Just more info in relation to lockers and diffs for the T4R...which I pulled from Toyota120forum. as written by Andries (Bulldog).
"Here is some more interesting info and something to keep in mind. As some of you know there has been a number of Tacos and FJC with rear lockers that have grenaded their rear diffs. Upon further investigation some guys in Europe and a number in Oz (without lockers) have also grenaded their rear diffs. What happens is that the actual ring and pinion strip the teeth off.
James was able to find a nice write up by Darren McCae in Oz, he runs ats4x4 and is well respected in modding Toyotas. Pretty much the "go-to guru" in Oz for Toyota 4x4 mods.
He describes the problem as follows:
"If you want to make the rear diff stronger, and stop the crownwheel flexing
away from the pinion, leaving the teeth unsupported, you need to fit an ARB
locker, which has a much stronger hemisphere, and no hole in the side of the
carrier to get the side gears in, and the diff needs to be set up with a
solid
pinion spacer, rather than the crushable type it comes with.
These mods won't prevent abuse breaking it, but they make the diff as strong
as
it can be.
And if you get the new crownwheel and pinion from Toyota under warranty, rather than a whole new diff, which can do the same thing, it will allow you to have the mods done to strengthen it."
So far it he has not seen any failures after doing this mod on the Prados in Oz, which means it is probably the way to do it to make the rear end last. This is actually funny as previous gens used to grenade the front, Toyota beefs it up and now the rear goes. Still a lot of unanswered questions surrounding the failures though, so we shouldn't get into a panic mode (at least the solution is clear).
Also remember we have not seen any failures on the STOCK setup in the 4Rs in the US. Prados are heavier than the 4R and also the Oz guys tend to load them up more ( long expeditions), so the rear carries a lot more weight. However the 4R has a V8 with a 5spd auto, so the combination of the V8 and torq. converter and low 1st gear will put more torque on the rear than either the PRado, Taco or FJC. So I would recommend when you open the rear to make it as strong as possible.
Looking at Darren's recommendations, it seems the best way to go when regearing is to put the ARB in. Also to get the solid pinion spacer. I got some advice from the Nrocal 80 LC guys for an installer that seems to do this. The guy is based in Sacramento (Sean Eskilsen (owner) at River City Differentials 916-852-7109). He carries a good rep with the Cruiser guys, which is a good thing."
Dan,
If you are installing the ARB lockers - you may really want to consider this sage advice in relation to the pinion spacer vs crushable washer.
Has 4WP done this? If not you might want to discuss it with them. It seems like a very necessary part of the installation process.
Certainly in the past we have heard of a recent increase (heresay) of diff's breaking and this (info above) seems to reinforce it - the heresay that is.
Cheers
Mark