Failed Diff Internals - pics

Austin · 11-24-2005, 05:09 AM

I finally got around to opening up the failed diff.

http://austinm.net/titan/diffinternal

As I said on my website, in my opinion, differential failure was caused by weak spider gears (differential pinion gears) alone.

The diff carrier housing is stout, the carrier bearings are fine quality, the ring and pinion are very stout, there are tight tolerances inside the diff carrier including spider gears to side gears, spider gears to spider shaft (cross shaft), spider shaft to carrier housing, etc. The spider gears are simply the weakest link, and they gave out.

Here's a couple pics - many more on the website.

The infamous pin for the spider shaft. This is what Four Wheeler magazine said caused their diff failure - the pin sheared. While I'm too nice 'a guy to throw a BS flag, I will say that this pin is more than adequate for what it does.

New paperweights:

bestatchess · 11-24-2005, 05:56 AM

I guess those aluminum gears aren't working out.

**HudsonValleyTitan** · 11-24-2005, 06:36 AM

Quote:

Originally Posted by Austin

I finally got around to opening up the failed diff.

http://austinm.net/titan/diffinternal

As I said on my website, in my opinion, differential failure was caused by weak spider gears (differential pinion gears) alone.

The diff carrier housing is stout, the carrier bearings are fine quality, the ring and pinion are very stout, there are tight tolerances inside the diff carrier including spider gears to side gears, spider gears to spider shaft (cross shaft), spider shaft to carrier housing, etc. The spider gears are simply the weakest link, and they gave out.

Here's a couple pics - many more on the website.

The infamous pin for the spider shaft. This is what Four Wheeler magazine said caused their diff failure - the pin sheared. While I'm too nice 'a guy to throw a BS flag, I will say that this pin is more than adequate for what it does.

New paperweights:

What's wrong with those gears? Looks like the front row at a Willie Nelson concert!

bestatchess · 11-24-2005, 06:52 AM

I looked at your pics, nice write-up. Weird that they don't use a bearing for the solenoid coil. Auburn has a somewhat similar arrangement in their ECTD and guess what, they have a ball bearing for the solenoid coil. Duh.

Yomama · 11-24-2005, 07:42 AM

Austin,

Awesome write up and documentation with pics. So yours failed, did Nissan replace yours, or since you have made some modifications, did you replace it yourself? How did you get to keep your failed diff?
Mine gets replaced Monday.

*flyguy* · 11-24-2005, 07:47 AM

Any chance you can get this documentation off to Nissan somehow?

Are you replacing with a new diff from Nissan or an aftermarket?

**loufish** · 11-24-2005, 08:04 AM

Ecellent pics & text!
What are your future plans with the diff? Tru-Trac?

PrerunnerGreg · 11-24-2005, 08:23 AM

Yet again, a great photo-essay from Austin. Ive seen alot of broken gears, but never "flatend" teeth like that. Usually the teeth just break off, not really deform like that, could this be a heat-treat issue and the gears are too soft and literally just fold over and then its curtains from there?

**HudsonValleyTitan** · 11-24-2005, 08:30 AM

Quote:

Originally Posted by PrerunnerGreg

Yet again, a great photo-essay from Austin. Ive seen alot of broken gears, but never "flatend" teeth like that. Usually the teeth just break off, not really deform like that, could this be a heat-treat issue and the gears are too soft and literally just fold over and then its curtains from there?

Good call. Looks to me like the rear end wasn't properly hardened by proper heat up, cool off break-in. Like I mentioned in another thread, not something the electronics could have foreseen.

BTW, if these seem to be the "weakest link", can't they be changed out for harder gears?

Herbpov · 11-24-2005, 08:31 AM

Looks like everyone is going to have this problem sometime in the future.

**HudsonValleyTitan** · 11-24-2005, 09:08 AM

Quote:

Originally Posted by Herbpov

Looks like everyone is going to have this problem sometime in the future.

Nah. Most don't have this problem, and there are folks with a LOT of miles on their trucks.

*flyguy* · 11-24-2005, 09:11 AM

Quote:

Originally Posted by HudsonValleyTitan

Good call. Looks to me like the rear end wasn't properly hardened by proper heat up, cool off break-in. Like I mentioned in another thread, not something the electronics could have foreseen.

BTW, if these seem to be the "weakest link", can't they be changed out for harder gears?

For whatever it's worth. My dealer had told me that Nissan does not do any sort of break in procedures with the rear diffs before assembling them on the truck. They stated that is why the manual has a strict break in procedure. No towing for the first 500 miles and no speeds over 50 mph when towing for the next 500 miles.

37L1 · 11-24-2005, 09:12 AM

Any theories as to why the vast majority of the failures are 4X4's, with the BT gearing, if it's the spiders that are the weak link?

baseballfanz · 11-24-2005, 09:21 AM

Need to floss more.

For those wondering, Austin had the rear end replaced already through warranty and the service manager say he could keep his old rear end.(that didn't come out right)

**HudsonValleyTitan** · 11-24-2005, 10:43 AM

Quote:

Originally Posted by flyguy

For whatever it's worth. My dealer had told me that Nissan does not do any sort of break in procedures with the rear diffs before assembling them on the truck. They stated that is why the manual has a strict break in procedure. No towing for the first 500 miles and no speeds over 50 mph when towing for the next 500 miles.

There's also more to it. Don't forget the section explaining just how to properly break in the rear end when you DO start towing....very important! You need to stop every so often and let the rear end COMPLETELY cool before continuing on. This apparently hardens the gears. The owners manual explains this in detail. However, I think the gears should be prehardened before installation because it's a given that some folks don't read their owners manual!