I did it about a week ago. 55K on my truck and I put it into 4x4 because of snow. After about 4 miles the left U joint at the hub broke and the gears were all messed up in the front diff. It was the first time i used 4x4 in a long time because I don't go off-roading.

I changed the diff fluid and gasket at 48K miles with valvoline synthetic (80W) and some lucas stabilizer.

I am having the work done with my extended warranty, so it is not really a big deal. But I am wondering if front diffs just grenade themselves when you are NOT crawling rocks. I had noticed the 4x4 being kinda clunky for a while, but I hardly used 4x4, so I never thought much of it.

 

Is it possible that the gears binded up and broke when your u joint failed? sound like that what could have done it...
Lucas stabilizer huh? I thought you dont believe in additives

 

Ah, that is interesting, if the U-loint popped, then still being engaged in 4x4 would pose a problem. THere was a weird thing:
1. THe u Joint was still intact, it was just shifted out of position. It was running ragged then I had put on the brakes and heard a POP. The front was smooth again, like the Ujoint went back into place, then it came off again.

I use lucas, ust not the stuff that either thins your oil (engine flush) or things that bake onto your engine (restore). But I do like lucas in the oil.

I added the lucas to the diff just to make it thicker. I had the gallon jug of lucas and they only had enough 80W at the store for me to do both diffs, and not enough 140W. So I went with 80W and added about a quart of lucas to each diff. The bottle says that you can use 100% lucas for diffs. But it was a tad cold when I did that change and the lucas pours like molasses in the cold.

 

I used 100% lucas in my rear diff..(until I had the LSD rebuild). If the u joint shifted it still could have momentarily bound up the gears right?

 

I vote for ujoint shifting. Unless you forgot to tell us that you had the front end in a water hole and drove it that way for a while. Or maybe factory install was bad. But most likely ujoint. Makes me feel better for changing mine out as soon as they have even a little movement to them.

 

the ring, pinion, and spider gears are all very solid and i'd be surprised if any of that actually broke. the yokes on the end of the shafts are the weak point, and the shaft itself is the next weakest.

those gears usually last a lifetime, whether you use 4wd or not.
got any pics?

 

No pics. The repair place said that the front end was pretty chewed up and there was damage visible with the cover off. Maybe it was not the gears, but the axle splines. DO you mean the yokes bear the hub? Or are their yokes internal when you take the diff cover off? The warranty place sent an inspector to check out the damage, and he blessed off on the repair, so i have had no worries. I don't blame them, because I had my LSD replaced in the rear in june. Reason was because the backlash was not correct, and that is a factory set thing!!! My truck was made in the Saltillo plant in Mexico. Not Detroit!

Since I have bought the truck in 2008 at 42K, I have had:
1. New Power steering pump (Chrysler warranty)
2. New Transfer case (Chrysler warranty)
3. New Posi (Route 66 warranty)
4. Front end stuff (Don't have the invoice. I have been more concerned with getting the truck back and have been busy with grad school to go to the shop). (Route 66 warranty)

I apologize for not taking pics of the ujoint after this went. When it did go out, it seemed like I heard noises from two places. From the hub area (Ujoint) and another spot like the pumpkin.

 

My truck is also a mexican dodge.... and I also have a new transfer case and and rebuilt lsd /pinion bearings and all kinds of other replaced goodies....I dont think there many original parts left at all actually...
I got a kick out of the fact that the UAW will let me enter the gm plant to do work in my mexican dodge but my Toyota made in Illinios cant get past the gate... even though they were sold as chevy's too and cavaliers are sold as toyotas in japan...UAW wasnt getting paid on the Toyotas I guess... never mind keeping the jobs here in the states...

 

My truck is also a mexican dodge.... and I also have a new transfer case and and rebuilt lsd /pinion bearings and all kinds of other replaced goodies....I dont think there many original parts left at all actually...
I got a kick out of the fact that the UAW will let me enter the gm plant to do work in my mexican dodge but my Toyota made in Illinios cant get past the gate... even though they were sold as chevy's too and cavaliers are sold as toyotas in japan...UAW wasnt getting paid on the Toyotas I guess... never mind keeping the jobs here in the states...I dont know whats worse at this point mexico or detriot?... Have you seen how poor that City is right now? they actually have abandoned skyscrapers along with half the houses being empty...check out the videos on youtube..

 

I hear ya!!! Buying american is not necessarily buying american nowadays (or vice versa). It is just a matter of WHO gets the cash in the end. Toyota gets the profit from american workers, and Chrysler gets the profit from Canadian and Mexican workers. However, it is weird because DIAMLER CHRYSLER used to own dodge until 2007. In 2007, Cerberus capital management, based in NY) bought chrysler from Diamler. so NOW it is an "American" owned company. So really, you and I own "german" trucks. Don;t tell them that the next time the UAW asks about your truck!

Weird how we both have the same problems for mexican dodges. I had a completely new posi put in because it was actually cheaper for the labor to replace the major part than to replace the bad parts.