Failed Diff, Hmmm...I think I know what happened...
 

Eaton tandem real axle-differential - front differential of the tandem set has failed after 78,000 miles. The pics are of the pinion gear and the ring gear. Both gears have suffered catastrophic failures. Reviewing the pictures shows that both gears appear to have suffered stress fractures leading to failure.

What do you guys think caused it?

http://forums.pelicanparts.com/uploa...1289603146.jpg
http://forums.pelicanparts.com/uploa...1289603169.jpg

sorry for the lack of quality of the pics - customer sent them in. I was hoping for the actual parts. I hope to get them in over the next week or so.

We went through a period where we had failures that look exactly like that in our 935 clone with a G50 box. We set the r&p according to Porsche procedure, and broke three sets in a row. Now those were very short track outings..

On the next build we said eff the Porsche set up, and got out the Prussian Blue, and set the r&p by eye, and have not looked back..not a failure in...going on five years..

Looks like a set up failure, was that box rebuilt recently? Or to much power beiing passed through the box...

Dont' think its a failure due to lube..

Also doesn't look like heat was a factor.. no bluing etc..

How much experience does the driver have?

I would be wondering if some sort of shock load was applied to those gears, maybe driver starting out too hard, and lurching the truck, or maybe stuck and and trying to rock it out. Or set up with too much backlash.

Hard to tell from the pictures but i'll guess driver abuse.
40k lb or 44k lb rears? Either way it takes a lot of torque to twist the pinion teeth off.
I think the damage to the ring gear is from the pinion coming apart.

they used snow tires?

Overloaded axle + shock.

I'm guessing bad gear oil... ;)

looks like some fast food got caught in there and "broke the metal"

What happens over time if you haul your car on a trailer and strap it down through the wheels instead of the body frame..

The only time I ever saw anything like that the preload on the pinion bearings had loosened way up, and there was a rodeo clown involved.

Too many bolt-on upgrades without any attention to the drive train?

Can you give us the make and model of vehicle? That would help understand if it was something like I mentioned above or an overloaded bread truck.

Close but not quite.. I think it may even be an urban legend..

That is if you strap your car down by the wheels, and leave the transmission in gear... I have heard about these failures, but have never seen one in person..

BTW I strap my car down by the wheels.. lets the suspension work..

Someone (our driver) did something like this trying to drive with the parking brake set. Ripped the pinion right out of the diff. I thought the drive shaft would have failed first.

I didn't know you were supposed to put the Cool Collar in there...

One too many burnouts....

JR

hahahah

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Gear oil with the new tungsten shot additive ?

Multiple red line clutch drops with no tires on?

Do tell.