can. If it’s not, please accept my apologies.
Front –
Easy, above and beyond the ARB locker stuff no issues.
Rear -
Order the carrier bearings for a locked diff. The installation kit of the gear manufacturer (Precision in my case) comes with bearings for the unlocked diff, which are smaller. I ended up using all Toyota parts. Also the set-up shims are larger.
The threads on the after market (Precision Gears) rear pinion are smaller then the Toyota’s. There are the same as the front’s, so order 2 nuts that fit the front pinion.
The 80’s carrier case cover bore is smaller then the 100’s and the axle shaft would barely go through so you either machine the 80’s (need to take ~50 thousands) or use the 100’s. Since the body and the cover are a matched pair, I decided to machine the 80 cover. I did not want to risk carrier bearing premature wear problem due to misalignment issues. Also, the bore on the other side (the carrier case side) is smaller then the original (100) but is plenty large for the axle shaft to go through, so I left it alone.
You cannot use the side gears washers of the 100 as they are too large. The mating machined surface is smaller in the 80 carrier case and cover. In the 100 case it’s larger and has oiling tunnels to better lubricate the thrust bearing (plain) area.
Ok – To the ring and pinion themselves. According to MY (AND ONLY MINE) inspection and superficial (VERY) analysis, I would draw the conclusion that the 100 ring-and-pinion set up is slightly stronger then the 80. The ring teeth are wider and also have more contact area. It is actually on both, the ring and the pinion (it has to be). Again, I don’t know by how much and I don’t know if it significant enough to make a difference, but it is stronger. Just to put it in perspective, the fact that you go from 4:30 to 4:88 has more impact on the ring-and-pinion strength (negative) then the difference between the 80 and 100 set up.
I am not quit done but this is what I learned so far.
BTW - There are noticeable quality differences between the Toyota gears and Precision’s. Bummer but nothing I can do about it now.
Front –
Easy, above and beyond the ARB locker stuff no issues.
Rear -
Order the carrier bearings for a locked diff. The installation kit of the gear manufacturer (Precision in my case) comes with bearings for the unlocked diff, which are smaller. I ended up using all Toyota parts. Also the set-up shims are larger.
The threads on the after market (Precision Gears) rear pinion are smaller then the Toyota’s. There are the same as the front’s, so order 2 nuts that fit the front pinion.
The 80’s carrier case cover bore is smaller then the 100’s and the axle shaft would barely go through so you either machine the 80’s (need to take ~50 thousands) or use the 100’s. Since the body and the cover are a matched pair, I decided to machine the 80 cover. I did not want to risk carrier bearing premature wear problem due to misalignment issues. Also, the bore on the other side (the carrier case side) is smaller then the original (100) but is plenty large for the axle shaft to go through, so I left it alone.
You cannot use the side gears washers of the 100 as they are too large. The mating machined surface is smaller in the 80 carrier case and cover. In the 100 case it’s larger and has oiling tunnels to better lubricate the thrust bearing (plain) area.
Ok – To the ring and pinion themselves. According to MY (AND ONLY MINE) inspection and superficial (VERY) analysis, I would draw the conclusion that the 100 ring-and-pinion set up is slightly stronger then the 80. The ring teeth are wider and also have more contact area. It is actually on both, the ring and the pinion (it has to be). Again, I don’t know by how much and I don’t know if it significant enough to make a difference, but it is stronger. Just to put it in perspective, the fact that you go from 4:30 to 4:88 has more impact on the ring-and-pinion strength (negative) then the difference between the 80 and 100 set up.
I am not quit done but this is what I learned so far.
BTW - There are noticeable quality differences between the Toyota gears and Precision’s. Bummer but nothing I can do about it now.
Just letting it be known that this has been covered.
