Did the rear diff oil change in my 2005 Jimmy and found a piece of cast metal along with the usual small filings. The piece is curved and machined on both sides (about an inch long). I looked for more but that was it. Anyone know what it is?

 

How thick is it?

 

A little bit less than 1/4 inch thick.

Also noticed a bit of axle moan at start ups in cold weather last winter. Wonder if it's related? This looks like a piece some type of keeper ring in the axle housing but having never got past the cover plate, not sure. Also thought it might be from the axle housing but since it's machined on both sides, this doesn't make sense. Have also heard a few stories of pieces being left behind from the factory and have seen evidence of this. Found a power door lock stuck in the trunk of one car and a friend found a 5/8" socket in a blind panel in his truck after it wore a hole through the bottom. One never knows what really happens on the assembly line.

 

It's been awhile since I have had one of these apart that far... I can't visualize where that might have come from... It definitely isn't good and if there are other concerns, I would recommend you get it opened up and find the source.

 

it looks like it might be part of the c-clip the holds the axle shaft in. Im not positive though. I didnt really pay much attention to mine when i replace the axle seals

 

I thought that at first too, but the c-clips are stamped steel and only around 1/8" thick. This being near 1/4" thick and cast makes it either part of a bearing race, the diff center section, or the axle case itself.

 

Hi,

I just had my rear diff apart about 2 weeks ago to replace the front pinion bearing.

The factory shims are surface ground cast iron rings. If the radius/diameter is similar to the bearing cups for the diff carrier, that might be it.

I just noticed your photo attachment.....that looks very much like a segment of one of the shim rings. I recall that it was sharp cornered on one side and a casted radius on the opposite. Check adjacent to the bearing caps to see if there is an arc shaped segment missing.

-Jeffr

 

Thanks for all the info folks. I'm leaning towards the factory shims at this point, I think Jeffr might have nailed it. Will have to rip it apart to check. What damage will I do driving it this way? It's probably been this way for at least the last 10,000 miles so what has been wearing during this time? There has been no axle fluid leakage... so far.

 

Just had mine apart... Hard to tell how big it is but if it's almost 1/4" thick it sure sounds like the Shim between the Carrier and the Housing. That's about the only thing in therer that is that thick. Why the heck that big piece would break is beyond me.

 

The shims are ground to thickness as required during set up at the factory. They are installed prior to installation of the axles and would normally be captured (like a washer) by the axle going through the shim's hole. Additionally the overall shape of the housing and the bearing caps may also help to retain them, but I can't recall exactly how far the caps overlap the shims.

They are placed at the left and right hand sides of the differential carrier assembly, between the bearing races (cups) and the housing inner side faces. Each shim will most likely be a different thickness (i.e. left vs. right).

Normally during a re-build, the shims aren't re-used because they can break easily. But the thickness that you have (measured with a micrometer) should still be valid for the setup of your ring gear/pinion pre-loads.

You might be able to inspect adjacent to the bearing caps to see if a section of the shim has broken out. But the remainder is likely still stuck in place and acting as a shim for the bearing race, although not very effectively as the race will be partially unsupported. This will potentially cause premature wearing on the race and over time the remaining shim section(s) will work their way out, most likely for a catastrophic failure.

If this hasn't gone for too long, a quick repair would be to remove the axle(s) and replace the shim. You should be able to obtain replacement shims to match the same thickness that you had specifically on each side.

I suppose it's also possible that the shim is a broken remnant from the factory and isn't even missing from your assembly. Inspect very closely before removing the bearing caps....

-Jeffr