8.75 diff - metal in oil (pictures). Is it ruined?

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No it can be refurbished. Just need to insure the cones do not touch bottom. The sides are suppose to look like that.
 
Okay thanks very much.

So I need to find a machine shot and some shims.

Still not sure where the metal debris is coming from though
 
This is what a welded spider would have looked like.

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That pinion bearing looks to have got very hot, only on 1/3 of its side, only on the face shown there in the photo...
it spins free but there is a 'lot' of up and down movement, perhaps you can comment on the video:

View My Video
 
no obvious wear or 'oh my god' areas of scratch marks etc, only the bearing which is really odd.
there were quite a bit of very fine metal bit in the oil, normal to what you might expect as it was a new CWP, some sharp edges around the area of the pinion housing but nothing else.
 
Did the guy that built the rear use heat on that bearing to make it easier to install? With those heat marks only on part of that bearing, I'm thinking that is what has occurred. That bearing if it got hot in operation wouldn't show heat in one spot only like that. The roller bearing retainer doesn't matter if it is loose like that, it only does one job, to retain the rollers till the bearing is installed. I still don't have or see a reason for all the metal in the oil?
 
better video



No I was told, the bearings were pushed on cold. so that heat has come from use...
 
oh yeah and this bit, the sleeves over the pinion is not a total cyliner, there is a slight buldge seen just about in the profile against the light:

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Hard to tell if that is a crush sleeve eliminator or the way your describing it with a bulge, is a crush sleeve.
 
That bearing is a thrust bearing, when you tighten it up, it seats. The cage does jack once its torqued down. Perhaps just a cone haircut and cleanup is all that is needed.. With that much metal I would think the area would really jump out at you.
 
Thanks, its just very slight and I noticed it. I wondered if it was not quite true when it was torqued down, might have put a bit of extra pressure on the bearing causing the heat.

So can anyone advise what is best for me to do next.

I need to machine the cones down, then shim them to counter the amount taken off.
I need to clean the diff fully
Should I just re-asemble, or should I change the bearings and give it to someone that knows all the settings required for such a complex component?
I will add a magnet to the sump plug

Concerns:
I still can not see where all that metal has come from, any suggestions further to this?
Could an imbalanced prop shaft cause any bearing problem (I do have a slight wobble up at 60mph which feels not wheel related)

I want to do this once, do it properly (even if it is a bit on the cheap and I am not replacing the suregrip) so I have a good few more years use from it.

Thanks for all your help chaps!

Jon
 
looks like whoever put the bearing on used a torch to heat the bearing --wrong on all counts unless you were stuck in some remote place --- were the ring gear attaching bolts plated gold colour when new -- the plating will come off the heads of the bolts during use and show up as gold (brass coloured) bits in the oil.
since it is apart I would replace that blued pinion bearing and any others that show this bush fix condition -- find a reputable shop to rebuild your diff with proper pinion bearing preload and correct backlash , gear pattern etc. --- one question to ask the person who will do the rebuild is -- what do you set the pinion bearing preload at --- if they look at you like your from another planet ,,, or say we set them tight -- walk away and find someone who gives you the correct answer.
majority of car/light truck differentials are set to 8-15 in/lbs. with used bearings ,,, 20-25 in/lbs. with new bearings
 
If you have an experienced Diff assembler available I would probably let him put it back together. As to where all that metal came from, it's hard to say without being there and inspecting it first hand. Make sure you clean the housing out real good. And let us know how all this turns out.
 
I want to say the metal particles came from the cones and housing. The surface doesn't look that smooth anymore with some amount of deep pitting.
With no other obvious signs of wear, that's about the only place the metal could have come from.

I think I would try to polish and break some of the sharp edges/ridges of the cones and housing and reassemble again.
 
Hi guys,

Thanks again.

Bit of an update for you, I've found a really good well respected differential builder, I'm actually having a Detroit TruTrak put in, in placed of the old cone LSD.

So the axle is now out, but I found this 'machine mark' almost like somthing was catching on the casing? lots of burrs behind it also, very fresh.

Also, check the spring perches, are they meant to be level the distances between the two red dots are not equal...

Thanks

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