Rear Diff noise w/vid (1 Viewer)

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Joined
Feb 6, 2006
Threads
25
Messages
133
Location
Fort Worth, TEXAS
96-97 fzj80 open rear diff. (not on an 80 though)
Before I ever drove it,
Had diff rebuilt by shop 1, they screwed up the crush sleeve and basically trashed the gears. became noisey really fast. more of a whine then became a rattle. gears were worn to a knife edge.
approx 250 miles later
had diff rebuilt by shop 2 with used set of gears, patterned good, and used a solid spacer properly done. reused bearings as they said they were not damaged. noise was the same after.
2500ish miles on it so far
no noticeable wear on the shaft splines when I pulled it for shop2.

dirving it does it on no load coast only, not decel or accel. can be heard at speed all the way down to nearly stopped.

noise did not change when either wheel was stopped and the other let to spin through the spiders.
using a stethoscope, noise is heard as a ticking rattle at the snout, but much more pronounced at the rear cover. does not sound like the typical gear whine. more of a grinding or bearing(?) that is running dry.

loudness washed the mike out...
60ish on the hwy: https://www.youtube.com/watch?v=7XeXO7bmnzs&feature=youtube_gdata_player
35ish on stands: https://www.youtube.com/watch?v=jGknZpgCY20&feature=youtube_gdata_player

axle was not in a rollover, I did weld on the housing, but not alot and did not let it get to hot. had 60k on it when I got it.

help? i am limited as far as when I can work on it and pull it apart, so I need to gather as many ideas as I can before I get into it.

thanks,
Kyle
 
yeah I'm thinking a spun bearing... going to pull it out hopefully this weekend...
 
Pull the diff cover and drain plug. Any loose metal? To be honest, that sounds more like ring gear and pinion than a bearing. In the last video, were the rear tires off the ground?

yes,

no dif cover on a 80 rear axle. (or front for that matter)
 
If the entire ring gear was worn down to a sharp edge on each tooth, that is a huge amount of metal floating around inside. I don't see how the entire insides of a diff could not have suffered tremendous wear. I think it is time to start over and get some complete used axles, or at the least complete used pumpkins. Why did you have the diffs rebuilt in the first place?
 
Watching this thread, mine has the same noise. Showed up a while ago. Still there after I had the rear pinion seal and bearings replaced. Really loud at 60 and above, but can be heard at low speeds too.
 
If the entire ring gear was worn down to a sharp edge on each tooth, that is a huge amount of metal floating around inside. I don't see how the entire insides of a diff could not have suffered tremendous wear. I think it is time to start over and get some complete used axles, or at the least complete used pumpkins. Why did you have the diffs rebuilt in the first place?

new (different) pinion flange. Crush spacer the first time.

would have to swap the pumpkins. the housing is welded upon quite heavily. Will snap some pics when I can pull it apart. Hopefully this week one evening.
 
pulled it apart. Oil was Mobil 1 75/90 LS Synthetic.

A big mound of black "metallic" goo stuck to the magnet.

Drained (most of) the fluid through a paper towel and quite a bit more of the goo was in the oil, as well as in the housing.

No abnormal wear on the shaft splines.

No abnormal wear on the gear faces (unlike the first time).

No roughness in the bearings that I can feel.

Backlash feels like a long tick, but not too much from my experience.

No visible damage to the gears or the housing.
 
Got photos of the goo or the gears??
 
Got photos of the goo or the gears??

will get them later tonight.

the amount of goo was not excessive, it was there though. I assume it is mainly from the gears re-seating.
 
The most reliable method for finding this problem is a set of chasis ears. Find a mechanic near by who has chasis ears and will work with you on this problem.

Start by putting one ear on the front diff and the other two ears at the ends of the front axle and drive the vehicle. If the sound isn't there, do the same on the rear axle. Then put one ear on the center of the transfer case and one on the front and rear nose of the transfer case. If you still haven't found the problem, remove the rear drive shaft (lock the center diff). Then do the same with the front drive shaft.

At that point, you will have examined your entire drive train with the exception of the transmission and engine. I am guessing it is neither of those items and is located somewhere in one of the items mentioned above. This approach will save you time and money and help you avoid replacing / rebuilding items that are not a problem.
 

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