Peabody, thanks for the update.

Not to hijack the post, but your signature says you have a 3" body lift. Your bumpers look like they have been relocated too. What did you do to get a 3" body lift and how did you relocate your bumpers?

Nice Sportage too!!!

Logansportage <img src="/forums/images/graemlins/patriot.gif" alt="" />

No worries about hijacking. The Sporty was lifted when I bought it. The seller had a set of 3" body blocks fabricated at a machine shop. For reasons not quite clear to me, he opted to get a 3.5" suspension lift from Everet, then lift the body 3". The suspension lift is perfect. The body blocks seem fine. But I don't know if they have recesses to keep them in place. I haven't noticed any signs of shifting. But some of the rubber pads seem to be a bit off-center. That noted, I haven't noticed any issues with the vehicle's handling that would be associated with the lift job. The only issue I have is that the body lift really threw off the geometry of the transfer case's shift lever. Now the lever has to slide under the lower-right corner of the tranny shifter to engage 4-low. In fact, I couldn't get it into 4L without trimming about 1/2" of threads off the TC lever. Now I need to fabricate a horizontal extension to offset the lever being under the console while in 4L. I almost had it fixed last weekend. But my extension was just a wee-bit too long, which prevents the TC lever from staying in 4H - it keeps popping back up towards 2H. Sooooooo close, yet so far away... <img src="/forums/images/graemlins/shiner.gif" alt="" />

Oh yeah - the bumpers have not been altered. Perhaps the low-angle of the photo makes them look off... or maybe the 3" body lift??? I'm dying to replace the factory-plastic with some kind of steel bumpers, to include a winch on the front. I've been looking at aftermarket bumpers for the Jeep Wranglers and Toyota pickups. I have yet to compare the dimensions and mounting points between them and the Sporty to see if either will work. I've also thought about fabricating my own. But I know they'll probably look like garbage. But if they do the job... <img src="/forums/images/graemlins/cheers.gif" alt="" />

A close up pic of the body lift block would be nice to see if you could post.

Also, they would have had to move the bumpers up or you would have a 3" gap between the top of your bumper and the body.

A picture of how your bumpers are mounted would also be nice.

Logansportage <img src="/forums/images/graemlins/patriot.gif" alt="" />

I spent a bit of time over the weekend beating on the front fenders and wheel wells so the beefy tires wouldn't rub (problem solved). I had to trim some of the front bumper off too, and noticed there were two metal tabs that have been added to connect the lower-portion of the bumper to the frame. I will take a picture of it and post it soon, along with the body lift.

As for the OBX diffs, I tore one of them down and took some photos, which I haven't been able to post yet because I tore down my computer for a home-renovation project. Once the PC is back together, the photos will be posted. I did find that the OBX diffs are the bare-minimum of manufacturing, though I can see how they can still be strong and hold up to the horses. There were lots of metal bits around the tapped holes and some rough-machined edges to boot. That doesn't surprise me though, because that correlates with others that have opened up the OBX diffs have found. If you want them to last, then a good cleanup of the rough spots and replacing the case bolts & belleville washers is pretty-much a must. Again, the pics will come soon. That concludes my report... <img src="/forums/images/graemlins/patriot.gif" alt="" />

OK, just posted pics of the stock bumper-mod and the front body-blocks on my winch bumper thread.

I have photos of an OBX diff disassembled. I want to add some comments to (in) the photos before I post them so they'll make more sense... or add to the confusion??? <img src="/forums/images/graemlins/zombie.gif" alt="" />

Thanks for the pics and info. I posted comments on that page.

Logansportage <img src="/forums/images/graemlins/patriot.gif" alt="" />

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="" />

Well, you think that you understand something and then you come to find you're wrong again...

I found a video on YouTube that shows how the Eaton TruTrac differential functions to distribute torque. It is another helical-gear design, but only uses 3 helical-planetary gears per side (they call them "pinions"). The essence of the design is the same as Quaife, OBX and the Type-2 Torsen. And it all comes down to this - The planetary gears don't rotate when the torque bias is equal between the two sides (50%:50%). Once the ratio changes, the planetary gears begin to rotate. And though the planetary gears for both axles mesh in the center of the differential (common to all designs mentioned), they somehow allow the axles to rotate at different rates... which appears to be all based on torque and the pitch of the helix (changing the pitch apparently changes the torque-bias ratio [TBR]). So it might not really involve "slip" - at least not in the same sense as you find in a clutch-based diff.

Also, I don't think the spring-effect of the belleville washers is critical to the function of torque-distribution. After doing a bit more research, I came across some posts that claim the first Quaife diffs didn't have the spring-stack. They were added to eliminate the annoying sounds caused by the sun gears rattling in the case during turns. Again, it is important to orient the sun gears so they thrust away from the spring assembly "naturally", when under the load created by forward travel.

Here's a link to the clip on YouTube... The demonstration of the torque-split starts around 1:20 min in the video.

Eaton TruTrac video


Here's another clip that shows how the T1 torsen works...

T1 Torsen clip


Oh, you can't leave out the Lego model of the T1 Torsen...

Lego Model of T1 Torsen...


And here's a link to another clip that shows how the TruTrac distributes torque - the Land Rover shown has the TruTracs installed in the front and rear. The "touch the brake" technique is shown at the very end...

Land Rover with TruTracs demo

GREAT PICS AND EXPLANATION. When are you going to install them?

Everet <img src="/forums/images/graemlins/patriot.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />