Bad Diff, what to do guys?
 

So guys, I have been having a thunk when putting in reverse for a long time (about 18 months) in my 2001 Jimmy 4x4 165k miles. I figured it might be rear diff, but also thought maybe the U-joints on the drive shaft. So I drove it.

Well one night it started making a metallic tinking noise around corners, so I parked it immediately and took off the diff cover plate last night. Metallic fluid started spilling out. The videos below show all. The diff ring gear and bearings jump around in there like a jumping bean.

So what do I do? Replace the gears and seals (I can do anything on a car, but I'm in med school, time it limited by hospital rotations), grab a junkyard axle that looks straight? Have it rebuilt?

In addition, I have a $350 worth of front end suspension parts short of the struts/springs that's in my garage that I need to put in, as the front was getting a little loose. It's a TON of work. Plus, the front diff seems loose as the drive shaft turns quite a bit at the front diff before hitting the front gears.

That said, tell me what you guys would do given all the work it needs done.

go with junkyard axles, now is a good time to upgrade to ZR2 diffs and 3.73's

That's kind of what I figured...

Regarding the ZR2 diffs, I've heard about them here and there while reading up, but am not sure what models they are typically in or what the main advantages are. Is it LSD?

In terms of the 3.73 gears, I am actually more interested in gas mileage at this point in my life. That said, can I upgrade differential to a ZR2 without the 3.73? Or is that the standard gear ratio they come in?

Finally, if I do get a ZR2, are there any other parts I need to upgrade in a 2001 GMC Jimmy 4x4?

Sorry, I know I'm asking to be spoon fed a bit here, just limited on time to research all this stuff. I'll trade for spoon-feeding you guys any info on the Datsun Z series or F-body Z28. :P Know all about them.

ZR2's only came with 3.73's, the main advantages were the gears and the rear end is stronger than most non-ZR2's (8.6" vs 7.5" ring gear). It is also wider so it eliminates the need for spacers to make the front and back track widths the same. They also have the G80 locker but it looks like you have one already anyway, so not an upgrade for you there.


You could also try and find a rear end from a 5 speed truck, some of those came with the larger rear end but don't have the extra width and most likely had the more common 3.42 gears.


Of course if you don't care about any of that then just get a straight replacement for what you have.

Thanks Jamaroon, I appreciate it. I guess I will have a decision to make regarding mpg vs heavier duty.

As a final question, if I get a zr2 axle complete with everything, brakes, etc, is there anything else:

1. I absolutely need for the swap, like different u bolts for springs, rims, etc.


Or

2. Anything you would recommend doing at the same time (bushings, spring changes, etc)

you should always count on new u-bolts, and probably the bolt/bushing for the spring to shackle. The rest would be at your discretion.

I am not certain but arent the spring pads wider(further apart) than 2wd or 4x4 axles. Also can anyone give aprox price of this piece?

Did you reply to the right thread? Your comment just doesn't seem to go with the rest of the thread is why I ask..


Anyway,


No, center to center of spring mounts will be the same. But 2wd axles are narrower than 4wd axles so they won't work anyway.


Price of what? A complete used rear diff? $150-$250 around here I think.

Jamaroon, you have been more than helpful.

As far as swapping. Looks like from Google that any 4wd axle from 1994 - 2004 s10, Sonoma, jimmy, or blazer will swap right over, is this correct?

But to clarify, if I do go with a zr2 axle, it will raise the rear 3 inches (so the suv will be stanced front down), and the rear tires will stick out 2 inches further on each side?

Yes any 4wd will swap over, but some have drum brakes and some have disc brakes. Easiest is to get what you have for that. Also, if you're not doing both front and rear at the same time, make sure you get the correct ratio for your truck.


The ZR2 axle will not get you any lift in the rear, the lift is done with the frame on the ZR2's. It will make it 2" wider per side.