issues with 4.89 axle swap

[markkish79]

Well unfortunitly I'm back with the same problem. I broke down the entire axle again and flipped the pinion double race and yet again when tightening the large nut on the yoke, it locks up completely. It won't turn at all with that much ft lbs on the companion flange nut. Does anyone have another idea what I am doing wrong here? This thing is driving me mad. Does it have to have 300 ft lbs on that nut? It was a 5.83, and I'm swapping it out for a 4.89. The

Any help much appreciated, Mark.

[markkish79]

Ok then. Well....I guess I'm on my own.

[isaac_alaska]

I would try and find contact info for Bob Stahl, as he's built more of these diffs than just about anyone here.

[ashyers]

As I stated in your prior post, current 4:89's require a different torque value.

[MSeriesRebuild]

To begin with, you should never torque the pinion shaft nut more than 160 Ft. Lbs., more than this you are dangerously close to breaking the shaft. Do you have the correct pinion bearing preload spacer installed? Are you aware that you should have all 8 spacers on hand before attempting to do this? It is the only way to know you will have the exact one you need. Are you attempting to do the set up correctly in that the middle bearing should not be in contact with its cup during set up? With this much said, if your answer to any of these questions is no, you are already headed in the wrong direction, and obviously you are not at all familiar with what it takes to set up this type of gear set correctly. First of all you need to have a thorough understanding of what must happen to do this job correctly. You also need the correct special tooling along with the expertise to use it properly in order to have a successful out come. Simply removing the old gear set and replacing with the new does not work. This really is not a procedure anyone can easily walk you through here, unless you already have more than basic knowledge of what needs to happen and the right stuff to work with.