Stock front 4 pinion diff, how strong -> video (1 Viewer)

[Skidoo]

I broke my front diff (2000 LC) at Cruise Moab on Gold Bar Rim trail. Many folks wonder how strong the 4 pinion diff is, well I have a video of what it takes to break it. Was thinking with my driving style it would last me a long time. Well I got a little too aggressive and was not paying close attention to what the vehicle was telling me. Pretty sure if I was driving and paying attention I would have gotten up this with no drama.
From the video it survives a number of bounces and a lot of stress before failing.
What failed was the ring gear, 7 teeth broken off. The spider gears are in great shape, have no play.
To get the rig out took the drive flanges off and taped plastic over opening to keep dirt out of wheel bearings. And removed front driveshaft. With center locker on drove it out in 2 wheel drive. The bolts holding driveshaft have loctite, and space is tight between u-joints so need a strong socket that will fit in there.
If you are driving where front end will slip and grab either from bouncing or conditions like patchy ice, make sure you have the tools to isolate front diff. Of course best to drive smarter when in these conditions, and avoid the drama.
Bottom line is I feel the 4 pinion front diff is pretty strong as I had a lot of tough off road miles on it.
LC has 166,000 miles on it, 45K of it mine. All my miles have been on 295/75R16, my first set Nittos, this second set BFG AT KO, so pretty good size tires for stock front diff.

Safari Ltd, Grand Junction did a great job installing Nitro Gears, an Airlocker and solid preload spacer. If you need a repair in Moab area they are the first ones I would call.
Thanks to Kurt Williams for getting me connected to parts and service people to make it happen quickly.
Thanks to Micah and Thomas for staying behind to make sure I made it out in 2wd.

Video


[Edit - Since there seems to be some questions about isolating front diff so adding this]

To remove drive flanges, don't have to take tire off. Pop hub cap, clean area well, (see 2nd photo below) then remove little axle cap, remove clip ring. Loosen 6 nuts and back them off so heads are flush with end of stud. Hit ends of studs with hammer on brass drift, go around all 6 a few times and cone washers will come loose. Once all cones washer are loose remove nuts and cones. Remove the drive flange. Keep left and right part in marked separate bags, the clip rings come in different thicknesses and are matched to flange and axle. Cover exposed area to keep dirt out. Remove driveshaft between t-case and front diff, center locker on, you are good to go.

Photo of Ring gear

 

[paflytyer]

Sorry to hear it Skidoo........ the "Go, Go, Go, Go" isn't always the best advice from a spotter.

 

[OregonLC]

Great $4000 video though....

But hey, great opportunity to lock and re-gear! At least you were with a bunch of good folks who could help you recover.

 

[txslg]

Sorry to hear the break down.
Hope this is not an expensive fix

 

[Trunk Monkey]

That's disheartening to see, those hops aren't that big and about what I'd expect to bump up a ledge like that. Wonder how much sooner a 2 pinion would have gone.

 

[OregonLC]

That's disheartening to see, those hops aren't that big and about what I'd expect to bump up a ledge like that. Wonder how much sooner a 2 pinion would have gone.

But those hops could be the straw on the proverbial camel's back. It's not always the last event that was the true cause.

 

[TrekboxX]

Wow. Sorry to see/hear. That sure is discouraging. Only took a couple of hops before it gave. Not too impressive, imo. I would have thought it would survive that no sweat. Guess I'll have to add a locker as well...

Nice rig BTW!

 

[sonk76]

Video http://youtu.be/v1QqHZ7Sme0

This is almost exactly how I broke my 4-pinion front diff (climbing obstacle, front wheel off-loading, then landing...) , and also the failure point was exactly the same (i.e., it was the ring gear teeth that gave up rather than the pinion gear(s))

I've been happy with the Nitro 4.88's and ARB front diff since then... that said, given that it was the teeth on the ring gear that failed (not the diff proper per se), it makes me wonder just how much more strength my current setup has... perhaps in practice it's the ability to lock the front, which prevents this kind of shock load that is the real reliability improvement (I don't intend to test it to find out...)

 

[paflytyer]

Wow. Sorry to see/hear. That sure is discouraging. Only took a couple of hops before it gave. Not too impressive, imo. I would have thought it would survive that no sweat. Guess I'll have to add a locker as well...

Nice rig BTW!

I think you guys are not looking closely. That slickrock is sticky stuff. The front is slamming down and completely stopping that wheel from rotating. That's a huge amount of force.

 

[bluecruiser]

Those were a couple of substantial hops...I've been in the broken diff club for about 6 years...mine was two pinion but broken in a very similar type situation...
FYI, I went up that same spot in CM this year after running Golden Spike, front locker on and sipping a caramel macchiato from a porcelain cup found in the Titanic wreckage....

 

[e9999]

sorry to read that.

want to put the vid in the 100 vid thread? could save somebody's diff...

 

[2003lx470]

Saw the video and painful to hear that noice!!!!!!

 

[paflytyer]

FYI, I went up that same spot in CM this year after running Golden Spike, front locker on and sipping a caramel macchiato from a porcelain cup found in the Titanic wreckage....

With Missy Elliot's Supa Dupa Fly on blast, windows down, hat to the side......

 

[AimCOtaco]

The picture looks like it was just the ring and pinion? I would say the 4 pinion diff held up but the ring and pinion did not no?

Many times stock R&P are used with an ARB. The exception (making it the diffs fault) would be if the diff flexed leading to the R&P failure.

There is no such thing as unbreakable steel. At least we have enough power to break stuff!

 

[Skidoo]

sorry to read that.

want to put the vid in the 100 vid thread? could save somebody's diff...

Thanks! Done with link back to this thread also.

 

[KlausVanWinkle]

Wow. 5 bounces and the last 2 were huge. I'm not sure what to take away from this. I'd have thought ATRAC could have helped you walk it up. But then again, video and pictures are always deceiving.

Good to hear you made the most of it and got to regear and lock it.

 

[SanDiegoCruiser]

Wow, I've got the 2 pinion and have bounced a little like that in the past. It's just a matter of time before mine explodes.. I'm sure.

 

[1loudLX]

This is almost exactly how I broke my 4-pinion front diff (climbing obstacle, front wheel off-loading, then landing...) , and also the failure point was exactly the same (i.e., it was the ring gear teeth that gave up rather than the pinion gear(s)

Pretty much. We had to go do that one last run, your diff and my CV.


Hopping like that I could DEFINITELY see how that diff blew. Like paflytyer said, that spot is really sticky. Sucks to see this happen to ya skidoo. What PSI were you at with your tires, they looked pretty stiff in that second view.

 

[Skidoo]

Pretty much. We had to go do that one last run, your diff and my CV.


Hopping like that I could DEFINITELY see how that diff blew. Like paflytyer said, that spot is really sticky. Sucks to see this happen to ya skidoo. What PSI were you at with your tires, they looked pretty stiff in that second view.

20psi and tires are brand new, bought them before trip out.

 

[jonharis]

Sucks that it happened when I did. You were in good hands at Safari-Ltd. though. Keith is a master at ARB/Gear setup and you should be good to go for many years to come.