[Mark42]

Originally Posted by alamantia

whats the difference? The gears dont need break in,
Yes, they do need break in. Its part of the wear hardening process specified by the popular gear manufacturers.

they are ran at the factory and are heat treated to 50+ rockwell, there is nothing that wears off of them.

Most gears have a dark grey coating on them. Its a phosphorus compound designed to assist with the wear hardening. It wears off and contaminates the oil. That's part of the reason the oil is dumped after the first 500 miles.

Perhaps minimal clutch dust from the posi if its even a clutch style and there is a magnet for metal debris on the stock cover, if you upgrade to a TA cover its worse for the rear because if there is any debris its nit being collected by teh magnet, its floating around the assy. Clutch and cone stuyle posis like eaton and auburn usualy require mineral oil with friction midifier, worm gear posis work well in synthetic or mineral. Either way no break in is necessary.

The Eaton Truetrac indicates that there is a break in period and the vehicle should be driven lightly avoiding shock loads for the first 500 miles.

There is nothing you can do to upset the gemotery of heat treated hypoid gears. The only possible factor is if you use new bearings the preload is a few inch lbs higher so that when the rollers seat in the races the preload drops. New bearings may give off a little more heat until they seat. Thats about it.

Just added a few comments to your post that needed clarifying.

Regards,

Mark