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broke a tooth in my rear differential gear box


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I replaced my 'rear differential gear oil' a year ago.
I recently noticed my 'rear differential gear cover' was leaking.... some bolts were loose and i just snugged them up.
I popped open the 'fill plug' to top off my gear oil and noticed these two large chunks of metal. is my 'rear differential' going to grenade itself soon? the 'differential gear' was low about 125cc of 'differential gear fluid' I believe it uses about 1500cc of 'gear oil'.

I suppose I could pop off the plug every week to see if anything else starts shredding off. I am also planning on replacing my leaf springs. maybe it is time for a new rear axle as well /facepalm

I noticed most of the rear axles at pick-n-pull have the rear differential exposed. to the workers just pop the cover off to drain fluids and throw it to the side?
would unskilled engine braking contribute to the damage?
 

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ericbphoto

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Personally, I would drain the oil, remove the cover and inspect everything inside to evaluate the extent of any damage. Then decide how to proceed. You don’t really know exactly what those pieces broke off of until you get in there and look. Just topping off the oil probably left contaminants in there that are circulating around through your bearings and gear teeth. The very minimum should have been to drain, clean and refill with all new oil.

If necessary, a used axle is an easy way to repair. But you still don’t know the “new” axle unless you clean and inspect it also. It’s kind of a gamble.

A thorough cleaning, new ring and pinion set, complete diff rebuild kit and new wheel bearings and seals should make your axle good as new. But it’s more expensive if you can’t do it yourself.
 
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I live in an apartment, i have a limited tool bag and I have limited mechanical experience. im going to finish todays tasks (drive around a bit), check fill plug magnet for more debris and then do a fluid remove/replace
 

Josh B

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I've known people who worked on their autos at apartments, but made sure it all got done on Sunday.
If that's possible for you it can be done in a day.
Get your parts together, get the bearing puller from parts store loaner, the seals can be driven without the tool, just be careful with the hammer, or get the loaner seal driver.
 
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*BUMP*

My rear end started clunking last night.
-When I accelerate in gear i hear a repetitive clunk, when i coast out of gear i hear a very loud repetitive clunk.
-I checked under the vehicle and the drive shaft rocks back and fourth about 15 degrees of a rotation, and makes a loud clunk as it hits each end. I sent a video to my friend and he says driveshafts should rock back and fourth a bit, but mine is excessive. There is no forward/backward/side-to-side play
-I jacked up each side of my rear end and as i spun each tire, it seemed every two rotations i would hear the clunk and feel a bit of resistance.
-I checked my oil level and it was fine. magnet was mostly clean aside from one small cube of metal about half the size of the small piece of metal in the picture in the first post of this thread.
-My ujoints feel snug, but i read that i need to disconnect the driveshaft to be able to feel if they are loose.

I believe my next step would be to either remove driveshaft and feel ujoints for play or drain and inspect rear differential gear box.
Suggestions?

Additional info:
This happened on the highway immediately after i quickly decelerated when someone pulled in front of me going about 55 and then slowed down to 40ish. Odd. iirc i remained in gear and then also applied my brakes.
Also i have gotten into the habit of coasting in gear and decelerating in gear and i wonder if i have formed some bad shifting habits that may have lead to premature wear of my drive train
 
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ericbphoto

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When you manually rotate the drive shaft and see that 60 degrees of movement, is the transmission in neutral?
 

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I'm not sure about the clunk, but I've always checked u-joints in vehicle. Block a wheel, trans in neutral, rotate shaft by hand while looking very closely the yokes stay in sync. If one side starts moving slightly after the first side, then its pooched.
 
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When you manually rotate the drive shaft and see that 60 degrees of movement, is the transmission in neutral?
Okay, my memory was way off with 60 degrees...
In 1st gear it barely wiggles.
In neutral, the driveshaft rotates like 10-15deg. I dont know if that is normal. My buddy watched a video of it and said it looked pretty sloppy. ill see if i can post it here.
I am going to go underneath and see if i could move the ujoints with a prybar
*edit*
I pried with the truck in gear and the u joints did not seem to budge. The only play i felt seemed to be coming from the ends of the u joints where they meet the transmission or rear differential.
 
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dvdswan

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Man, I was hoping for a picture of carnage like this...
Differential Failure Analysis | West Coast Differentials


Seriously though, setting up gears is not for a novice. I'm not saying you can't do it but you will need some special tools. Todays prices you can see a gear swap around 700 at a shop. If there are chunks in the oil the shop would probably want to replace bearings and carrier as well. Then you would be looking around 1500.

You can find an axle at a junkyard from 100-300 usually. As long as the axle isn't sitting in mud and/or covered with rust they are pretty safe to use. An axle swap can be done usually in half a day if you've got all the tools, jack stands, and jack.
 
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dvdswan, do you think opening it up would tell me if there is damage inside?
Perhaps there are more metal chunks that havent had time to catch the magnet?

Is this also an opportunity to pull a rear LSD axle from an explorer 'sport'?
I am under the impression these would be good for when i often leave the pavement.
Are there any cons to LSD for regular highway driving? heavier weight/more drag/less mpgs?

im thinking that the quiet clunking when accelerating and the loud clunking when coasting must be a clue, ya/na?
 
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dvdswan

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Pulling off the diff cover will definitely give you the view of telling if the gears or carrier are toast.

But I would verify all the above before you do this. A u-joint that is toast can make a lot of noise.

This is the view that you would see...

Screenshot 2023-12-26 135124(1).png
 

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I feel like when you pop off the cover, you will be misisng more than a piece of a tooth, luke in the picture you posted. Clicking every two rotations of the wheel sounds like you sre going to be missing 3 or 4 teeth.


And downshifting to slow down will not cause that issue. Being very low on fluid could though because that could be the face of a tooth missing, not the whole tooth.
 
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I paint marked and disconnected the driveshaft bolts from the differential and played with the u-joints with my hands and they feel smooth and fine. should i try to pry at them with crowbar?
is it now time to open up my rear differential?

*Transmission fluid leaked from my transmission when i pulled the spline side of the driveshaft out, is that normal?
**I dont drive often in the rain but i drive through dry dust often for an idea of the wear that my u-joints encounter, 315kmi
 

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I paint marked and disconnected the driveshaft bolts from the differential and played with the u-joints with my hands and they feel smooth and fine. should i try to pry at them with crowbar?
is it now time to open up my rear differential?

*Transmission fluid leaked from my transmission when i pulled the spline side of the driveshaft out, is that normal?
**I dont drive often in the rain but i drive through dry dust often for an idea of the wear that my u-joints encounter, 315kmi
Depending on how level the truck is sitting, some fluid coming out of the tail of the transmission is normal.

If the u-joints look and feel fine when manipulating them by hand, then they aren't the problem.

If you can safely do so, put the rear of the truck up and jack stands and spin the wheels by hand without the driveshaft installed. See if you feel anything. It might be time to pop the differential cover and take a look as well.
 
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sgtsandman, i jacked up the rear right wheel and spun the tire. it makes a thud/thump/(clunk) from the differential every 2-1/4 revolutions. I also felt a rough, area with a little resistance and a mild grinding noise at the same spot once every complete revolution
...
Okay, now i just raised the left side and when i spin the left wheel, there is same thud every 2-1/4 revolutions, moderate grinding noise, and massive amount of resistance in the same spot with every revolution of the wheel.
Time to pull the cover off.
 

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