Anyone know?

 

Not all of them are, but it is weird that so many are.

 

my guess would have to be because of the rotational direction of the driveshaft. It spins the same way as normal threading would, making it easier to become loose. Being reverse threaded prevents this from happenning. but again, this is just a guess.

 

Because it's really funny when someone doesn't know this and you hear them cursing from across the shop

 

As far as I knew, only fasteners which get torqued down in the center of a rotating part have the threat of working them selves loose such as a nut on a fan blade or balancer thats why the threads will be cut in the opposite direction as the rotational force. Now on a ring gear, the holes are on a bolt circle which have no threat of having a rotational force counteract their torque setting. In the GM 7.5 the ring gear bolts are a LH thread but in some DANA and Ford 9" rears I have seen I do not remember the ring gear bolts being reverse threaded. My only guess is that I know you can wedge a box wrench between the top of the houseing and a ring gear bolt and spin the yoke with a breaker bar to get the carrier out. I wonder if AAM actually took this into account when designing the rear or if there is another reason for it.

And oh yeah Im asking cause I snaped a head off the bolt with my impact the other day cause i forgot they were reverse threaded so - ha