Noticed my truck had a weird whirring noise and around 70-80MPH it shook like crazy. I did complete oil change all around, rotated the tires, and cleaned up the underside. Anyway I was driving and It sounded like my fan was on. ( I'm pretty shure I have a bad fan clutch) I let off my gas pedal and heard a really deep whirring noise.. And then a grinding noise, I felt it in my floorboards. Looked under and the output shaft on my diff was cracked off, and it was leaking. Limped it home to check it out and indeed it broke off and a nice little crack down the whole side of the thing. I'm thinking running it in 4 wheel drive with my front and rear end gear ratios off did it, ( I replaced my rear end with a higher ratio) but I only used four wheel drive for a super short amount of time when I absolutely had to. I noticed a lot of vibrating the past few months and I was told a improperly balanced driveline will ruin transfer cases, loose mounts, and tires that are slightly out of balance.

I have a spare case and a proper front end but I don't want to waste time putting it in if it's going to crack because something is slightly off balance. Suggestion?

 

Probably a combination of using four wheel drive with mismatched gear ratios, and the typical snap ring failure on the rear output shaft. These cases are notorious for that, and give you just the problems you now have.

Swap the axle so your gear ratios match. Stick the new t-case in there, and take it for a ride. If you have a vibration, find it, and fix it. If you don't, then you are good to go.

In either event, a t-case saver is always a good plan.

 

How off is the ratio difference?

I wouldn't use 4wd again until you get them matched up.

 

4WD and different gear ratios are a very bad thing, even for a short amount of time.

 

I'm thankful my dad bought a donor truck, I have a transfer case found.. Still stumped on what caused it. I'm thinking maybe the snap ring issue or just running it the way I did, or the fact the frame has 166,690 miles..

Hoping this fixes the sounds my truck makes, the whirring noises and the yhowling it makes at 70MPH.. Im hoping it is a combination of fan clutch and a transfer case low on oil.

If it's the transmission Going out too might be looking for a different truck.. But it doesn't skip gears or slip.. Yet. :icon_deadhorse

 

Snap ring failure will cause a crack?

 

Snap ring failure allows parts to walk around inside the t-case, this in turn tends to erode away various parts. Eventually, the whole thing fails. Grenaded t-case is the usual result.

 

Different gear ratios really won't hurt anything provided 4wd is only used in rather slippery conditions. I'm going with snap ring failure.

 

My friends dad isn't very bright...he's been using 4:10s in front with 3:55s in the rear for about 3 years now on his 1994 Ram, and he does go across the occasional dry pavement. I'm not quite sure how he hasn't grenaded that thing yet, especially when on my 97 Ram I had 255 tires on the rear & 275's on the front in my truck up until 3 weeks ago and even with that small mismatch in tire size it made my truck moan & unstable. Now with all 4 tires being the same size, its so baby smooth that I can't even tell if I'm in 4wd until I take off from a dead stop on slippery surfaces like a raped ape, the transfer case is ultra quiet.

 

Got a used replacement T-Case going in sometime this week, last we checked it was good.. I'm pretty shure a snap ring failure and running it mismatched did it in.