Spider gears?

[Stinson]

What usually breaks spider gears? A fast spinning tire that gains traction suddenly? Just askin cause my brother has broken his spiders in both of his trucks. I know he drives like an ass but I am trying to figure out what the hell he is doing. The first was in a 02 2wd 4cyl ranger on 30's, and the next was in his 87 4x4 toy on 33's. Thanks

[Dred]

What usually breaks spider gears? A fast spinning tire that gains traction suddenly?

Yep, every time I've broken them, that was the cause!

[Billet Benny]

That shock load is very likely to break the weakest link. Sometimes, but not too often it is spider gears. One diff I know that does this is the 7.5" front diff in Tacomas. Some axles just tend to have the weak link as the spiders..

Beyond this, they're likely to fail if something isn't right such as missing or worn out thrust washers or a worn or out of place cross pin.

Chalk it up to weak diffs (both of those trucks have them) and make sure nothing is in a shape that promotes premature breakage.