Certainly the newer 4 spider rears will be better, but the factory locking versions still have a thin cut side gear. And the front is just hopeless all years.

I have an appointment for tuesday to take my 06 OR in and have the rear differential checked. For the last 3 weeks I have had a vibration from 25 to 35 mph. This friday I had my tires rotated and rebalanced in case that was the problem. After driving it they put it in the air and put it in gear. There was a grinding sound coming from the rear differential when they held one of the rear wheels. I have not really had my X off road. I have had it on dirt roads in 4 wheel drive 3 times. I have been towing a travel trailer with a dry weight of 2840 a couple of time for a total of 500 miles. This does not sound good.

Keep us updated.....

Is it true you really have your X parked until the diff situation is solved? I plan on going to the dealer to find out if the diffs are covered past the 36k warranty under the 60k powertrain warranty. Do you happen to know? Thanks

Stay off the skinny pedal! Don't spin your tires like an idiot when they come loose. Don't hang tires that are a couple of inches bigger and twenty or more pounds heavier. Don't drive around for ten - twenty miles with the rear differential locked.

I parked it until now. Next week it goes to a mechanic and to try and see if the Titan Trac Loc will replace the stock POS locker, while the lawsuit begins.

But yes, the differential should be covered under the 60K power train.

As far as staying off the skinny pedal? I did. As far as bigger tires, 1"? Talk about delicate.

Just a side note, the complaint Nissan had about a larger tire, was that it with the lift raised the vehicle, which created leverage against the differential They gave that one up before the extra torque from the lifted pinon angle

In the case of my Xterra, It still has the stock tires. At 12,000 miles I cannot justify replacing them. When the time comes, though, I planned on replacing them with the BFG 32" tires. I have also pretty much kept off the gas since I hate what that does to the gas mileage.

Please let us know about the Titan Trac Loc exchange. Will it still be a differential lock or just a locking differential?? I don't mind spending money to replace the diffs since there is no other vehicle that I want. Thanks Also, a great site about 4x4 and diffs is http://www.4x4abc.com/ML320/ml320_traction_etc.html

It will be just a LSD.

a larger tire size def would create more "leverage" against the diff.

Against the SPIDER GEARS though?

whatever tangential force is applied to the cirsumference of the tire will be transferred as torque along the shaft and into the diff, gears transfer that force along on the gear train. whatever the weakest point in the train is what ends up fatiguing or blowing first. the larger the tire, the larger the moment that is initially created causing more force to be sent down the line to further components.

Of course MANY people have broken with stock tires. Would be interesting to know how much another 1" of tire really would add....Any automotive engineers out there?

I still will rehash.....A Rubicon 44 handles 35-37" tires, a stock 20 year old Montero that came with a P225 handles 35-37" tires, THEN you start with an occasional axle break. So whatever the forces on the Nissan D44, clearly it was under engineered.

I agree, there is no way you can point to 1" larger over factory as the problem. Sure it's might be a cause, but it's not the problem. I could see this argument if the stock tires were 28's and you were putting 33's on, but that's not the case. The stock tires on an OR model are 32x10.50x16 and more people are running 33x11.50x16. We are not talking about a large jump in size here.

Now, what i will say is the weight difference between the stock tires and most of the more aggressive off-road tire is quite a bit (even staying with the same size). But again, I point to the fact that with with the D35 in Jeep (which are just axles), people break axle shafts a lot sooner than they blow up diffs.

Having your diff the weakest part of the driveline is the stupidest thing I ever heard. I would not be afraid or complain one bit if I was blowing half shafts or axle shafts. That can be expected.

nissan could have made the diffs stronger, but they didn't. It sucks, but they could "prove" that larger tires caused the failure because theoretically they can. even though it prob isnt why it failed in reality. those diffs prob would have failed regardless. larger tires could cause it to fail sooner though based on the fact that it causes overall higher alternating stresses thus shortening its overall lifespan.

Mikey I understand your principle, and I have applied it to a failure on my 1990 Montero. Designed for 225 tires, and having 33s then 35s for the last 100,000 miles. Both rear axles incurred a slight twist in the splines causing rear axle leaks. This is a well documented fatigue failure on 4x4s with large tires. Luckilly it took a long time to happen.

But fatigue failure on spider gears? And after only 6 trips off-road, 5 of which short, casual trips? And only 2 trips with a 1" larger tire?

I submit they CANNOT prove that the larger tire or lift alone could have caused the failure. AND...
They have to argue why...

1. There are thousands of failures of the exact same nature, regardless of use off-road or tire size.
2. Why they switched to a 4 spider diff sometime in 06.
3. Prove that the 2 spider gears, small cross pin and thin locker gear are not under engineered.
4. Why they promoted and helped design the lift, and display it on no less then 2 company vehicles and allow dealers to install them.
5. Why there diffs are some of the only ones ever designed with such a small factor that they cannot handle stock tires or 1" larger tires, including the brutally weak D35. And why are they 40% smaller/ weaker then prior Xterras with smaller tires, less HP and Torque and less weight? And why can everyone run 33s on those diffs without explosions?

I believe the new Rubicon axles are essentially the same thing the Nissans have. The difference - a lighter truck and less HP, but I wouldn't be surprised that as we see lifts, etc. going on the new 2007+ Rubi's, they'll be having failures too.

Add 80+ HP over the old models and put in much weaker axles. I just don't understand the thought process.

Nissan better address this. Myself, I'd love a new Frontier, but this will keep me from buying one, unless I get one with the full intent of doing a SAS and swapping out both axles.

If that's the case Andy, You definately wouldn't be buying it off a Dealer lot and having next to Zero mileage.

I'm sure you can find someone at some point that may have no warranty and a blown diff and pick it up that much cheaper. Sucks for them, good for you.

this may be a crazy question, but does anyone know if CAD files are easily obtained for the D44 spider gears? I could just throw one onto one of my company templates, spec out a better steel, and have our machine shop quote a price.

The Rubicon may have the same axles, but not the same differential carrier and weak components, that is a Nissan special. The problem is not just weak spiders. It is 2 Vs 4 needed in early models, and the shaved side gear for the locker. To fix the problem the locker would need re-designed I think.

The only side gear I can recall breaking was being used in an off-road Race truck.

I don't remember reading about any other side gear issues, just Spider gears.

Mikeyo you just call up Dana and ask them for the CAD I'm sure they'll comply.

I hope that someday, if the 4 gear setup is proven unreliable, someone will machine new spider gears to use. I know Xterraracer is working on a Spool, but that would suck on a daily driver.

Other than that save up on the Mod money for Sas and better 3rd member. Definately keep the X unmodified until then to keep the warranty intact.

I honestly don't think anyone knows that has been failing in the rear. My dealer didn't open it up and wouldn't let me. They said it had to go back to Nissan like it was.

So it could have been a side gear.

The Tech Inspector checked it out and listed cross pin and spiders, as to be expected. Mine is being towed to a shop now. Will check it out myself.

The side gear is certainly more of an unknown. But if I read Xterra Racers tone of voice from his typing...its gonna be a problem, especially with bigger tires. Remember, it really takes 35s to hang out on trails today. 32s blow the spiders...35s....

I wouldn't rule it out as problematic, but until we see some everyday use causing it issues I'll disregard it as isolated.

32's are Stock, 35's yeah would be nice, but impractible for most people and the lift required to stuff them is pricey at best. SAS would be the correct route regardless if you wanted to "hang on the trails".

Good luck at the shop and I hope you can post a couple pictures of your diff.