OK - Finally got the chance to sit down and prep the photos of the OBX diff. I've been holding off, in part, because one of the diffs was defective (cracks in the case) and I wanted to get it replaced under warranty. I just received the replacement diff on Thursday and its in good shape - inside and out. I have to say that I've learned my lesson on inspecting parts THOROUGHLY as soon as they arrive. The eBay seller only gives you 7 days to return parts. However, the seller exchanged the defective diff long after the deadline... after I explained that OBX was not responding to my emails and faxes. The exchange actually went smoothly. In hindsight, I think OBX and the 3 ebay sellers are either one in the same business... or very closely networked. But getting to the point, I figured it was wiser to wait to post pics after the exchange was done... just in case the sellers stumbled upon this thread (opening the diff voids the warranty, as does the installation in a non-approved vehicle ... what do you mean this ain't no Miata?!? <img src="/forums/images/graemlins/scared.gif" alt="" />).

Now for the pics...

Here's the diff, fresh out of the box...




Another view showing the ring gear mount...




Here's the case - opened up and gutted. The internal machining is crude and dirty - lots of metal shavings left from the tapping of the holes for the case bolts. But that can all be cleaned up...




Here's a layout of the internal components...




Belleville washer comparison - The Chinese washers are known to be of poor-quality and should be replaced, along with the case bolts. I bought 2 kits of washers & bolts, as noted earlier, to replace the Chinese parts. You can see in the photo that the stock washers are ugly. But they also lack "spring" and have failed in some diffs (don't forget that this diff is only $279 U.S. - a little elbow-grease, some bolts & washers, and this diff might roll a tank!)...




Sun gears showing circlip grooves...




These are the components that form the "spring assembly". Its basically the belleville washers stacked between two splined-retainers, which sit in an internally-splined housing. The outside of the housing is grooved to receive the helical satellite-gears...




This is the spring assembly in its assembled-state. Note the height created by the washers - compressing the stack creates preload on the sun gears...




Here's a photo describing the proper-orientation of the sun gears. This is critical for proper-functioning of the differential...




This is the "don't do it like this" orientation...




Here's my "trying to make sense of it all" diagram. This shows the relationship of the internal components as they would interact within the case. Basically, the pinion turns the ring gear and case to provide forward-travel. The helical-planetary gears are, in turn, rotated by the case - turning in the opposite direction of travel. The planetary gears subsequently-turn the helical-sun gears in the forward-direction, which are splined with the axles...

[img]http://i999.photobucket.com/albums/af117/peabody1986/Sportage/OBX%20Diff%20Project/OBXDIFF11-1.gif[/img]


(NOTE: I had to edit the photo and the description below... got my thrust directions reversed... what you see now is correct... I think <img src="/forums/images/graemlins/baby.gif" alt="" />)

I still don't understand how this design provides limited-slip, or torque-distribution (it might not really slip... not much, at least). What I do understand is that the planetary gears thrust laterally and internally against the diff case (away from the wheels) when under the load of forward-travel. That's why the orientation of the sun gears is critical: you want the sun gears to thrust away from the belleville washers. Get it wrong and you grind up your washers while you drive because the axles/sun gears continuously-compress the washers. Now here's where I get lost... when the torque-bias reaches the threshold-ratio (not sure what it is for the OBX, or if it is even a static value), the planetary gears on the side with less-torque get pulled outward - away from the center, pulling the low-torque sun gear towards the belleville washers (I think)... while the high-torque side retains the normal-positioning. And somehow during that action, the torque is distributed to the wheel with better traction. As long as there is some torque on the low-traction side, you will get some percentage of torque delivered to the traction-wheel. However if the low-traction side spins freely (i.e. is in the air), then no torque is delivered to the traction-wheel (zero torque X a bias ratio is zero - or zero torque delivered to the wheel on the ground). The simple fix for that is to lightly-touch the brake while driving - the drag of the brake returns some torque to the low-traction wheel, and X-times more torque to the drive-wheel. I just don't understand how the gears slip or slide to transfer torque unequally... there's not much room in the case for them to move much more that a millimeter, or maybe a few. <img src="/forums/images/graemlins/confused.gif" alt="" />

Jump in if you can explain... <img src="/forums/images/graemlins/shiner.gif" alt="" />