Ford 8.8 question

I've finally got around to assembling my shortened explorer 8.8 everything went fairly smooth but now that it's together I have an odd issue. It will spin forward fine, no weird issue/noises/etc. The problem is when you spin it in reverse. It will be fine for say 310* of rotation then it gets very stiff. It will complete the rotation but require a fair amount of effort. There is no odd noise heard before or after this point.

This turning is by hand and the diff has no fluid in it right now. Running carbon clutch packs in the stock track-lol housing. 
 

Should I be concerned? Is this something that will clear up after adding fluid/breaking in the clutches?

Are the brake rotors and calipers on it?

In reply to Patientzero :

Yes. Same behavior before and after they were on.

Is the driveshaft connected too? Not trying to sound condescending, but it is worth asking!

If nothing is connected, I'd check the backlash at the tight spot, and 180° from the tight spot. You may find that there's a little bit of runout on the gearset/diff. 

Also, I assume you're turning the axles. Does it do the same thing if you turn it with the pinion yoke?

In reply to snailmont5oh :

Turning from the axles. It's less stuff when turning from the pinion

Lots of variables here. Did you change gears? Swap diffs?

Since turning from the pinion shows less resistance, the mechanical ratio is likely helping overcome the bind and the issue is further downstream.

Was the housing checked for straightness after shortening? What about the replacement short side axle? Interesting that the bind only shows up when rolling the parts in reverse, but the tolerance stack can certainly change with directional loading. 

I would start taking parts off one at a time until the bind goes away. Pull the axles and recheck, pull the carrier and recheck. Etc.

Have you over shimmed the trak lock? 

In reply to gumby :

Same gears and same diff. Axles are straight and so is the housing. 
 

Would it be possible it's just a very tightly shimmed diff? The old track-lol was very worn.